Table of contents :

Nervous system (neurology) : the organ system which, along with the endocrine system, correlates the adjustments and reactions of an organism to internal and environmental conditions. It comprises the central nervous system (CNS) and peripheral nervous system (PNS): the former is composed of the encephalon and spinal cord, and the latter includes all the other neural elements

• neurobiology : 33% of 100,000 genes encoded by human genome are expressed in nervous system cells
• neuron theory : (Waldeyer, 1891), the theory that the nervous system consists of innumerable neurons in contiguity, but not in continuity
• neuron doctrine : the doctrine that the nervous system is entirely cellular, that its cells are distinctive as to morphological type and functional characteristics, and that its cells are not in protoplasmic continuity but are juxtaposed without a significant amount of intervening extracellular substance.
• avalanche theory : the theory that nervous influence increases in force as it descends along an efferent nerve
• local circuit theory : in neurophysiology, the theory that current flows from the unstimulated, positively charged areas of the cell membrane of a neuron to the stimulated, depolarized or negative portion, and that as each new area becomes depolarized or negative, it in turn acts as the sink toward which the current flows from the adjacent area, which results in progressive depolarization, or reversal charge, along the neuron from the point of stimulation; the source of the current is the flow of Na⁺ into the cell.
• core conductor theory : a theory regarding the development of electrotonic potentials and their associated currents along nerve fibers, according to which the nerve fibers are considered to be core conductors, i.e., cylinders of conducting fluid material with a sheath of high electrical resistance, surrounded by a layer of conducting medium.
• Golgi's theory : the theory that the neurons communicate by the axons of Golgi's cells and the collaterals of the axons of Deiters' cells.
• facilitation : in neurophysiology, the effect of a nerve impulse acting across a synapse, resulting in increased postsynaptic action potential of subsequent impulses in that nerve fiber or in other convergent nerve fibers.
• neurotrophic factors :
• neurotrophin family
• NGF
• BDNF
• PEDF
• NT-3
• NT-4
• cytokine family
• CNTF
• LIF
• IL-6
• cardiotrophin 1
• TGF-b family
• GDNF
• neurturin
• persephin
• FGF family
• HGF
• IGF family
• IGF-1
• IGF-2
• axon outgrowth : SEMA7A functions independently of plexin C1, interacting with the b₁-integrin receptor to modulate axon outgrowth (via the downstream signaling targets of the integrin receptors, including FAK and MAPK) and is required for proper lateral olfactory tract development in vivo.
• filovaricosis : the development of varicosities on the axon of a nerve fiber
• neuronal apoptosis
• NGF withdrawal from sympathetic neurons in vitro causes programmed cell death via the well characterized mitochondrial pathway, involving cytochrome c release and caspase 3 activation
• GDNF withdrawal causes programmed cell death via mitochondria-independent pathway
• different types of cargo vesicles containing presynaptic proteins are transported from the nerve cell body to the nerve terminal, and participate in the formation of active zones. However, the identity of the membranous cargoes and the nature of the motor–cargo interactions remain unsolved. Syntabulin attaches syntaxin-1-containing vesicles to microtubules and migrates with syntaxin within the processes of hippocampal neurons. Conventional kinesin I heavy chain binds to syntabulin and associates with syntabulin-linked syntaxin vesicles in vivo. These findings suggest that syntabulin functions as a linker molecule that attaches syntaxin-cargo vesicles to kinesin I, enabling the transport of syntaxin-1 to neuronal processes^ref.
• 2 distinct pools of synaptic vesicles appear to be involved in the spontaneous release of neurotransmitters and in neurotransmission triggered by a stimulus. Their findings raise questions about a fundamental theory of neurotransmission developed by Bernard Katz^ref. When studying the spontaneous fusion of synaptic vesicles in rat hippocampal cells, using dyes that fluoresce when inside a cell membrane^ref, the researchers found that when vesicles were allowed to fill in the absence of network activity and then subjected to stimulation, loss of dye was slow. When activity was induced, vesicle destaining showed an initial rapid phase, then slowed to the rate of spontaneously loaded vesicles. Their conclusion was that there may be 2 types of recycling vesicles. Spontaneously recycling vesicles are reluctant to release neurotransmitters during stimulation, but do so readily in the absence of activity. Activity-dependent vesicles show the reverse pattern. These findings question one of the core tenets of synaptic function and reveal significant complexity in organization of synaptic vesicles within individual synapses. This conclusion challenges the "quantal" model of neurotransmission, which assumes that active release of neurotransmitters and spontaneous release ("miniature synaptic potentials") use the same pools of vesicle. The quantal hypothesis is not invalidated, but that its assumptions must be now be tested when spontaneous neuron potentials are analyzed^ref.  The results raise the question of whether miniature synaptic potentials^ref reflect accidental release at synapses with a hair trigger for evoked release or a background form of transmission cycling within their own vesicle pool. One of the significant questions is "How do vesicles end up in this situation?" Mice engineered to lack synaptobrevin-2 showed no evidence of activity-dependent recycling
• neuronal synapse / synapsis
• chemical synapse
• neuromuscular junction (NMJ)
• electrical synapse / ephapse
• motor unit : the unit of motor activity formed by a motor nerve cell and its many innervated muscle fibers.
• subsynaptic web : a system of filaments or fine canaliculi which have been observed to penetrate at a varying distance into the postsynaptic cell
• synaptic plasticity : the ability of synapses to change as circumstances require. They may alter function, such as increasing or decreasing their sensitivity; or they may increase or decrease in actual numbers. This phenomenon is thought to be the main source of the overall plasticity of nervous system pathways.
• altering the distinct patterns of Ca²⁺ spike activity spontaneously generated by different classes of embryonic spinal neurons in vivo and in vitro changes the transmitter that neurons express without affecting the expression of markers of cell identity. Regulation seems to be homeostatic: suppression of activity leads to an increased number of neurons expressing excitatory transmitters and a decreased number of neurons expressing inhibitory transmitters; the reverse occurs when activity is enhanced^ref
• if wisdom comes with age, then brain cells are some of the wisest in the body: researchers have applied carbon-14 dating to DNA to confirm that cells in the brain live longer than most others. Carbon-14 dating looks at the ratio of radioactive carbon, which is naturally present at low levels in the atmosphere and food, to normal carbon within an organism. While a creature lives, eats and breathes, its ratio of radioactive to normal carbon will equal that of its environment. But when it dies, this ratio will fall, as the carbon-14 decays. Radioactive carbon decays slowly, such that a given amount of carbon-14 halves every 6,000 years. So detecting the subtle change in the ratio of normal to naturally occurring radioactive carbon over just a few years is incredibly hard. But it can be done if one takes advantage of the signal left by nuclear testing, which spewed high levels of carbon-14 into the air during the Cold War. By the time a halt was called to aboveground nuclear testing in 1963, levels of carbon-14 in the atmosphere had doubled beyond natural background levels. Since the halt, this has halved every 11 years. By taking this into account, one can see detectable changes in levels of carbon-14 in modern DNA. Most molecules of the cell will turn over all the time. But DNA is a material that does not exchange carbon after cell division, so it serves as a time capsule for carbon. Other approaches have tried to assess cell age in the past, and have included looking at the length of DNA 'caps' known as telomeres. But we currenty know too little about telomeres for this to be much use. Shortened telomeres may mean the cell was generated more recently, but how recently we don't know because we don't have a timescale for it. Frisén and his team looked at tissue samples from more than a dozen deceased subjects, about half of whom were born after the mid-1960s. By measuring carbon-14 in their DNA, they can pinpoint individual cells' birth dates to within 2 years. All of the samples taken from the visual cortex, the region of the brain responsible for processing sight, were as old as the subjects themselves, supporting the idea that these cells do not regenerate. The reason these cells live so long is probably that they need to be wired in a very stable way. This could help to address long-standing questions of just how rigid or just how flexible our brains are at the cellular level. Other brain cells are more short-lived^ref. In an average person of some 30 years of age, intestinal cells are about a decade old and skeletal cells a bit older than that. Cells that endure a great deal of physical stress, such as red blood cells, are known to turn over every few months. The research team believes that dating cells using carbon-14 will shed light on the role of cell death in cognitive disorders. Previous studies have suggested that a lack of proper regeneration of some brain cells can cause depression
Web resources :
• dmoz Open Directory Project (ODP) : Neurobiology
• Department of Neurobiology and Behavior at Cornell University
• The Behaviourome / Mental Map Project
• NINDS Gensat BAC transgenic project : gene expression atlas of the CNS of the mouse based on bacterial artificial chromosomes (BACs).
• Neurofizz
• DopaNet by EMBL-EBI
• Allen Brain Atlas by Allen Institute for Brain Science
• central nervous system (CNS) / pars centralis systematis nervosi / systema nervosum centrale (see also pathology of the central nervous system) : consisting of the brain and spinal cord

Nervous system organogenesis :
• neuroectoderm : the portion of the ectoderm of the early embryo that gives rise to the CNS and PNS, including some glial cells
• neuroderm / neural ectoderm : that portion of the ectoderm which develops into the neural tube
• neural plate : the thickened plate of ectoderm in the embryo from which the neural tube develops.
• medullary or neural groove : the groove produced by the invagination of the neural plate of the embryo during the process of formation of the neural tube
• neural, medullary or cerebromedullary tube : the neuroepithelial tube developed from the neural plate and forming the CNS of the embryo
• floor or ventral plate / bodenplatte : the unpaired ventral longitudinal zone of the neural tube, forming the floor of that tube
• deck, dorsal or roof plate / deckplatte : the unpaired dorsal longitudinal zone of the neural tube, forming the roof of that tube
• neuropore : the open anterior end (foramen anterius) or the open posterior end (foramen posterius) of the neural tube of the early embryo. These openings gradually close during the fourth week as the primordial spinal cord develops.
• rostral or anterior neuropore : the embryonic opening in the anterior (or rostral) portion of the forebrain, which closes at the 20-somite stage (about 25 days)
• caudal or posterior neuropore : the embryonic opening at the posterior (or caudal) end of the neural tube, which closes by about the 25-somite stage (about 27 days).
• external or outer limiting membrane : a membrane investing the external surface of the embryonic neural tube
• neural crest : a cellular band dorsolateral to the neural tube that gives origin to the cranial and spinal ganglia and many other structures.
• ectomesenchyme : mesenchyme originating from the ectoderm, particularly from the neural crest.
• amine precursor uptake and decarboxylation (APUD) cells : a diffuse group of cells, many originating in the neural crest, that share certain cytochemical and ultrastructural characteristics and are found scattered throughout the body; types include :
• sympathoblast / sympathetoblast / sympathicoblast / sympathetic neuroblast : a pluripotential cell in the embryo that will develop into a sympathetic nerve cell or a chromaffin cell
• sympathogonia : undifferentiated embryonic cells which develop into sympathetic cells
• chromaffin cells / pheochrome cells / pheochromocytes stain readily with chromium salts, their cytoplasmic chromaffin granules taking on a characteristic brown color
• argentaffin cells (sensu latu) stain readily with silver salts
• argentaffin cells (sensu strictu) reduce silver without pretreatment (more common in gastroenteric system, overlapped with chromaffin cells)
• argyrophilic cells require prior exposure to a reducing substance, otherwise they cannot be seen at optic microscopy (more coomon
• melanocytes
• adrenal medulla
• paraganglia / chromaffin body / pheochrome body : a collection of chromaffin cells, derived from neural ectoderm, occurring elsewhere than in the adrenal medulla, usually near the sympathetic ganglia and in relation to the aorta and its branches (coccygeal gland and carotid gland). Most, if not all, paraganglia secrete epinephrine or norepinephrine.
• corpora paraaortica / aortic, para-aortic, vagal, or Zuckerkandl's bodies / glomera aortica : exclaves of glandular cells of sympathetic origin (chromaffin cells) found near the sympathetic ganglia along the aorta in the abdominal cavity; they serve as chemoreceptors responsive to O₂, CO₂, and H⁺ concentration, that help to control respiration
• enteroendocrine cells / basal granular cells found scattered throughout the gastrointestional epithelium, mainly at the base of the epithelium; their numerous small secretory granules are concentrated chiefly between the nucleus and the cell base
• enterochromaffin cells are chromaffin and argentaffin (sensu latu) enteroendocrine cells, which are sites of synthesis and storage of serotonin
• enteroendocrine argyrophilic cells are located in the fundic and pyloric glands between the basement lamina and zymogenic cells
• hypothalamus
• hypophysis
• C- or parafollicular cells of thyroid
• oxyphile cells of parathyroids
• Kulchitsky cells
They can produce :
• biogenous amines
• epinephrine
• norepinephrine
• dopamine
• serotonin
• histamine
• kallikrein
• peptide hormones
• gastrin
• ghrelin
• ACTH
• GHRH
• bradykinin
• enkephalin
• somatostatin (SST)
• neurotensin
• motilin
• secretin
• substance P (SP)
• pancreatic polypeptide (PP)
• cholecystokinin (CCK)
• gastric inhibitory peptide (GIP)
... the actions of which may affect :
• contiguous cells
• neurocrine activity (chemical synapses)
• neuroendocrine activity (blood vessels between neurons)
• nearby groups of cells
• paracrine activity
• epicrine activity (e.g. melanocytes)
• distant cells
• endocrine activity (blood vessels between cells)
• exocrine activity (in some animals)
The behaviour of neural crest derivatives in Africans is different from that seen in Caucasians, both in terms of physiology and pathology. The most obvious variation is in the depth of pigmentation of the skin, but most diseases of neural crest derived tissues show differences between Black and White subjects. The reason for these differences are not readily apparent but appear to be of genetic rather than environmental origin.
Their neoplastic degeneration leads to apudomas / carcinoids.
• prosencephalon / forebrain : the most anterior of the 3 primary brain vesicles in the embryo, later dividing into 2 brain vesicles...
• diencephalon (posterior)
• telencephalon / endbrain (anterior, consisting of the anterolateral evaginations of the prosencephalon, together with the median, unpaired portion, the lamina terminalis; from it the cerebral hemispheres are derived)
• paraphyseal arch : the embryonic structure in the roof of the third ventricle of vertebrates from which develops the paraphysis / paraphyseal body (a thin-walled derivative of the roof plate of the telencephalon, present only temporarily in the human embryo and fetus)
• mesencephalon : the middle of the 3 primary brain vesicles in the embryo
• rhombencephalon / hindbrain : the most posterior of the 3 primary brain vesicles in the embryo, later dividing into 2 brain vesicles...
• metencephalon / afterbrain (anterior)
• myelencephalon (posterior)
• conariohypophyseal tract : a portion of the cavity of the embryonic brain connecting the pineal body and the pituitary gland
• velum transversum : a transverse fold of the tela choroidea marking the boundary between the diencephalon and the telencephalon in the embryonic brain
• myelomere : one of the segments of the developing brain and spinal cord
• cerebral, cervical or nuchal flexure / head or neck bend : a bend in the neural tube of the embryo at the junction of the brain and spinal cord
• pontine flexure : a flexure in the hindbrain of the embryo; called also basicranial f.
• cephalic, cranial or mesencephalic flexure : the curve in the midbrain (mesencephalon) of the neural tube
• varolian bend : the third cerebral flexure in the developing fetus
Cell types :
• neuron / nerve cell : any of the 100 billion conducting cells of the nervous system. A typical neuron consists of a cell body, containing the nucleus and the surrounding cytoplasm (perikaryon); several short radiating processes (dendrites); and one long process (the axon), which terminates in twiglike branches (telodendrons) and may have branches (collaterals) projecting along its course. The axon together with its covering or sheath forms the nerve fiber
• Nissl bodies, granules or substance / chromophilous bodies / chromophilic or chromatic granules / tigroid bodies or substance : large granular basophilic bodies found in the cytoplasm of neurons, composed of RER and free polyribosomes


Morphology : they vary so greatly in structure that there are an estimated 10,000 different types.
• stellate cell : cell having a star-shaped appearance produced by numerous processes that extend in different directions such as granule cells in the granular layers of the cerebral cortex and cerebellar cortex.
• Golgi's cells
• Golgi type I neuron or cell : pyramidal neurons with very long axons, that leave the gray matter of the CNS, traverse the white matter, and terminate in the periphery
• Golgi type II neuron or cell : stellate neurons with short axons that do not pass out of the gray matter in which the cell body lies, and are especially numerous in the cerebral cortex, cerebellar cortices and in the retina.
• Gierke's or Rolando's cells : small, deeply staining Golgi type II neurons that constitute the chief cells of Rolando's gelatinous substance
• Rolando's cells : the ganglion cells of Rolando's gelatinous substance
• apolar cell : a neuron with no processes or poles
• unipolar neuron : a neuron with one process only
• pseudounipolar neuron : a unipolar neuron, almost always a primary sensory neuron, that was originally bipolar but whose 2 processes fused during development to form a single process that bifurcates at a distance from the cell body. One branch is structurally an axon with a myelin sheath but functions as a dendrite, with afferent conduction originating in a nerve ending.
• bipolar neuron : a neuron having 2 processes, one projecting from each end of the cell body; these may be either one axon and one dendrite or 2 dendrites.
• Beale's ganglion cells : bipolar cells with one process coiled around the other; found in cardiac ganglia.
• multipolar or polymorphic neuron : a neuron with several to many processes; such neurons vary in shape, depending on the arrangement of the processes, with pyramidal and stellate (star) shapes being common
• spiny neuron : a neuron whose dendrites have many spines (gemmules), such as a Golgi type I neuron.
A typical neuron makes contact with about 2,000 other neurons.
Released neurotransmitter :
• adrenergic fibers : nerve fibers, usually sympathetic, that release epinephrine or related substances as neurotransmitters
• peptidergic fibers : nerve fibers that secrete neuropeptides as neurotransmitters.
• aminergic fibers : nerve fibers that liberate one of the biogenic amines at a synapse as a nerve impulse passes; nearly all nerve fibers are this type
• cholinergic fibers : nerve fibers that liberate acetylcholine as a neurotransmitter.
Fiber structure :
• myelinated or medullated nerve fibers : grayish white nerve fibers whose axons are encased in a myelin sheath, which may in turn be enclosed by a neurilemma
• substantia alba / white substance / white matter of nervous system : the white nervous tissue, constituting the conducting portion of the brain and spinal cord; it is composed mostly of myelinated nerve fibers arranged in anterior, posterior, and lateral funiculi
• puncta vasculosa : minute red spots marking the cut surface of the white substance of the brain, produced by blood from divided vessels
• centrum semiovale / semioval center : the white matter of the cerebral hemispheres which underlies the cerebral cortex and which, in horizontal sections superior to the corpus callosum, has a semioval shape; it contains projection, commissural, and association fibers.
• substantia grisea / gray substance / gray matter of nervous system: the gray nervous tissue composed of nerve cell bodies, unmyelinated nerve fibers, and supportive tissue
• varicose fibers : certain myelinated fibers which have no neurilemma; after death a fluid accumulates between the myelin and the axon, giving the fibers a varicose appearance.
• Frommann's lines : transverse marks on the axon of a medullated nerve fiber, rendered visible by silver nitrate.
• period lines : a series of light and dark lines occurring in a concentric, repeating pattern in mature myelin: the darker lines (major dense lines) represent the apposition of the inner, cytoplasmic surfaces of the Schwann cell plasma membrane; the lighter lines (intraperiod lines) bisect the spaces between the darker lines, and represent the apposition of the outer surfaces of the membrane.
CNS myelin :
• proteolipid protein 1 (PLP1)
• myelin basic protein (MBP)
• myelin oligodendrocyte protein (MOG)
PNS myelin :
• myelin protein P₀ (MPZ)
• peripheral myelin protein 2 (PMP2) / P₂ protein
• peripheral myelin protein 22 (PMP22)
• gangliosides
• GM₁
• GM₂
• GM₃
• GQ_1b
• GD₃
• GD₂
• myelin-associated glycoprotein (MAG)
• unmyelinated or nonmedullated nerve fibers : nerve fibers (axons) that lack the myelin sheath but may be enclosed by a neurilemma
• vasomotor fibers : unmyelinated nerve fibers going chiefly to arteriolar muscles.
• gray fibers : unmyelinated nerve fibers, found largely, but not exclusively, in the sympathetic nerves.

Lloyd-Chang classification	Erlanger-Gasser classification	Ø [mm]	conduction rate [m/s]
Ia  Ib	Aa fibers (a motoneurons and proprioceptive fibers)	(13-22)  17  16	70-120
II	Ab fibers (b motoneurons and proprioceptive fibers)  Ag fibers / fusimotor fibers / fusimotor axons (g motoneurons that innervate the intrafusal fibers of the muscle spindle)	8-13  8	30-70 15-40
III	Ad fibers (myelinated fibers that respond to pressure, temperature, or chemical stimuli, conducting from the cutaneous tissues the initial stimulus perceived as the primary painful event)  B fibers (myelinated preganglionic autonomic axons; these include only efferent fibers)	3	< 30 3-15
IV	C fibers (unmyelinated nerve fibers found as postganglionic (efferent) fibers of the autonomic nervous system, and as afferent fibers at posterior roots, receiving impulses from free nerve endings that act as thermoreceptors, nociceptors, and interoceptors)	0.3-1.3	0.6-2.3

Function :
• homodesmotic fibers : nerve fibers connecting similar structures of the CNS
• heterodesmotic fibers : nerve fibers connecting dissimilar structures of the CNS
• central neuron : a neuron which belongs entirely to the CNS
• fibra projectionis / projection fiber / projection neurofiber / neurofibra projectionis : one of the nerve fibers that connect the cerebral cortex with the subcortical centers, the brain stem, and the spinal cord
• projection neuron : one which serves for the transmission of nervous impulses, whether motor or sensory, between the cerebral cortex and other parts of the nervous system
• integrator cell / interneuron : they have the following functions :
• divergence of afference (from the protagonist to agonist and antagonist muscles). Those in spinal cord are named inhibitory interneurons Ia or Ib according to the sensitive fiber they receive
• convergence on an efference
• inhibition (or excitation) of other interneuronsthat excite (or inhibit) the motoneuron
• presynaptic inhibition of the afference
• reverberating circuit : a neuronal pathway arranged in a circle so that impulses are recycled to cause positive feedback or reverberation
• reverberation : duration of neuronal activity well beyond an initial stimulus due to transmission of impulses along branches of nerves arranged in a circle, permitting positive feedback; it occurs in the brain and perhaps elsewhere and is thought to be related to processes such as learning, memory, and habituation
• automatic rhythmic activities (out of phase excitations between 2 parallel neuronal chains)
• coordination between spinal cord segments (propriospinal fasciculi between cervical and lumbar enlargements allow coordination between upper and lower limbs)
• afferent neuron : any neuron conducting a nerve impulse that originated at a receptor and is proceeding towards the center.
• sensory neuron : any neuron with a sensory function; an afferent neuron conveying sensory impulses.
• primary sensory neuron : a sensory neuron that is the first in an afferent pathway, beginning at the receptor and ending at a synapse with a secondary sensory neuron, often within a nucleus of the CNS. One common type is the pseudounipolar neuron.
• secondary sensory neuron : a sensory neuron that is the second in an afferent pathway, being stimulated at a synapse by a primary sensory neuron and often extending some distance into the CNS
• multisensory neuron : a neuron in the cerebral cortex or subcortical regions that can receive input from more than one sensory modality; the inputs may be simultaneous, reinforcing each other.
• efferent neuron : any neuron conducting a nerve impulse that originated at the center and is proceeding towards the periphery
• motoneuron / motor neuron : a neuron with a motor function; an efferent neuron conveying motor impulses
• upper motoneurons : neurons in the cerebral cortex that conduct impulses from the motor cortex to motor nuclei of the cerebral nerves or to the ventral gray columns of the spinal cord.
• lower motoneurons : peripheral neurons whose cell bodies lie in the ventral gray columns of the spinal cord and whose terminations are in skeletal muscles.
• anterior horn cells : motoneurons whose cell bodies are in the anterior horn of the spinal cord
• a motoneuron : neurons of the anterior spinal cord that give rise to the a fibers which innervate the skeletal muscle fibers
• g motoneuron : neurons of the anterior spinal cord that give rise to the g (fusimotor) fibers which innervate intrafusal fibers of the muscle spindle
• b motoneurons : neurons of the anterior spinal cord that give rise to the beta fibers that innervate extrafusal and intrafusal muscle fibers.
• ultraterminal fiber : the thin unmyelinated twig that is the last ramification of the axon at the motor end plate (the discoid expansion of a terminal branch of the axon of a motor nerve fiber, which apposes the subneural apparatus of a skeletal muscle fiber, forming the neuromuscular junction (NMJ))
• Kühne's terminal plates : the motor end-plates of nerves in the muscle spindles.
• heteronymous motoneurons : those supplying muscles other than the one from which the afferent impulses originate.
• homonymous motoneurons : those supplying the muscle from which the afferent impulses originate.
• neurosecretory cell : any cell with neuron-like properties that secretes a biologically active substance acting on another structure, often at a distant site
• paraganglia
• neuroendocrine cells : the specialized neurons that secrete neurohormones
• cells in the hypothalamus
• mirror neurons may help cognitive scientists explain how children develop a theory of mind (ToM), which is a child's understanding that others have minds similar to their own. Over the years, cognitive scientists have come up with a number of theories to explain how ToM develops. The "theory theory" and "simulation theory" are currently 2 of the most popular. Theory theory describes children as budding social scientists. The idea is that children collect evidence -- in the form of gestures and expressions -- and use their everyday understanding of people to develop theories that explain and predict the mental state of people they come in contact with. Vittorio Gallese, a neuroscientist at the University of Parma in Italy and one of original discovers of mirror neurons, has another name for this theory: he calls it the "Vulcan Approach," in honor of the Star Trek protagonist Spock, who belonged to an alien race called the Vulcans who suppressed their emotions in favor of logic. Spock was often unable to understand the emotions that underlie human behavior. Gallese himself prefers simulation theory over this Vulcan approach. Simulation theory states that we are natural mind readers. We place ourselves in another person’s "mental shoes," and use our own mind as a model for theirs. Gallese contends that when we interact with someone, we do more than just observe the other person’s behavior. He believes we create internal representations of their actions, sensations and emotions within ourselves, as if we are the ones that are moving, sensing and feeling. Many scientists believe that mirror neurons embody the predictions of simulation theory. We share with others not only the way they normally act or subjectively experience emotions and sensations, but also the neural circuits enabling those same actions, emotions and sensations: the mirror neuron systems. However the 2 theories are not mutually exclusive. If the mirror neuron system is defective or damaged, and our ability to empathize is lost, the observe-and-guess method of theory theory may be the only option left. Some scientists suspect this is what happens in autistic people, whose mental disorder prevents them from understanding the intentions and motives of others. The idea is that the mirror neuron systems of autistic individuals are somehow impaired or deficient, and that the resulting "mind-blindness" prevents them from simulating the experiences of others. For autistic individuals, experience is more observed than lived, and the emotional undercurrents that govern so much of our human behavior are inaccessible. They guess the mental states of others through explicit theorizing, but the end result is a list -- mechanical and impersonal -- of actions, gestures and expressions void of motive, intent, or emotion. Several labs are now testing the hypothesis that autistic individuals have a mirror neuron deficit and cannot simulate the mental states of others. One recent experiment by Hugo Theoret and colleagues at the University of Montreal showed that mirror neurons normally active during the observation of hand movements in non-autistic individuals are silent in those who have autism.
• glial or neuroglial cells : each one of the 500 billion cells of the human adult nervous sytem. See also blood-brain barrier (BBB) and blood-CSF barrier
• neuroglial fiber : one of the fibrillar structures embedded in the cytoplasm and expansions of neuroglial cells, particularly fibrous astrocytes
• corpora amylacea
• microglia : microglial cells / Hortega cells
• gitter cell / compound granule or granular corpuscle : a microglial cell that is globular and swollen after having phagocytized debris from cells destroyed pathologically in the CNS
• macroglia : neuroglial cells of ectodermal origin
• astroglia consisting of astrocytes / Cajal cells / spider cells
• fibrillary or fibrous astrocytes : astrocytes found mainly in the white matter of the brain, having long, thin, infrequently branched cytoplasmic processes containing numerous fibrillar structures.
• plasmatofibrous astrocytes : astrocytes found at the junction of the gray and white matter of the brain; the cytoplasmic processes extending into the white matter are fibrous and those extending into the gray matter are protoplasmic.
• protoplasmic astrocytes / mossy cells : astrocytes found mainly in the gray matter of the brain, having many branching, thick cytoplasmic processes.
• pericapillary end foot / perivascular foot / sucker foot or process / vascular foot plate : a pyramidal expansion of a process of an astrocyte against the wall of a capillary in the CNS
Cajal-Retzius cells are critical in cortical lamination, but very little is known about their origin and development. The homeodomain transcription factor Dbx1 is expressed in restricted progenitor domains of the developing pallium: the ventral pallium (VP) and the septum. 2 subpopulations of Reelin⁺ Cajal-Retzius cells are generated from Dbx1⁺ progenitors. VP- and septum-derived Reelin⁺ neurons differ in their onset of appearance, migration routes, destination and expression of molecular markers. Together with reported data supporting the generation of Reelin⁺ cells in the cortical hem, Cajal-Retzius cells are generated at least at 3 focal sites at the borders of the developing pallium and are redistributed by tangential migration. Distinct Cajal-Retzius subtypes exist and that their presence in different territories of the developing cortex might contribute to region-specific properties^ref.
• oligodendroglia : the non-neural cells of ectodermal origin forming part of the adventitial structure (neuroglia) of the CNS; projections of the surface membrane of each of these cells (oligodendrocytes) fan out and coil around the axon of many neurons to form myelin sheaths in the white matter. With microglia, they form the perineuronal satellites in the gray matter
• caudate cells : neuroglial cells of the gray matter having several streaming prolongations like the tail of a comet
• neurofibra / nerve fiber / fiber / fibra / neurofiber : a slender process of a neuron; the term is often synonymous with axon. Nerve fibers are classified on the basis of the presence or absence of a myelin sheath as myelinated or unmyelinated. In the terminology for types of nerve fibers, the word nerve is frequently dropped
• T fiber : a nerve fiber that branches at right angles from the axon, as seen in pseudounipolar neurons.
• bundle : a collection of nerve fibers
• fasciculus : a tract, bundle, or group of nerve fibers that are more or less associated functionally
• nucleus : a group of nerve cells ordinarily located within the CNS and bearing a direct relationship to the fibers of a particular nerve.
• terminal nucleus / nucleus terminationis / terminator nucleus : any of the groups of nerve cells within the CNS upon which the axons of primary afferent neurons of various cranial nerves synapse.
• tract / tractus : a collection or bundle of nerve fibers having the same origin, function, and termination
• motor tract : any bundle of nerve fibers conveying motor impulses from the CNS to a muscle.
• sensory tract : any bundle of nerve fibers conveying sensory impulses from a peripheral receptor to the CNS
• stria : a general term for such longitudinal collections of nerve fibers in the brain.
• lemniscus / fillet : a band or bundle of sensory fibers in the CNS
• nervous stem cells
Macroscopic anatomy :
• ventricles of the brain : the cavities within the brain which are filled with CSF. They are lined by ependyma which, in certain regions, is invaginated by vascular fringelike infoldings of blood vessels of the pia mater that form tufted projections termed choroid plexuses :
• plexus choroideus ventriculi lateralis / choroid plexus of lateral ventricle : in the floor of the pars centralis and the roof of the temporal horn of the lateral ventricle
• plexus choroideus ventriculi quarti / choroid plexus of fourth ventricle : in the roof of the posterior part of the fourth ventricle and extending into and through the lateral recesses
• plexus choroideus ventriculi tertii / choroid plexus of third ventricle : in the roof of the third ventricle
• villi of choroid plexus : tiny hairlike processes of varying sizes along the edges of the choroid plexus, containing blood vessels; their exact function is unknown
• sand bodies / acervulus / brain sand : the mass of gritty matter lying in or near the pineal body, the choroid plexus, and other parts of the brain
Cell types : choroidal plexus cell / ciliated ependymal cell / ependymocyte. Tight junctions between ependymocyte allow CSF to be eventually reabsorbed by transcellular route only.
• tanycyte : a modified ependymal cell of the median eminence, having a body that lies near the third ventricle and sending out processes that extend to the capillary plexus of the portal circulation. Its function is unknown, but it may transport hormones from the cerebrospinal fluid into the portal circulation or from hypothalamic neurons to the CSF. Tanycytes are bipolar cells bridging the CSF to the portal capillaries and may link the CSF to neuroendocrine events. During the perinatal period a subpopulation of radial glial cells differentiates into tanycytes, a cell lineage sharing some properties with astrocytes and the radial glia, but displaying unique and distinct morphological, molecular, and functional characteristics. 4 populations of tanycytes, a₁, a₂, b₁, and b₂, can be distinguished. These subtypes express differentially important functional molecules, such as glucose and glutamate transporters; a series of receptors for neuropeptide and peripheral hormones; secretory molecules such as TGFs, PGE₂, and the specific protein P85; and proteins of the endocytic pathways. This results in functional differences between the four subtypes of tanycytes. Thus, a₁, a₂ tanycytes do not have barrier properties, whereas b₁, and b₂ tanycytes do. Different types of tanycytes use different mechanisms to internalize and transport cargo molecules; compounds internalized via a clathrin-dependent endocytosis would only enter tanycytes from the CSF. There are also differences in the neuron-tanycyte relationships; b₁ and b₂ tanycytes are innervated by peptidergic and aminergic neurons, but a₁, a₂ tanycytes are not. Important aspects of the neuron-b₁ tanycyte relationships have been elucidated. Tanycytes can participate in the release of GnRH to the portal blood by expressing estrogen receptors, absorbing molecules from the CSF, and providing signal(s) to the GnRH neurons. Removal of tanycytes prevents the pulse of GnRH release into the portal blood, the peak of luteinizing hormone, and ovulation. The discovery in tanycytes of new functional molecules is opening a new field of research. Thus, thyroxine deiodinase type II, an enzyme generating T₃ from thyroxine, appears to be exclusively expressed by tanycytes, suggesting that these cells are the main source of brain T₃. GLUT-2, a low-affinity transporter of glucose and fructose, and ATP-sensitive K⁺ channels are expressed by tanycytes, suggesting that they may sense CSF glucose concentrations.
20 mL/hr (500-600 mL/day) of cerebrospinal fluid (CSF) are continuously secreted by :
• choroid plexuses supplied by the choroidal arteries (70%)
• capillary ultrafiltration within nervous parenchyma and arachnoid (30%)
Its overall volume (130-140 mL) is renewed every 6-8 hours. Circulation is supported by input pressure and pulsation of choroid arteries. CSF decreases encephalon weight by 30-folds thanks to buoyancy and deceleratres it during violent displacements. Further it carries hormones and releasing factors and partecipates in removal of drugs and catabolytes from the encephalon.
Monro-Kellie doctrine : the central nervous system and its accompanying fluids are enclosed in a rigid container whose total volume tends to remain constant; an increase in volume of one component, e.g., brain, blood, or cerebrospinal fluid, will elevate pressure and decrease the volume of one of the other elements.
CSF/serum quotients quotients (Q) are dimensionless measures of the CNS concentrations, independent of the blood level variation (a higher CSF value corresponds to the higher serum concentrations and the quotients remain constant)
• parameters (see also pathological alterations)
• look
• color
• density = 1004-1008
• water = 99%
• pH = 7.4
• [chloride]_CSF = 120-130 mEq/L = 710-780 mg/dl
• [chlorine]_CSF = 430-460 mg/dl
• [calcium]_CSF = 5 mg/dl
• [sodium]_CSF = 337 mg/dl
• [potassium]_CSF = 19.2 mg/dl
• [iron]_CSF = 35 mg/dl
• [phosphate]_CSF = 3 mg/dl
• [lactate]_CSF = 15 mg/dl
• [pyruvic acid]_CSF = 1 mg/dl
• [WBC]_CSF = 2-3 / mL
• lymphocytes (expecially T lymphocytes) = 60-70%
• monocytes = 30-50%
• neutrophils = 1-3%
• [RBCs]_CSF < 1,000 / mL
• [pigments]_CSF appears after centrifugation
• [oxyhemoglobin]_CSF = 0
• [bilirubin]_CSF = 0
• xanthochromic index = A_{416 nm (oxyhemoglobin)} + A_{460 nm (bilirubin)}  = 0-0.05 Abs
• glycorrhachy = [glucose]_CSF : 35-70 mg / dL = 2.8-4.2 mmol/L = 50-60 mg%. Glucose represents 90% of reducing substances in CSF
• total lipids = 1.2 mg/dl
• total cholesterol = 0.4 mg/dl
• esterified cholesterol = 0.296 mg/dl
• free cholesterol = 0.119 mg/dl
• amino acids = 4-6 mg/dl
• total nitrogen = 17.7 mg/dl
• urea = 8.6-26 mg/dl
• uric acid = 0.5-2.6 mg/dl
• proteinorrhachy = [proteins]_CSF : 16-54 mg/dL = 20-40 mg/dl
• ventricular CSF : 5-15 mg/dL
• cisternal CSF : 15-25 mg/dL
• lumbar CSF : 15÷45 mg /dL
• [albumin]_CSF = 10-30 mg/dL = 18-30 mg/dl
• albumin quotient (Q_alb) = [albumin]_CSF/[albumin]_plasma < 0.008 (a parameter for the blood-brain barrier (BBB) function as albumin is produced only outside the BBB and may come only from blood)
• the blood-derived proteins in CSF follow a hyperbolic function which depends primarily on the molecular size of the proteins
• brain-derived proteins
• from neurons and glial cells like tau protein, neuron-specific enolase (NSE), and S100 protein all enter CSF, primarily in the ventricular and cisternal space. Their concentration between normal ventricular and lumbar CSF decreases (in contrast to blood proteins), and in the case of pathological decrease of CSF flow rate, the mean concentration in lumbar CSF remains unchanged
• primarily leptomeningeal protein increase between normal ventricular and lumbar CSF, and in the case of pathologically reduced CSF flow rate, they increase linearly in lumbar CSF
• proteins with particular conditions, including additional blood-derived fractions like transthyretin or sICAM, need to be evaluated with reference to the albumin CSF/serum quotient to avoid misinterpretation
• globulins = 5-8 mg%
• [IgG]_CSF : 1-4 or 0-8.6 mg/dL.
• g globulin % fraction = [g globulin]_CSF/[total protein]_CSF < 14% by eletrophoresis on cellulose acetate with previous concentration
• Fishman ratio (IgG%) = [IgG]_CSF/[total protein]_CSF < 15%
• Tibbling-Link ratio / IgG quotient (Q_IgG) = [IgG]_CSF/[IgG]_plasma = 0-0.66
• Olsson-Pettersson ratio = Q_IgG / Q_alb < 0.7
• Reiber's plot^ref : (Q_IgG ^. 1000) plotted vs. (Q_alb ^. 1000)
• intratechal IgG-synthesis
• Tourtellotte-Boce ratio = [IgG] syn = 0-6.47 mg/die
• Reiber ratio = [IgG] p = 0-0.32 mg/dL
• Reiber & Felgenhauer : [IgG]_CSF (mg/l)= [Q_IgG - Q_lim (IgG)] ^. /[IgG]_plasma
• Q_lim = a/b ^. (Q_alb² + b² - c)^-1/2, where a, b, and c are constants.
• antigen-specific antibody index (AI)^ref =
• = (specific IgM_CSF / specific IgM_serum) / (total IgM_CSF / total IgM_serum) = Q_{specific IgM} / Q_IgM
• = (specific IgG_CSF / specific IgG_serum) / (total IgG_CSF / total IgG_serum) = Q_{specific IgG} / Q_IgG
• In case of detection of antibody production, Q_{total IgM} (Q_{total IgG} response) is compared to its upper limit (Q_lim). If Q_{total Ig} is higher than Q_lim, which is common in disorders like MS, corrected AI is calculated by Q_lim instead of Q_{total Ig}
• [IgA]_CSF : 0-0.6 mg/dL
• [IgM]_CSF : 0-0.2 mg/dL
• antibody index (AI) detects intratechal antibody synthesis
• intratechal fraction (IF)
• cerebrospinal or intracranial pressure (ICP) : the pressure in the space between the skull and the brain, i.e., the pressure or tension of the subarachnoidal CSF, normally = 100–150 mmH₂O = 10-15 mmHg as measured Claude's spinal manometer, with respiratory waves
• in seated position (increasing from higher to lower levels)
• -10 - +10 mmH₂O in cerebellomedullary cistern
• + 50 mmH₂O in dorsal tract
• 250-300 mmH₂O in lower lumbar tract
• in lateral decubitus : 150-200 mmH₂O at all levels
• Lundberg (or B) waves, defined as repetitive changes in intracranial pressure (ICP) occurring at frequencies of 0.5 to 2 waves/min, have been attributed to cerebral blood flow fluctuations induced by central nervous system pace-makers or cerebral pressure autoregulation.
• cephalorachidian, cephalorhachidian or cerebrospinal index : the figure obtained by multiplying the final cerebrospinal pressure by the quantity of fluid withdrawn in spinal puncture and then dividing by the initial pressure.
The cavum septi pellucidi, to which the term ventricle is sometimes applied, is not a true ventricle.
• ventriculus lateralis cerebri / lateral ventricle of cerebrum : the cavity in each cerebral hemisphere (ventriculus sinister cerebri and ventriculus dexter cerebri), derived (developed) from the cavity of the embryonic neural tube; it consists of :
• pars centralis ventriculi lateralis / central part of lateral ventricle / body of lateral ventricle : the part of the lateral ventricle found within the parietal lobe; it communicates with the frontal, occipital, and temporal horns
• 3 horns :
• cornu anterius or frontale ventriculi lateralis / anterior or frontal horn of lateral ventricle : the part of the lateral ventricle that extends forward from the pars centralis into the frontal lobe
• cornu inferius or temporale ventriculi lateralis / inferior or temporal horn of lateral ventricle : the part of the lateral ventricle that extends downward and forward from the pars centralis behind the thalamus and into the temporal lobe
• cornu occipitale or posterius ventriculi lateralis / occipital or posterior horn of lateral ventricle : the part of the lateral ventricle that extends backward from the pars centralis into the occipital lobe :
• bulbus cornus occipitalis or posterioris ventriculi lateralis / bulb of occipital or posterior horn of lateral ventricle : an eminence in the upper part of the medial wall of the occipital horn of the lateral ventricle, above the calcar avis, produced by the splenial fibers of the forceps frontalis as they pass posteriorly into the occipital lobe
They are separated from each other by the septum pellucidum.
• fissura choroidea ventriculi lateralis / choroid fissure of lateral ventricle : the medially located line in the lateral ventricle along which the choroid plexus invaginates
• occipital eminence : a ridge on the lateral ventricle of the embryonic brain, corresponding to the occipital fissure in the adult.
• eminentia collateralis ventriculi lateralis / collateral eminence of lateral ventricle : an elevation in the floor of the temporal horn of the lateral ventricle, produced by the collateral sulcus.
• tela choroidea ventriculi lateralis / tela choroidea of lateral ventricle : the lateral extension of the tela choroidea of the third ventricle into the choroid fissure of the lateral ventricle of the brain; from it, vascular folds invaginate the ventricular ependyma to form the choroid plexus of the lateral ventricle
• lamina affixa : the narrow strip of ependyma overlying the thalamostriate vein and stria terminalis in the central part of the lateral ventricle.
• glomus choroideum / choroid glomus / choroidal enlargement : an enlargement of the choroid plexus of the lateral ventricle where the inferior horn joins the central part
• interventricular foramen / foramen interventriculare / foramen of Monro : a passage through which each of the lateral ventricles and the third ventricle communicate, through which also the choroid plexuses of the lateral ventricles become continuous with that of the third ventricle
• ventriculus tertius cerebri / third ventricle of cerebrum : a narrow cleft below the corpus callosum, within the diencephalon between the 2 thalami. Its floor is formed by the hypothalamus, its anterior wall by the lamina terminalis, and its roof by ependyma
• velum interpositum cerebri / tela choroidea ventriculi tertii / tela choroidea of third ventricle : a double layer or fold of pia mater which, together with the ventricular ependyma, forms the roof of the third ventricle; from the lower fold 2 vascular fringes invaginate the roof to form the choroid plexuses.
• [postchiasmatic or postfundibular eminence : an inconstant protuberance on the floor of the third ventricle posterior to the optic chiasm]
• aqueductus cerebri or mesencephali / aqueduct of mesencephalon / iter or aqueduct of Sylvius / aqueductus / cerebral aqueduct : the narrow channel in the mesencephalon that connects the third and fourth ventricles
• [Verga's sixth ventricle / cavum psalterii : an occasional space (not a true ventricle) between the corpus callosum and the fornix]
• ventriculus quartus cerebri / fourth ventricle of cerebrum : an irregularly shaped cavity in the rhombencephalon, between the medulla oblongata, the pons, and the isthmus in front, and the cerebellum behind; it is continuous with the central canal of the cord below and with the cerebral aqueduct above.
• tegmen ventriculi quarti / roof of fourth ventricle : the superior part of the ventricle, formed by the superior and inferior medullary vela.
• striae medullares ventriculi quarti / medullary striae of fourth ventricle / striae medullares fossae rhomboideae : bundles of white fibers coursing transversely across the floor of the fourth ventricle; they arise from the arcuate nuclei, pass dorsally close to the midline, and after having reached the fourth ventricle finally enter the inferior cerebellar peduncle
• vestibular area : a rounded triangular elevation lateral to foveae of the fourth ventricle over which pass the striae medullares; it extends into the lateral recess, where it forms the auditory, or acoustic, tubercle.
• sulcus medianus ventriculi quarti / median sulcus of fourth ventricle : a median groove in the floor of the fourth ventricle
• calamus scriptorius : the lowest portion of the floor of the fourth ventricle, shaped like a pen when viewed from the dorsal side and situated between the restiform bodies
• eminentia medialis fossae rhomboideae / medial eminence of rhomboid fossa / eminentia teres / terete eminence : an eminence in the medial part of the floor of the fourth ventricle, bounded laterally by the sulcus limitans and produced by the facial colliculus and the trigone of the hypoglossal nerve
• tela choroidea ventriculi quarti / tela choroidea of fourth ventricle : a double layer or fold of pia mater between the cerebellum and the lower part of the roof of the fourth ventricle; the anterior layer of the fold, together with the ventricular ependyma, contains vascular fringes which constitute the choroid plexus.
• velum medullare inferius or posterius / caudal, inferior, or posterior medullary velum / velum of Tarinus : either of two thin layers of white substance symmetrically located on the sides of the nodule of the vermis; their internal surface forms the lower wall of the lateroposterior recess of the fourth ventricle. On the sides the velum is continuous with the pedunculus flocculi and the taenia, and anteriorly it is fused with the choroid plexus
• velum medullare rostralis or superius / anterior, rostral or superior medullary velum : a thin layer of white substance forming the roof of the superior part of the fourth ventricle, and extending from the tectal lamina in front to the fastigium behind, and between the superior cerebellar peduncles
• decussatio fibrarum nervorum trochlearium / decussation of trochlear nerve fibers / decussatio trochlearis / decussatio nervorum trochlearis / trochlear decussation : the crossing of the fibers of the trochlear nerves in the superior medullary velum
• frenulum veli medullaris superioris / frenulum of superior medullary velum / frenulum of cranial medullary velum / frenulum of rostral medullary velum / frenulum veli medullaris cranialis / frenulum veli medullaris rostralis : a median ridge that descends upon the rostral medullary velum from between the inferior colliculi
From the fourth ventricle the CSF flows into :
• canalis centralis medullae spinalis / central canal of spinal cord (20%) : a small canal extending throughout the length of the spinal cord, lined by ependymal cells. Above, it continues into the medulla oblongata, where it opens into the fourth ventricle.
• ventriculus terminalis medullae spinalis / terminal ventricle of spinal cord : a saclike expansion of the central canal of the spinal cord within the conus medullaris.
• subarachnoid space (80%) via ...
• apertura lateralis ventriculi quarti / lateral aperture of fourth ventricle / foramen of Luschka or of Key and Retzius : an opening at the end of each lateral recess
• apertura mediana ventriculi quarti / median aperture of fourth ventricle / foramen of Magendie : a deficiency in the lower portion of the roof
• cisternae subarachnoideae / subarachnoid cisterns : localized enlargements of the subarachnoid space, occurring in areas where the dura mater and arachnoid do not closely follow the contour of the brain with its covering pia mater, and serving as reservoirs of CSF
• cisterna cerebellomedullaris posterior / posterior cerebellomedullary cistern / cisterna magna / great or posterior cistern : between the inferior surface of the cerebellum and the posterior surface of the medulla oblongata, and continuous below with the spinal subarachnoid space. It can be tapped by means of a needle inserted through the posterior atlanto-occipital membrane (cisternal puncture)
• cisterna chiasmatica / chiasmatic cistern / cistern of chiasma : between the optic chiasma and the rostrum of the corpus callosum
• cisterna fossae lateralis cerebri / cisterna fossae Sylvii / cistern of fossa of Sylvius / cistern of lateral cerebral fossa : between the arachnoid and the lateral cerebral fossa
• cisterna retrothalamica : the subarachnoid space posterior to the thalamus
• cisterna medialis pontis
• cisterna lateralis pontis
• cisterna venae magnae cerebri Galeni : the superior confluent of the subarachnoid space, lying in the angle between the splenium of the corpus callosum and the superior surfaces of the cerebellum and mesencephalon, and containing the great vein of the cerebrum.
• cisterna ambiens or mesencephalicum : surrounding the midbrain; it connects the cisterna venae magnae cerebri with the cisterna interpeduncularis
• cisterna interpeduncularis / interpeduncular or basal cistern : between the cerebral peduncles
• cisterma lumbaris
Then the CSF is reabsorbed into superior sagittal sinus via arachnoidal granulations.
From the outermost to the innermost layer :
• periosteum
• pericranium / periosteum externum cranii : the external periosteum of the skull
• lamina externa calvariae / external table of calvarium / lamina externa cranii / lamina externa ossium cranii / outer table of skull : the outer compact layer of bone of the flat bones of the skull
• diploë : the loose osseous tissue between the two tables of the cranial bones.
• lamina interna calvariae / internal table of calvaria / lamina interna cranii / lamina interna ossium cranii / inner table of skull : the inner compact layer of bone of the flat bones of the skull
• meninges : the 3 membranes that envelop the brain and spinal cord, some separated by virtual spaces (according to horror vacui theory of human body)
• spatium epidurale / epidural space / cavitas epiduralis / epidural cavity / spatium extradurale / extradural space / spatium peridurale : the space between the dura mater and the internal table (virtual in skull, virtual or real in vertebral canal), containing venous plexuses and fibrous and alveolar tissue
• dura mater / pachymeninx : the outermost, toughest, and most fibrous of the 3 meninges, covering the brain and spinal cord
• dura mater of brain / dura mater cranialis / cranial dura mater / dura mater encephali : the dura mater covering the brain, composed of 2 mostly fused layers ...
• an endosteal outer layer (endocranium) adherent to the inner aspect of the cranial bones, analogous to the periosteum of the bony skeleton
• intradural space : a virtual space
• an inner meningeal layer / properly said dura mater, with a cellular limiting plate
... and the trigeminal ganglion are located between the layers
• falx cerebelli / falx of cerebellum / cerebellar falx : the small fold of dura mater in the midline of the posterior cranial fossa, projecting forward toward the vermis of the cerebellum
• falx cerebri / falx of cerebrum / cerebral falx : the fold of dura mater, sickle-shaped when viewed in sagittal section, that extends downward in the longitudinal cerebral fissure and separates the 2 cerebral hemispheres
• tentorium cerebelli / tentorium of cerebellum : the process of dura mater that supports the occipital lobes and covers the cerebellum. Its internal border is free and bounds the tentorial notch; its external border is attached to the skull and encloses the transverse sinus behind.
• tentorium of hypophysis / diaphragma sellae / sellar diaphragm : a ring-shaped fold of dura mater covering the sella turcica, and containing an aperture for passage of the infundibulum of the hypophysis
See also sinuses of dura mater.
• dura mater of spinal cord / dura mater spinalis / spinal dura mater : the dura mater covering the spinal cord; it is separated from the periosteum of the enclosing vertebrae by an epidural space containing blood vessels and fibrous and areolar tissue
• spatium subdurale / subdural space / subdural cavity : a narrow fluid-containing space, often only a potential space, between the dura mater and the arachnoid
• leptomeninges : the pia mater and arachnoid considered together as one functional unit; the pia-arachnoid. In official nomenclature, arachnoidea mater et pia mater / leptomeninx is used as the preferred term when contrasting this structure with the pachymeninx, which is equivalent to the dura mater.
• arachnoidea mater : a delicate membrane interposed between the dura mater and the pia mater, separated from the pia mater by the subarachnoid space.
• arachnoidea mater cranialis / arachnoid of brain / cranial arachnoid / arachnoidea mater encephali : the arachnoidea covering the brain
• Blake's pouch : a blind pocket of arachnoid connected with the fourth ventricle and the subarachnoid space near the medulla oblongata as a result of abnormal development of the membranous lamina of the auditory tube.
• arachnoidea mater spinalis / spinal arachnoid / arachnoid of spinal cord : the arachnoidea covering the spinal cord
• granulationes arachnoideae / granulationes arachnoideales / arachnoidal granulations or villi / cerebral granulations / meningeal granules / pacchionian bodies, corpuscles, or granulations: small elevations, visible to the naked eye, thought by some to be enlargements of arachnoid villi, which project into the superior sagittal sinus and associated venous lacunae and create slight depressions on the inner surface of the cranium; these granulations are the structures through which CSF is reabsorbed into the blood in the venous system and are lined by endothelium. Tose on roof midline undergo fibrosis in elderlies
• spatium subarachnoideum or leptomeningeum / subarachnoid space or cavity / cavitas subarachnoidea : the space between the arachnoidea mater and the pia mater, containing CSF and bridged by delicate trabeculae
• arachnoid trabeculae / trabeculae arachnoideae : delicate fibrous threads connecting the inner surface of the arachnoid to the pia mater.
• subarachnoidal septum : an incomplete fibrous sheath which lies in the median plane and which connects the arachnoid to the pia mater along the posterior median sulcus of the cervical and upper thoracic parts of the spinal cord.
• pia mater : the innermost of the 3 meninges covering the brain and spinal cord, investing them closely and extending into the depths of the fissures and sulci; it consists of reticular, elastic, and collagenous fibers.
• pia mater cranialis or encephali : the pia mater covering the brain, very thin over the cerebral cortex, and thicker over the brain stem; the blood vessels for the brain ramify within it and, as they enter the brain, are accompanied for a short distance by a pial sheath
• pia mater spinalis : the pia mater covering the spinal cord and consisting of collagenous fibers, which also form the denticulate ligament, and reticular fibers, which closely invest the cord, form the various septa, and form an investment for the rootlets.
• pia-arachnoid squamous cell
Ontogenesis :
• Vignal's cells : embryonic connective tissue cells secreting myelin and associated with the formation of the axons of nerves in the fetus
• ventricular cell : any of the columnar epithelial cells of the neural tube.
• subpial periarterial space
• external glial limiting plate
Anatomy :
• encephalon / brain : that part of the CNS contained within the cranium, comprising the prosencephalon, mesencephalon, and rhombencephalon; it is derived (developed) from the anterior part of the embryonic neural tube. Any mature encephalon contains 10¹¹ neurons and 10¹⁵ synapses.
• neurocranium / brain box
• cartilaginous neurocranium / chondrocranium : formed by endochondral ossification and comprising the bones of the base of the skull (ethmoid and portions of the occipital, temporal, and sphenoid bones)
• Spöndel's foramen : a small transient foramen in the cartilaginous base of the developing skull between the ethmoid bone and the lesser wings of the sphenoid
• membranous neurocranium : formed by intramembranous ossification and comprising the bones of the calvaria (frontal and parietal and portions of the temporal, occipital, and sphenoid bones)
• emissary foramen : any foramen in a cranial bone that gives passage to an emissary vein
• sulci arteriosi / arterial sulci : grooves on the internal surfaces of the cranial bones for the meningeal arteries; called also arterial grooves.
• foveolae granulares / foveolae granulares [Pachioni] / granular foveolae : small pits on the internal surface of the cranial bones on either side of the sagittal sulcus; they are occupied by the arachnoidal granulations.
• sulcus sinus sagittalis superioris / sulcus for superior sagittal sinus / sagittal groove and sagittal sulcus : a groove on the internal surface of the frontal, parietal, and occipital bones that lodges the superior sagittal sinus
• sulcus sinus sigmoidei / sulcus for sigmoid sinus : an S-shaped sulcus beginning on the internal surface of the posteroinferior edge of the parietal bone and continuous with the lateral end of the sulcus of the transverse sinus; it passes onto the internal surface of the mastoid part of the temporal bone, where it bends inferiorly and medially to continue onto the lateral portion of the occipital bone, ending at the jugular foramen. It lodges the sigmoid sinus.
• sulcus sinus transversi / sulcus for transverse sinus / sulcus transversus ossis occipitalis : a wide groove that passes horizontally, lateralward, and anteriorly from the internal occipital protuberance to the parietal bone, where it becomes continuous with the sulcus of the sigmoid sinus; it lodges the transverse sinus
• sulci venosi / venous sulci / venous grooves : grooves on the internal surfaces of the cranial bones for the meningeal veins
• fossa cranii anterior / anterior cranial fossa / fossa cranialis anterior : the anterior subdivision of the floor of the cranial cavity, supporting the frontal lobes of the brain, and composed of portions of three bones: the ethmoid, frontal, and sphenoid
• fossa cranii media / middle cranial fossa / fossa cranialis media : the middle subdivision of the floor of the cranial cavity, supporting the temporal lobes of the brain and the pituitary gland; it is composed of the body and greater wings of the sphenoid bone and the squamous and petrous portions of the temporal bone
• fossa cranii posterior / posterior cranial fossa / fossa cranialis posterior : the posterior subdivision of the floor of the cranial cavity, lodging the cerebellum, pons, and medulla oblongata; it is formed by portions of the sphenoid, temporal, parietal, and occipital bones
• frontal bone (1) forms the forehead and the superior surface of the orbits.
• frontal sinus (air cavity that opens into the nasal cavity)
• coronal suture (joint between frontal and parietal bones).
• frontoethmoidal foramen : a foramen lying on the line of the frontoethmoidal suture.
• foramen caecum ossis frontalis / foramen cecum of frontal bone / cecal foramen : a blind opening formed between the frontal crest and the crista galli, which sometimes transmits a vein from the nasal cavity to the superior sagittal sinus
• supraorbital foramen / foramen supraorbitale : an opening in the frontal bone in the supraorbital margin, giving passage to the supraorbital artery and nerve; it is often present as a notch (incisura supraorbitalis) bridged only by fibrous tissue.
• tuber frontale / frontal tuber / eminentia frontalis / frontal eminence : one of the slight rounded prominences on the frontal bone on either side superior to the eyes, forming the most prominent portions of the forehead
• processus zygomaticus ossis frontalis / zygomatic process of frontal bone : a thick, strong process of the frontal bone, situated at the lateral end of the supraorbital margin and articulating with the zygomatic bone, and from which the temporal line starts.
• parietal bones (2) found on both sides of the skull, posterior to the frontal bone
• sagittal suture (joint between the 2 parietal bones).
• parietal foramen / foramen parietale : an opening on the posterior part of the superior portion of the parietal bone near the sagittal suture, for the passage of a vein and arteriole
• sulcus arteriae meningeae mediae / sulcus for middle meningeal artery : either of two grooves in the parietal bone for branches of the meningeal artery; one, posterior to the coronal suture, lodges the frontal branch, and the other, anterior to the mastoid angle, lodges the parietal branch.
• tuber parietale / parietal tuber / eminentia parietalis / parietal eminence: the somewhat laterally bulging prominence just superior to the superior temporal line on the external surface of the parietal bone
• sulcus sinus sigmoidei ossis parietalis / sulcus for sigmoid sinus of parietal bone / sulcus transversus ossis parietalis : a short groove on the internal surface of the posteroinferior angle of the parietal bone, continuous with both the sulcus for the sigmoid sinus on the temporal bone and the sulcus for the transverse sinus on the occipital bone; it lodges the superior part of the sigmoid sinus
• occipital bone (1) forms the posterior and inferior portions of the cranium.
• foramen magnum / foramen occipitale magnum / great occipital foramen : the large opening in the anterior and inferior part of the occipital bone, interconnecting the vertebral canal and the cranial cavity
• Kerckring's (Kerkring's) center or ossicle : an ossification center sometimes present in the posterior margin of the foramen magnum at about the sixteenth week of fetal life, which unites with the other squamous parts prior to birth
• condyles (oval projections on either side of foramen magnum that articulates with the atlas);
• lambdoidal suture (joint between occipital and parietal bones).
• sulcus sinus petrosi inferioris ossis occipitalis / sulcus for inferior petrosal sinus of occipital bone / sulcus petrosus inferior ossis occipitalis : the groove in the floor of the posterior cranial fossa at the line of junction between the basilar part of the occipital and the petrous portion of the temporal bone; it lodges the inferior petrosal sinus
• sulcus sinus sigmoidei ossis occipitalis / sulcus for sigmoid sinus of occipital bone : the portion of the sulcus of the sigmoid sinus found on the occipital bone.
• processus paramastoideus ossis occipitalis / paramastoid process of occipital bone : a process that in humans is represented by a tubercle on the inferior surface of the jugular process.
• eminentia cruciformis or cruciata / cruciate line / cruciform eminence of occipital bone : the cross-shaped bony prominence on the internal surface of the squama of the occipital bone, at the intersection of the ridges associated with the sulci of the superior sagittal sinus and the transverse sinuses
• temporal bones (2) are below the parietal bones, contributing to the sides and base of the cranium.
• squamosal suture (joint between temporal and parietal bone);
• external auditory meatus (the ear canal);
• processus mastoideus ossis temporalis / mastoid process of temporal bone : a conical process projecting forward and downward from the external surface of the petrous part of the temporal bone just posterior to the external acoustic meatus.
• mastoid sinus (air cavity that opens into the middle ear)
• Körner's septum : a bony plate sometimes found dividing the interior part of the mastoid into medial and lateral portions; it results from fusion of the squamous and petrous parts of the bone
• processus zygomaticus ossis temporalis / zygomatic process of temporal bone : a long, strong process arising from the inferior portion of the squamous part of the temporal bone, passing anteriorly from just superior to the entrance of the external acoustic meatus to join the zygomatic bone and thus forming the zygomatic arch. It has an anterior root and a posterior root extending along the temporal bone.
• mandibular fossa (oval depression anterior to the ear canal; articulates with mandible).
• tegmen tympani / roof of tympanum : the thin layer of translucent bone, on the petrous part of the temporal bone in the floor of the middle cranial fossa, separating the epitympanum from the cranial cavity
• pteriotic center : a center of ossification in the fetus and infant, from which are developed the tegmen tympani and the covering of the lateral semicircular canal.
• jugular foramen / foramen jugulare : the opening formed by the jugular notches on the temporal and occipital bones, for the transmission of various veins, arteries, and nerves
• mastoid foramen / foramen mastoideum : a prominent opening in the temporal bone posterior to the mastoid process and near its occipital articulation; an artery and vein usually pass through it
• stylomastoid foramen / foramen stylomastoideum : a foramen on the inferior part of the temporal bone between the styloid and mastoid processes, for the facial nerve and the stylomastoid artery
• sulcus arteriae occipitalis / sulcus for occipital artery / occipital groove : the groove just medial to the mastoid notch on the temporal bone, lodging the occipital artery
• sulcus arteriae temporalis mediae / sulcus for middle temporal artery : a nearly vertical groove running just superior to the external acoustic meatus on the external surface of the squamous part of the temporal bone; it lodges the middle temporal artery.
• sulcus canaliculi mastoidei : a small groove in the petrous portion of the temporal bone leading to the mastoid canaliculus.
• mallear sulcus of temporal bone / malleolar sulcus of temporal bone : a groove that runs obliquely downward and forward across the inner aspect of the anterior tympanic ring, which lodges the anterior process of the malleus, chorda tympani, and anterior tympanic artery at birth
• fissura petrooccipitalis / petrooccipital fissure / petrobasilar fissure : a fissure extending posteriorly from the foramen lacerum to the jugular foramen, between the basioccipital area and the posterior and inner border of the petrous portion of the temporal bone
• fissura petrosquamosa / petrosquamous fissure : a slight fissure of varying distinctness in the floor of the middle cranial fossa, marking the line of fusion between the squamous and petrous portions of the temporal bone
• fissura petrotympanica / petrotympanic fissure / glaserian fissure : a narrow transversely running slit just posterior to the articular surface of the mandibular fossa of the temporal bone; an arteriole and the chorda tympani nerve pass through it, and it lodges a portion of the malleus
• fissura tympanomastoidea / tympanomastoid fissure / petromastoid fissure : an external fissure on the inferior and lateral aspect of the skull between the tympanic portion and the mastoid process of the temporal bone; the auricular branch of the vagus nerve often passes through it
• fissura tympanosquamosa / tympanosquamous fissure / squamotympanic fissure : a line seen on the posterior wall of the external acoustic meatus at the junction between the tympanic and squamous parts of the temporal bone
• sulcus nervi petrosi majoris / sulcus for greater petrosal nerve / groove for greater petrosal nerve : a small groove sometimes present on the anterior surface of the petrous part of the temporal bone (the floor of the middle cranial fossa), running anteromedially from the hiatus of the facial canal to the foramen lacerum, and lodging the greater petrosal nerve; called also
• sulcus nervi petrosi minoris / sulcus for lesser petrosal nerve / groove for lesser petrosal nerve / innominate canaliculus / Arnold's canal : a small groove on the anterior surface of the petrous part of the temporal bone (the floor of the middle cranial fossa), running anteromedially just lateral to the sulcus of the greater petrosal nerve, and lodging the lesser petrosal nerve
• sulcus sinus petrosi inferioris ossis temporalis / sulcus for inferior petrosal sinus of temporal bone / sulcus petrosus inferior ossis temporalis : a groove on the posteromedial edge of the internal surface of the petrous portion of the temporal bone, which, with a corresponding groove on the adjacent basilar part of the occipital bone, lodges the inferior petrosal sinus
• sulcus sinus petrosi superioris / sulcus for superior petrosal sinus / sulcus petrosus superior ossis temporalis : a small posterolaterally directed sulcus that runs along the internal surface of the petrous part of the temporal bone on the angle separating the posterior and middle cranial fossae; it lodges the superior petrosal sinus
• sulcus sinus sigmoidei ossis temporalis / sulcus for sigmoid sinus of temporal bone / sulcus sigmoideus ossis temporalis : the portion of the sulcus of the sigmoid sinus found on the temporal bone
• sulcus tympanicus ossis temporalis / tympanic sulcus of temporal bone / Jacobson's sulcus : a narrow groove in the medial part of the external acoustic meatus of the temporal bone, into which the tympanic membrane fits; it is deficient above
• eminentia arcuata / arcuate eminence / eminence of superior semicircular canal : an arched prominence on the internal surface of the petrous part of the temporal bone in the floor of the middle cranial fossa, marking the position of the superior semicircular canal. It is particularly prominent in young skulls
• sphenoid bone (1) forms part of the floor of the cranium.
• greater wing (flat, lateral portion between the frontal and temporal bones)
• lingula of sphenoid / lingula sphenoidalis / sphenoidal lingula : a slender ridge of bone on the lateral margin of the carotid sulcus, projecting posteriorly between the body and greater wing of the sphenoid bone
• sphenotic center : a center of ossification in the fetal sphenoid bone for the lingula.
• sella turcica (central depression that encloses the pituitary gland)


• sphenoid sinus : air cavity that opens into the nasal cavity
• processus vaginalis ossis sphenoidalis / vaginal process of sphenoid bone : a small plate on the inferior surface of the body of the sphenoid bone on either side, running medially from the medial pterygoid plate to articulate with the ala of the vomer and with the sphenoid process of the palatine bone.
• processus clinoideus anterior / anterior clinoid process : the bony process found on the medial extremity of the posterior border of the lesser wing of the sphenoid bone.
• processus clinoideus medius / middle clinoid process : either of 2 small inconstant eminences on the internal surface of the sphenoid bone, one on either side of the anterior part of the hypophyseal fossa.
• processus clinoideus posterior / posterior clinoid process : either of 2 tubercles found on the superior angle of either side of the dorsum sellae of the sphenoid bone, and giving attachment to the tentorium of the cerebellum.
• processus pterygoideus ossis sphenoidalis / pterygoid process of sphenoid bone : either of two processes on the sphenoid bone descending from the points of junction of the greater wings and body of the bone, and each consisting of a lateral and a medial plate
• lamina lateralis processus pterygoidei / lateral lamina of pterygoid process / lateral pterygoid plate : either of a pair of bony plates projecting downward from the roots of the greater wings of the sphenoid bone and forming the medial wall of the ipsilateral infratemporal fossa
• processus pterygospinosus / processus pterygospinosus [Civinini] / pterygospinous process : a small spine on the posterior edge of the lateral pterygoid plate of the sphenoid bone, giving attachment to the pterygospinous ligament.
• caroticoclinoid foramen : the foramen between the anterior and middle clinoid processes in the minority of sphenoid bones where those processes meet at their outer ends.
• foramen diaphragmatis [sellae] : the opening in the center of the diaphragm of the sella through which the infundibulum passes.
• foramen lacerum : an irregular gap formed at the junction of the base of the greater wing of the sphenoid bone, the tip of the petrous part of the temporal bone, and the basilar part of the occipital bone; in life, it does not exist, being occupied by an unossified part of the petrous part of the temporal bone
• foramen ovale ossis sphenoidalis / foramen ovale of sphenoid : an opening in the posterior part of the medial portion of the greater wing of the sphenoid bone; it transmits the mandibular branch of the trigeminal nerve and some vessels.
• foramen rotundum ossis sphenoidalis / round foramen of sphenoid bone / superior maxillary foramen or canal : a round opening in the medial part of the greater wing of the sphenoid bone that transmits the maxillary branch of the trigeminal nerve
• foramen petrosum / petrosal foramen : a small opening sometimes present posterior to the oval foramen for transmission of the lesser petrosal nerve; called also canaliculus innominatus and innominate canaliculus
• foramen sphenopalatinum / sphenopalatine foramen / pterygopalatine foramen : an opening on the medial wall of the pterygopalatine fossa, interconnecting this fossa with the nasal cavity, and transmitting the sphenopalatine artery and nasal nerves
• foramen spinosum / spinous foramen : an opening in the greater wing of the sphenoid bone, near its posterior angle, for the middle meningeal artery.
• clivus blumenbachii / Blumenbach's clivus : a bony surface in the posterior cranial fossa, sloping superiorly from the foramen magnum to the dorsum sellae
• clivus ossis occipitalis / basilar clivus / clivus basilaris / basilar groove of occipital bone : the lower part of the clivus, formed by the basilar portion of the occipital bone
• clivus ossis sphenoidalis / basilar groove of sphenoid bone : the upper part of the clivus, formed by a surface of the body of the sphenoid bone
• sulcus caroticus ossis sphenoidalis / carotid sulcus : the groove on the side of the body of the sphenoid bone that lodges the internal carotid artery and the cavernous sinus.
• fissura orbitalis inferior / inferior orbital fissure : a cleft in the inferolateral wall of the orbit bounded by the great wing of the sphenoid and the orbital process of the maxilla; it transmits the infraorbital and zygomatic nerves and the infraorbital vessels
• fissura orbitalis superior / superior orbital fissure : an elongated cleft between the small and great wings of the sphenoid bone, which transmits various nerves and vessels.
• fissura pterygomaxillaris / pterygomaxillary fissure / pterygopalatine fissure : a cleft just posterior to the inferior orbital fissure between the lateral pterygoid plate and the maxilla
• fissura spheno-occipitalis / sphenooccipital fissure / basilar or occipitosphenoidal fissure : the fissure between the basilar part of the occipital bone and the body of the sphenoid bone
• fissura sphenopetrosa / sphenopetrosal fissure / angular or petrosphenoidal fissure : a fissure in the floor of the middle cranial fossa between the posterior edge of the greater wing of the sphenoid bone and the petrous part of the temporal bone
• sulcus hamuli pterygoidei / sulcus of pterygoid hamulus : a smooth groove on the lateral surface of the medial pterygoid plate of the sphenoid bone, in the angle at the base of the pterygoid hamulus; it lodges the tendon of the tensor veli palatini muscle.
• palatinovaginal sulcus / sulcus palatinovaginalis : the groove on the vaginal process of the pterygoid process of the sphenoid bone that participates in formation of the palatinovaginal canal.
• prechiasmatic sulcus / sulcus prechiasmaticus / sulcus prechiasmatis / chiasmatic sulcus / sulcus chiasmatis / optic groove / optic sulcus : a furrow on the superior surface of the sphenoid bone, located just anterior to the tuberculum sellae; it lodges the optic chiasm
• sulcus pterygopalatinus processus pterygoidei / pterygopalatine sulcus of pterygoid process : a small groove on the inferior surface of the vaginal process of the medial pterygoid plate of the sphenoid bone, forming part of the wall of the vomerovaginal canal.
• sulcus tubae auditoriae / sulcus for auditory tube / sulcus tubae auditivae / groove for auditory tube : a groove on the medial part of the base of the spine of the sphenoid bone; it lodges a portion of the cartilaginous part of the auditory tube
• vomerovaginal sulcus / sulcus vomerovaginalis : the groove on the vaginal process of the pterygoid process of the sphenoid bone that helps form the vomerovaginal canal
• rostrum sphenoidale / sphenoidal rostrum : the prominent ridge on the inferior surface of the sphenoid bone that articulates with a deep depression between the wings of the vomer.
• ethmoid bone (1) found anterior to the sphenoid bone, consisting of two honeycombed masses of bone.
• hiatus semilunaris / semilunar hiatus : the deep semilunar groove anterior and inferior to the bulla of the ethmoid bone; the anterior ethmoidal (air) cells, the maxillary sinus, and sometimes the frontonasal duct drain through it via the ethmoid infundibulum
• ethmoid sinus : air cavity that opens into nasal cavity
• lamina cribrosa ossis ethmoidalis / cribriform lamina or plate of ethmoid bone : the horizontal plate of the ethmoid bone that forms the roof of the nasal cavity; it is perforated by many foramina (foramina cribrosa ossis ethmoidalis) for the passage of the olfactory nerves. On its superior surface is a projection for attachment of meninges called the crista galli
• olfactory foramina : on either side of base of crista galli; olfactory nerves pass through foramina
• perpendicular plate : upper part of nasal septum
• conchae : 4 are part of ethmoid and 2 inferior are separate bones (shelf-like projections into nasal cavities, which increase surface area of nasal mucosa
• foramen ethmoidale anterius / anterior ethmoidal canal or foramen / anterior internal orbital canal : the anterior of two small grooves found as a pair crossing the superior surface on both sides of the ethmoid labyrinth, at its junction with the roof of each orbit; it transmits the nasal branch of the ophthalmic nerve and the anterior ethmoid artery and vein
• foramen ethmoidale posterius / posterior ethmoidal canalor foramen / posterior internal orbital canal : the posterior of two small grooves found as a pair crossing the superior surface on both sides of the ethmoid labyrinth, at its junction with the roof of each orbit; it transmits the posterior ethmoid artery and vein





• suturae craniales or cranii / cranial sutures : the sutures (a type of fibrous joint in which the apposed bony surfaces are so closely united by a thin layer of fibrous connective tissue that no movement can occur; found only in the skull) between the various bones of the skull, named generally for the specific components participating in their formation. They are all ossified after age 50.
• sutura coronalis / arcuate or coronal suture : the line of junction of the frontal bone with the two parietal bones.
• sutura ethmoidolacrimalis / ethmoidolacrimal or lacrimoethmoidal suture : the vertical line of junction, on the medial wall of the orbit, between the lacrimal bone and the orbital plate of the ethmoid bone
• sutura ethmoidomaxillaris / ethmoidomaxillary suture : the line of junction between the orbital lamina of the ethmoid bone and the orbital surface of the maxilla.
• sutura frontalis / frontal suture : the usually transient line of junction between the right and left halves of the frontal bone. The inferior part may persist in the adult, in which case it is called the metopic suture / sutura frontalis metopica or persistens
• sutura frontoethmoidalis / frontoethmoidal suture : the line of junction in the anterior cranial fossa between the frontal bone and the cribriform plate of the ethmoid bone.
• sutura frontolacrimalis / frontolacrimal suture : the line of junction between the upper edge of the lacrimal bone and the orbital part of the frontal bone.
• sutura frontomaxillaris / frontomaxillary suture : the line of junction between the frontal bone and the frontal process of the maxilla.
• sutura frontonasalis / frontonasal or nasofrontal suture : the line of junction between the frontal and the two nasal bones
• sutura frontozygomatica / frontozygomatic or zygomaticofrontal suture : the line of junction between the zygomatic bone and the zygomatic process of the frontal bone
• sutura incisiva / incisive or premaxillary suture / suture of Goethe : an indistinct suture sometimes seen extending laterally from the incisive fossa to the space between the canine tooth and the lateral incisor, indicating the line of fusion between the premaxilla and the maxilla.
• sutura intermaxillaris / intermaxillary suture : the line of junction between the maxillary bones of either side, just inferior to the anterior nasal spine.
• sutura internasalis / internasal suture : the line of junction between the two nasal bones.
• sutura lacrimoconchalis / lacrimoconchal suture : the line of junction between the lacrimal bone and the inferior nasal concha.
• sutura lacrimomaxillaris / lacrimomaxillary suture : a suture on the inner wall of the orbit, between the lacrimal bone and the maxilla.
• sutura lambdoidea / lambdoid suture : the line of junction between the occipital and parietal bones, shaped like the Greek letter lambda.
• sutura occipitomastoidea / occipitomastoid suture : an extension of the lambdoid suture between the occipital bone and the posterior edge of the mastoid portion of the temporal bone.
• sutura nasomaxillaris / nasomaxillary suture : the line of junction between the lateral edge of the nasal bone and the frontal process of the maxilla.
• sutura palatina mediana / median palatine suture : the line of junction between the horizontal part of the palatine bones of either side.
• sutura palatina transversa / transverse palatine suture : the line of junction between the palatine processes of the maxillae and the horizontal parts of the palatine bones.
• sutura palatoethmoidalis / palatoethmoidal suture : the line of junction between the orbital process of the palatine bone and the orbital lamina of the ethmoid bone.
• sutura palatomaxillaris / palatomaxillary suture : the suture in the floor of the orbit, between the orbital processes of the palatine bone and the orbital portion of the maxilla.
• sutura parietomastoidea / parietomastoid or bregmatomastoid suture : the line of junction between the posterior inferior angle of the parietal bone and the mastoid process of the temporal bone.
• sutura sagittalis / biparietal, rhabdoid or sagittal suture : the line of junction between the 2 parietal bones.
• sutura dentata or serrata / serrated suture : a type of suture in which the participating bones are united by interlocking processes resembling the teeth of a saw.
• sutura sphenoethmoidalis / sphenoethmoidal suture : the line of junction between the body of the sphenoid bone and the orbital lamina of the ethmoid bone.
• sphenoethmoidal (SE) suture or point : a craniometric landmark, being the most superior point of the sutura sphenoethmoidalis
• sutura sphenofrontalis / sphenofrontal suture : a long suture joining the orbital part of the frontal bone to the greater and lesser wings of the sphenoid bone on either side of the skull.
• sutura sphenomaxillaris / sphenomaxillary suture : a suture occasionally seen between the pterygoid process of the sphenoid bone and the maxilla.
• sutura sphenoorbitalis / sphenoorbital suture : the line or junction between the orbital process of the palatine bone and the body of the sphenoid bone.
• sutura sphenoparietalis / sphenoparietal suture : the line of junction between the greater wing of the sphenoid bone and the parietal bone.
• sutura sphenosquamosa / sphenosquamous suture : the line of junction between the greater wing of the sphenoid bone and the squamous part of the temporal bone.
• sutura sphenovomeralis or sphenovomeriana / sphenovomerine suture : the line of junction between the vaginal processes of the medial pterygoid plates of the sphenoid and the ala of the vomer.
• sutura sphenozygomatica / sphenozygomatic suture : the line of junction between the greater wing of the sphenoid bone and the zygomatic bone.
• sutura squamomastoidea or squamosomastoidea / squamomastoid suture : a suture existing early in life between the squamous and mastoid portions of the temporal bone
• sutura squamosa cranii / squamous suture of cranium : the sutura squamosa / squamous suture (a type of suture formed by overlapping of the broad beveled edges of the participating bones( between the squamous part of the temporal bone and the parietal bone.
• sutura temporozygomatica / temporozygomatic suture : the line of junction between the zygomatic process of the temporal bone and the temporal process of the zygomatic bone.
• sutura infraorbitalis or zygomaticomaxillaris / zygomaticomaxillary suture : the line of junction between the zygomatic bone and the zygomatic process of the maxilla.
• fissura petrooccipitalis / petrobasilar or petrooccipital fissure / petrosphenooccipital suture of Gruber : a fissure extending posteriorly from the foramen lacerum to the jugular foramen, between the basioccipital area and the posterior and inner border of the petrous portion of the temporal bone
• fissura petrosquamosa / petrosquamous fissure : a slight fissure of varying distinctness in the floor of the middle cranial fossa, marking the line of fusion between the squamous and petrous portions of the temporal bone.
• fissura sphenopetrosa / sphenopetrosal, angular or petrosphenoidal fissure : a fissure in the floor of the middle cranial fossa between the posterior edge of the greater wing of the sphenoid bone and the petrous part of the temporal bone
• fissura spheno-occipitalis / sphenooccipital fissure / basilar or occipitosphenoidal fissure or suture : the fissure between the basilar part of the occipital bone and the body of the sphenoid bone
• synchondroses craniales / synchondroses cranii / synchondroses of skull / cranial synchondroses : the cartilaginous junctions between certain bones of the cranium
• synchondrosis intersphenoidalis / intersphenoidal synchondrosis : the cartilaginous union of the two halves of the body of the sphenoid bone in the fetus
• synchondrosis intraoccipitalis anterior / anterior intraoccipital synchondrosis : the cartilaginous union of the pars basilaris with the partes laterales of the occipital bone in the newborn
• synchondrosis intraoccipitalis posterior / posterior intraoccipital synchondrosis : the cartilaginous union of the squama with the partes laterales of the occipital bone in the newborn
• synchondrosis petrooccipitalis / petrooccipital synchondrosis / petrobasilar suture / petrosphenobasilar suture / sphenopetrosal suture : the plate of cartilage in the petrooccipital fissure which helps to unite the basilar portion of the occipital bone and the petrous portion of the temporal bone
• synchondrosis sphenoethmoidalis / sphenoethmoidal synchondrosis : the cartilaginous union between the body of the sphenoid and the labyrinth of the ethmoid bone.
• synchondrosis sphenooccipitalis / sphenooccipital synchondrosis : the cartilaginous union of the anterior end of the basilar portion of the occipital bone with the posterior surface of the body of the sphenoid bone.
• sphenooccipital (SO) synchondrosis : in cephalometric radiology, the uppermost point of the synchondrosis sphenooccipitalis
• synchondrosis sphenopetrosa / sphenopetrosal synchondrosis : the cartilaginous union of the inferior border of the greater wing of the sphenoid bone with the petrous portion of the temporal bone in the sphenopetrosal fissure
• fonticuli cranii / cranial fontanelles : the membrane-covered spaces, or soft spots, remaining at the incomplete angles of the parietal and adjacent bones, until ossification of the skull is completed
• fonticulus anterior or frontalis [major] / anterior, bregmatic or frontal fontanelle : situated at the junction of the frontal, coronal, and sagittal sutures. It ossifies between month 18 and 24 of extrauterine life
• fonticulus occipitalis, posterior or minor / lambdoid, occipital, posterior or triangular fontanelle : at the junction of the sagittal and lambdoidal sutures. It ossifies at month 3 of extrauterine life
• lateral fontanelles
• fonticulus sphenoidalis or anterolateralis / anterolateral or sphenoidal fontanelle : at the junction of the parietal and frontal bones, the greater wing of the sphenoidal, and the squamous part of the temporal bones
• fonticulus mastoideus or posterolateralis / posterolateral, posterotemporal or mastoid fontanelle / Casser's, casserian or Casserio's fontanelle : at the junction of the lambdoidal, parietomastoid, and occipitomastoid sutures
• Gerdy's or sagittal fontanelle : a fontanelle occasionally occurring in the sagittal suture
• cerebrum : the main portion of the brain, occupying the upper part of the cranial cavity; its 2 hemispheres, united by the corpus callosum, form the largest part of the CNS in man. It is derived (developed) from the telencephalon of the embryo. In official nomenclature, the term is considered an alternative to telencephalon
• hemispherium cerebri / cerebral hemisphere / hemispherium cerebralis : either of the pair of structures, formed by evagination of the embryonic telencephalon, lying on either side of the midline, partly separated by the longitudinal cerebral fissure, containing a central cavity, the lateral ventricle, and covered by a layer of gray substance, the cerebral cortex; together they constitute the largest part of the brain in humans.
• fissura longitudinalis cerebralis or cerebri / longitudinal cerebral fissure : the deep fissure between the cerebral hemispheres extending inferiorly to the corpus callosum.
• cortex cerebri or cerebralis / cortex of cerebrum / cerebral cortex / pallium : the thin (about 3 mm) layer or mantle of gray substance covering the surface of each cerebral hemisphere, folded into gyri that are separated by sulci. It is responsible for the higher mental functions, for general movement, for visceral functions, perception, and behavioral reactions, and for the association and integration of these functions

Classification based on phylogenetic and ontogenetic differences :
• isocortex / neocortex / homotypical or nonolfactory cortex / neopallium : the newer, 6-layered portion of the cerebral cortex, showing stratification and organization characteristic of the most highly evolved type of cerebral tissue
• molecular layer / lamina I
• stria laminae molecularis or plexiformis / stria of molecular layer : a band of tangentially oriented myelinated nerve fibers
• external granular layer / lamina granularis externa : layer II of the cerebral cortex, composed of many small pyramidal cells and granule cells with short axons
• stria laminae granularis externae / stria of external granular layer : a band of tangentially oriented nerve fibers
• external pyramidal layer / lamina III
• lamina granularis interna / internal granular layer : layer IV of the cerebral cortex, composed of many densely packed granule cells with short axons and some small pyramidal cells; it contains neurites derived from cells of other layers and areas of the cerebral cortex and subcortical areas.
• stria laminae granularis internae / stria of internal granular layer / external band, line, stria / stripe of Baillarger : a band of tangentially oriented white nerve fibers in the internal granular layer of the cerebral cortex. In the region of the calcarine sulcus, this stria is thick and highly visible and here is known as the line or stria of Gennari
• internal pyramidal layer / lamina V
• stria laminae pyramidalis internae / stria of internal pyramidal layer / internal band, line, stria, or stripe of Baillarger : a band of tangentially oriented white nerve fibers
• pyramidal cell / pyramidal neuron : one of the large multipolar pyramid-shaped cells of the cerebral cortex, having a single apical dendrite extending outward toward the surface and several dendrites extending inward; a few are inverted so that their apical dendrites extend inward. They vary in size from :
• small
• Betz's cells / giant pyramidal cells : large pyramidal ganglion cells
• multiform layer / lamina VI
• Martinotti's cells : fusiform cells with ascending axon processes in the layers of the cerebral cortex, especially in the multiform layer and also in the internal pyramidal layer
• agranular cortex : a type of cortex occurring in some parts of the neocortex, having very thin granular layers; seen in the motor area of the precentral gyrus and elsewhere.
• allocortex / heterotypical cortex : the older, original part of the cerebral cortex that does not have the 6-layered histologic structure of the larger, phylogenetically newer isocortex; it  develops in association with the olfactory system
• archicortex / archaeocortex / archeocortex / archipallium / olfactory cortex : the embryonic archaeocortex corresponds to the cortex of the dentate gyrus and hippocampus in mature mammals
• rhinocoele / rhinocele : the ventricle of the olfactory lobe of the brain.
• paleocortex / palaeocortex : it is composed chiefly of the piriform cortex and the parahippocampal gyrus

• differences in overall brain size : the size of mammalian brains can vary a great deal, in both overall and relative terms. At a given body weight, brain weight can vary > 5-fold across species140. For example, squirrel monkeys (Saimiri spp) weigh about 680 g, galagos (Galago spp) about 850 g and hedgehogs (Erinaceus spp) roughly 860 g. Although individuals of these species weigh roughly the same, their brain weights differ vastly: 22.0 g, 10.3 g and 3.4 g, respectively141.
• differences in the number of cortical areas : all mammals seem to have about 20 common cortical areas, but the number of areas has increased along certain branches of mammalian evolution. Rhesus monkeys and other primates, for instance, have more visual, somatosensory and prefrontal areas than rats, hedgehogs or opossums. The Primate order might have unique cortical areas, such as the middle temporal visual area, that are not homologous to cortical areas in non-primates.
• variation in connectivity between brain areas : although certain brain areas are common to mammalian species, their connectivity patterns vary considerably. For example, in cats, the lateral geniculate nucleus (LGN) projects to visual areas 17 (the primary visual cortex, V1) and 18 (V2). However, in primates, the LGN projects almost exclusively to V1; the main input to V2 is from V1. A similar shift from parallel thalamocortical projections to a serial processing pattern has occurred in the primate somatosensory system.
• variation in cellular organization : comparative studies have revealed that the cellular structure of the cortical areas of different species can differ markedly. For example, relative to neighbouring pyramidal neurons in V1, Meynert cells are much larger in patas monkeys (Erythrocebus patas) and baboons (Papio spp.) than in humans and other primates. By contrast, human Betz cells are much larger relative to neighbouring pyramidal neurons than those of other primates. Some cell types and laminar patterns seem to be unique to apes (including humans). The large ‘spindle cells’ of the cingulate cortex are found only in apes. Perhaps most surprising (given how often the macaque visual system is assumed to exactly replicate the human visual system) is that the primary visual cortex of Old and New World monkeys contains a dense cytochrome oxidase-containing band in layer 4A that is not evident in great apes (including humans)
The human left and right cerebral hemispheres are anatomically and functionally asymmetric. To test whether human cortical asymmetry has a molecular basis, gene expression levels between the left and right embryonic hemispheres were studied using Serial Analysis of Gene Expression (SAGE), and 27 differentially expressed genes were identified and verified, suggesting that human cortical asymmetry is accompanied by early, striking transcriptional asymmetries. LMO4 is consistently more highly expressed in the right perisylvian human cerebral cortex than in the left, and is essential for cortical development in mice, suggesting that human left-right specialization reflects asymmetric cortical development at early stages^ref.
Classification into cortical areas : any portion of the cerebral cortex that can be differentiated functionally from its neighbors
• field
• zone
• Brodmann's areas : areas of the cerebral cortex distinguished by hypothesized differences in the arrangement of their 6 cellular layers and identified by numbers; although the histologic basis is in dispute, the topographic numbering is widely used as a descriptor for mapping cortical locations that control different functions of the nervous system and the body



• primary areas : areas of the cerebral cortex comprising the motor and sensory regions
• sensorimotor area : the cortex of the Brodmann's area 4 / precentral gyrus and postcentral gyrus—the motor area and the primary receptive area for general sensations, respectively.
• primary receiving or receptive areas : the areas of the cerebral cortex that receive the thalamic projections of the primary sensory modalities.
• projection areas : those areas of the cerebral cortex that receive the most direct projection of the sensory systems of the body.
• postcentral or postrolandic area / somesthetic cortex : the sensory area in postcentral gyrus, the primary receptive area for general sensations. The so-called homunculus sensitivus :


• somatic sensory or somatosensory area : either of the 2 cortical regions where conscious perception of somatic sensations occurs
• first or primary somatosensory area (SI area) : the cortical projection area in the postcentral gyrus for receiving into consciousness somatosensory information initiated by stimulation of receptors in the skin, joints, muscles, and viscera
• second or secondary somatosensory area (SII area) : a cortical projection area lateral and posterior to the primary somatosensory area; it receives somatic sensations mainly from the skin, particularly sensations of pain and of movement across the skin
• auditory (receiving) areas : 2 contiguous areas of the temporal lobe in the region of the anterior transverse temporal gyrus (Brodmann's areas 41 and 42); designated AI (first or primary auditory area) and AII (second or secondary auditory area). Auditory imagery occurs when one mentally rehearses telephone numbers or has a song 'on the brain' — it is the subjective experience of hearing in the absence of auditory stimulation, and is useful for investigating aspects of human cognition. Auditory and visual imagery seem to obey similar basic neural principles : sound of silence activates auditory cortex^ref. The discovery of a group of pitch-sensitive cells in the brain has sent reverberations through the field of music perception. Researchers think that studying these neurons will reveal how our minds grasp songs and speech. Most people can hear that 2 instruments are playing the same note, even if they sound as different as a trumpet and a piano. Our perception of fundamental sound frequency or 'pitch' remains constant despite differences in an instrument's acoustical traits. This holds true even when the fundamental frequency is actually missing from a complex sound. If several strings are plucked such that they vibrate at their higher harmonics, at 800, 1,000 and 1,200 hertz for example, we will perceive the sound as belonging to the same pitch as the primary harmonic of those strings: 200 hertz. For centuries scholars have puzzled over how the brain does this. In recent years, researchers have looked at the role played by the primary auditory cortex, the brain region known to digest sounds. Human brain scans have indicated that a peripheral bit of this brain region is active when we try to identify pitch. But no one could find cells that responded to specific frequencies, leaving it a mystery how we interpret them. A study with marmoset monkeys (Callithrix jacchus) has now shown up specific neurons that do just that. This is the first evidence that there are individual neurons in the brain that are encoding for pitch. The neurons were identified by recording the response of the monkeys' brain cells while the animals heard various notes from a computer. Individual cells consistently got excited by sounds at specific frequencies, or multiples of that frequency. Just as humans can perceive a pitch even if the fundamental is missing, the monkeys' neurons for 200 hertz lit up when presented with a mix of 800-, 1,000- and 1,200-hertz sounds. Exactly how a given frequency sets off a single cell remains unclear. But experts say the location of this unique population of neurons is an important first step. The discovery will open doors for investigators to explore how other primates, including humans, appreciate music. There are about a thousand studies one can think of doing after this^ref
• striate cortex or area / first visual area : Brodmann's area 17: the part of the occipital lobe of the cerebral cortex that receives the fibers of the optic radiation from the lateral geniculate body and is the primary receptive area for vision; so called because of the prominent broad line or stria of Gennari
• motor area : any area of the cerebral cortex primarily involved in stimulating muscle contractions; often used alone to refer to the primary somatomotor area
• primary somatomotor area / Betz cell area / motor area / precentral area / rolandic area / Rolando's zone : an area in the posterior part of the frontal lobe just anterior to the central sulcus, corresponding to Brodmann's area 4 / precentral gyrus ; different regions control motor activity of specific parts of the body, composing the so-called homunculus motorius.


• suppressor areas : cortical areas whose activation is thought to suppress or prevent movement
• strip area : a strip of cortex between the motor and premotor areas thought to be suppressor in function.
• premotor area / eupraxic center : the motor cortex of the frontal lobe immediately in front of the precentral gyrus.
• supplementary motor area : an area in the gyrus frontalis medius just above the gyrus cinguli and anterior to the part of the first somatomotor area that mediates movements of the lower extremity.
• motor speech areas
• Broca's motor speech area / glossokinesthetic center : an area comprising parts of the opercular portion of the inferior frontal gyrus
• Wernicke's second motor speech area, field or zone / auditory word center : originally a term denoting a speech center thought to be confined to the posterior part of the superior temporal gyrus adjacent to the transverse temporal gyri; the term now includes a wider zone that encompasses the supramarginal and angular gyri as well
• supplementary areas : small motor and sensory areas of the cerebral cortex in addition to the primary areas.
• association areas : areas of the cerebral cortex (excluding the primary areas) that are connected with each other and with the neothalamus by numerous fibers passing through the corpus callosum and the white matter of the hemispheres; these areas are responsible for the higher mental and emotional processes, such as memory, learning, speech, and the interpretation of sensations.
• sensory association area : an association area around the borders of a primary receptive area, where sensory stimuli are interpreted.
• auditory association area / auditopsychic center : for auditory stimuli
• visual association areas : areas of the occipital cortex partly surrounding the striate cortex
• parastriate area : Brodmann's area 18
• peristriate area : Brodmann's area 19
• prefrontal area : the cortex of the frontal lobe immediately in front of the premotor cortex, concerned chiefly with associative functions
• visual cortex : the area of the occipital lobe of the cerebral cortex concerned with vision; it consists of
• first visual area or striate cortex
• visual association areas
• handedness : the preferential use in voluntary motor acts of the hand of one side.
• left handedness : the preferential use in voluntary motor acts of the left hand. Left-handed people thrive best in the most murderous societies, according to a study of 8 tribes across the world. The discovery may help to answer the riddle of why a minority of left-handers persist in human populations. Being a southpaw is an advantage in a host of confrontational situations. Lefties are far more common at the top of sports such as boxing and fencing than in normal society. The benefit comes from the element of surprise: most opponents will be less used to facing a left-handed adversary. But stress during development or birth may divert the nervous system from its default, right-handed path. And developmental stress is also linked to reduced lifespan, low birthweight and increased incidence of immune and nervous disorders, meaning that natural selection might be expected to weed out lefties altogether. So might this combination of cost and benefit be what keeps left-handedness at its constant yet low level in the population? Among the Jula (Dioula) people of Burkina Faso, the most peaceful tribe studied, where the murder rate is 1 in 100,000 annually, left-handers make up 3.4% of the population. But in the Yanomami tribe of Venezuela, where more than 5 in 1,000 meet a violent end each year, southpaws account for 22.6%^ref. Many of the data rely on interviews with elder tribespeople, who may not report sensitive events truthfully or may have trouble recalling them. What's more, they only take account of fights that went right to the death. Nonetheless, the relationship between murder rate and handedness is very clear, despite the study's inaccuracies. This shows that left-handers really do benefit from their surprising style in hand-to-hand fights. The picture is more complex in Western societies, where left-handedness hovers around the 10% mark. Although hardly free from one-on-one violence, the advent of long-range weapons such as guns and bombs complicates the picture. But the pattern seen in the tribes matches that seen in the ritualized confrontations of Western sport. And left-handers enjoy the greatest success in those sports that are fought at closest quarters. The frequency of left-handers is much higher in sports. And in boxing and fencing it's higher than in tennis, where you're further away from each other. It's not at all seen in solo sports such as gymnastics: here left-handers are in the same proportion as in the general population.
• right handedness : the preferential use in voluntary motor acts of the right hand
• language area : any center of the cortex, usually in the dominant hemisphere (right hemisphere in right-handed and 90% of left-handed people), controlling the understanding or use of spoken and written language.
• primary or perisylvian language areas (joined by fasciculus arciformis). They undergo maturation as first and mediate the correct selection and rapid combination of phonems) and repetition of heard words (via the fasciculus arciformis)
• Brodmann's area 44 / Broca's  motor speech area
• Brodmann's area 28 / Wenicke's area
• secondary, marginal or accessory language areas. They undergo maturation since age 2 and mediate the correct selection and combination of words into phrases
• premotor area
• prefrontal area
• temporoparietooccipital areas (Brodmann's areas 37 and 39)
• olfactory area : a general area, including the olfactory bulb, tract, and trigone, the anterior portion of the gyrus cinguli, and the uncus
• piriform area or lobe : an area in the rhinencephalon, pear-shaped in some species but not in humans; it includes the lateral olfactory process or gyrus, the limen insulae, the uncus, and part of the parahippocampal gyrus; subdivided into
• periamygdaloid area : the intermediate part of the piriform area, between the piriform area and the entorhinal area; it covers the amygdala
• entorhinal area : Brodmann's area 28, the inferior and posterior parts of the piriform area, including the caudal part of the parahippocampal gyrus
• alvear fasciculus or path : a bundle of fibers that originates in the medial part of the entorhinal area and extends to the alveus of the hippocampus, where it has synapses with fibers that go to the dentate gyrus
• prepiriform area : the anterior part of the piriform area, consisting primarily of the lateral olfactory gyrus
• piriform cortex : the cortex of the piriform lobe or area. Some animals can recognize that a meal is deficient in amino acids, and thus reject such offerings within 20 minutes. This behavioral response to amino acid deficiency in omnivores has been known for some time, but the nutrient sensor has eluded discovery. The biochemical pathway that senses amino acid deficiencies in yeast is also at work in mammals. In yeast, a deficiency of a particular amino acid causes an accumulation of that amino acid's corresponding uncharged tRNA, which activates the kinase GC nonderepressing 2 (GCN2) / EIF2AK4, which then phosphorylates eIF-2a. This signal decreases the yeast's global protein synthesis and increases transcription of genes that synthesize deficient amino acids. In rats it alters eating behavior via the neurons of the anterior piriform cortex. Rats will normally spend 30-45 minutes eating, if they haven't eaten for a while before that. Beginning at about 20 minutes, researchers have shown that rats eating food deficient in essential amino acids will eat less than those eating normal food^ref. When tRNA charging by tRNA synthetases in rats is inhibited by injecting amino alcohols—alcohol derivatives of amino acids—into the anterior piriform cortex, a brain region that projects to feeding circuits and has long been known to sense amino acid deficiencies^ref, the same pathway as in yeasts is activated. About 20 minutes after receiving injections of the amino alcohol L-threoninol, the rats began to eat less food than normal, as if they were eating food with no threonine, Gietzen said. After injections of L-leucinol, they also ate less than control rats. Injections of alcohol derivatives of the dispensable amino acids serine and proline, however, did not affect the rats' feeding. Also, the stereoisomer D-threoninol did not change their food intake, presumably because it doesn't interfere with charging of mammalian amino acids, which are all L isomers. This amino acid chemosensory brain area projects to neural circuits controlling food intake^ref.
• circumventricular organs (CVO) : several small structures located around the edges of the third and fourth ventricles, lacking the regular blood-brain barrier (BBB) and thus serving as significant sites for neural-endocrine interaction. They include the
• area postrema : a small tongue-shaped area on the lateral wall of the fourth ventricle, between the funiculus separans and the tuberculum gracile, in which the blood-brain barrier (BBB) may be modified
• chemoreceptor trigger zone (CTZ) : part of the area postrema in the fourth ventricle that mediates physiological reactions to various chemicals and drugs and plays an indirect role in stimulation of vomiting. It mediates some impulses that in turn stimulate the vomiting center in the medulla oblongata
• median eminence : the raised area on the infundibulum hypothalami at the floor of the third ventricle of the brain. Continuous below with the infundibular stem or stalk of the pituitary gland, it contains the primary capillary network of the hypophysial portal system. In some anatomical classification systems it is included as part of the neurohypophysis and in others as part of the tuber cinereum
• organum subcommissurale / subcommissural organ : a group of tall columnar ciliated ependymal cells lining the dorsal aspect of the cerebral aqueduct, situated dorsoventral to the commissure of the epithalamus; it is one of the circumventricular organs and may have neuroendocrine and neurosecretory functions.
• organum subfornicale / subfornical organ / intercolumnar tubercle : a group of specialized ependymal cells, similar to those of the subcommissural organ, projecting toward the cavity of the third ventricle from its anterior wall between the columns of the fornix. It is stimulated by angiotensin II
• organum vasculosum of lamina terminalis (OVLT) : an area of the lamina terminalis hypothalami where many neurons pass through a double-layered capillary bed and the blood-brain barrier (BBB) is modified; it has a superficial capillary layer that receives blood from nearby arteries and drains into a deeper layer, from which blood passes to the cerebral veins.
Sometimes also included are :
• funiculus separans : a narrow translucent ridge of thickened ependyma in the floor of the fourth ventricle that runs across the lower part of the trigone of the vagus nerve and separates it from the area postrema; the blood-brain barrier may be modified in this area
• neurohypophysis
• pineal body
• septal area : the area on either cerebral hemisphere comprising the area subcallosa and the corresponding half of the septum pellucidum; the area has olfactory, hypothalamic, and hippocampal connections
• area subcallosa / subcallosal area : a small area of cortex on the medial surface of each cerebral hemisphere, between the anterior and posterior parolfactory sulci..
Other cell types :
• Meynert's cells / solitary cells of Meynert : large solitary pyramidal cells in the cerebral cortex, found in a single row near the calcarine fissure
• pyramidal cell or neuron : one of the large multipolar pyramid-shaped cells of the cerebral cortex, having a single apical dendrite extending outward toward the surface and several dendrites extending inward; a few are inverted so that their apical dendrites extend inward. They vary in size from small to the giant Betz's cells.
• stellate cell : cell having a star-shaped appearance produced by numerous processes that extend in different directions in the granular layers
• granule cells : diminutive stellate cells found chiefly in the granular layers
• fibra associationis / association or association neurofiber / neurofibra associationis : one of the nerve fibers connecting different cortical areas within one hemisphere
• fibrae associationis breves / short association or arcuate fibers : association fibers that connect adjacent areas of the cortex
• fibrae arcuatae cerebri / arcuate fibers of cerebrum : short association fibers within the cerebral cortex, connecting adjacent gyri.
• fibrae associationis longae / long association or arcuate fibers : association fibers connecting areas of the cortex that are not adjacent
• fibrae associationis telencephali / association fibers of telencephalon : nerve fibers that interconnect portions of the cerebral cortex within a hemisphere
• fibra commissuralis / commissural fiber or neurofiber / neurofibra commissuralis : one of the nerve fibers which pass between the cortex of opposite hemispheres of the brain, or between 2 sides of the brain stem or spinal cord
• fibrae commissurales telencephali / commissural fibers of telencephalon : the nerve fibers that interconnect regions of the two hemispheres, crossing the median plane
Anatomy :
• sulci cerebri / sulci of cerebrum / cerebral sulci or fissures : the furrows between the cerebral gyri.
• sulci interlobares cerebri / interlobar sulci of cerebrum : the sulci that separate the lobes of the brain from each other.
• zygal fissure : a cerebral fissure that consists of 2 portions united by a short perpendicular third portion.
• lobi cerebrales or cerebri / cerebral lobes : the well defined areas of the cerebral cortex, demarcated by fissures, sulci, and arbitrary lines, including the frontal, temporal, parietal, and occipital lobes
• gyri cerebri / gyri of cerebrum / cerebral gyri : the tortuous convolutions of the surface of the cerebral hemispheres, caused by infolding of the cortex and separated by the fissures or sulci. Many are constant enough that they have been given special names.
• lobus frontalis / frontal lobe : the anterior portion of the cerebral hemisphere, extending from the frontal pole to the sulcus centralis.
• sulcus frontalis inferior / inferior frontal sulcus : a short longitudinal sulcus that separates the inferior and middle frontal gyri.
• sulcus frontalis superior / superior frontal sulcus : a longitudinal sulcus that separates the middle and superior frontal gyri.
• precentral sulcus / sulcus precentralis : a vertical sulcus on the convex surface of a cerebral hemisphere, separating the precentral gyrus from the remainder of the frontal lobe.
• sulcus olfactorius lobi frontalis / olfactory sulcus of frontal lobe : a straight parasagittal sulcus on the inferior surface of the frontal lobe, lodging the olfactory bulb and tract, and separating the gyrus rectus from the gyri orbitales.
• orbital sulci of frontal lobe / sulci orbitales lobi frontalis : irregular sulci between the orbital gyri of the frontal lobe.
• gyrus frontalis inferior / inferior frontal gyrus : a convolution of the frontal lobe below the inferior frontal sulcus; it is divided by the anterior and ascending branches of the lateral sulcus into orbital, triangular, and opercular parts (including Brodmann's area 44 / Broca's  motor speech area).
• gyrus frontalis medialis / medial frontal gyrus / marginal gyrus of Turner / gyrus marginalis : the medial surface of the frontal lobe, separated from the cingulate gyrus by the cingulate sulcus, and continuous with the superior frontal gyrus above and the gyrus rectus below.
• gyrus frontalis medius / middle frontal gyrus : a convolution of the frontal lobe between the superior and inferior frontal sulci, extending anteriorly from the precentral gyrus; a longitudinal sulcus is often present, dividing the gyrus into superior and inferior parts.
• gyrus frontalis superior / superior frontal gyrus : a convolution of the frontal lobe above the superior frontal sulcus, extending anteriorly from the precentral gyrus.
• Flechsig's primordial zones : the cortex of the ascending frontal gyrus and the ascending parietal gyrus of the brain
• gyri orbitales / orbital gyri : the various irregular convolutions lateral to the olfactory sulcus on the orbital surface of the frontal lobe.
• gyrus precentralis / precentral gyrus / anterior central gyrus : the convolution of the frontal lobe lying between the precentral and central sulci; the primary motor area of the cerebral cortex
• stria diagonalis (Broca) / diagonal band of Broca / band of Broca, bandaletta diagonalis (Broca) / Broca's diagonal band : a band of nerve fibers that forms the caudal zone of the anterior perforated substance where it adjoins the optic tract, which is continuous caudolaterally with the periamygdaloid area and rostromedially passes above the optic chiasm to blend with the paraterminal gyrus
• anterior parolfactory sulcus : a sulcus on the medial surface of the cerebral hemisphere, between the area parolfactoria behind and the inferior frontal gyrus in front.
• posterior parolfactory sulcus : a curved sulcus on the medial surface of the cerebral hemisphere, below the splenium of the corpus callosum and between the gyrus paraterminalis and the area parolfactoria.
• sulcus centralis cerebri / central sulcus of cerebrum / fissure of Rolando : a relatively deep, nearly vertical sulcus on the cerebral hemisphere, which separates the frontal from the parietal lobe.
• sulcus lateralis cerebri / lateral cerebral sulcus / sulcus Sylvii / fissure or fossa of Sylvius / sylvian fissure or fossa : a deep cleft beginning at the anterior perforated substance, extending laterally between the temporal and frontal lobes, and turning posteriorly between the temporal and parietal lobes. It divides into posterior, ascending, and anterior branches
• basisylvian fissure : the part of the lateral sulcus between the temporal lobe and the orbital surface of the frontal bone
• presylvian fissure : the anterior branch of the lateral cerebral sulcus.
• Broca's fissure : a term loosely applied to the anterior and ascending rami of the cerebral lateral sulcus which invade the left inferior frontal gyrus
• lobus parietalis / parietal lobe : the upper central lobe of the cerebral hemisphere, separated from the temporal lobe below by the lateral sulcus, but continuous at the posterior end of that sulcus, and separated from the frontal lobe by the central sulcus. Behind, it is continuous with the occipital lobe on the lateral surface, but separated from it by the parietooccipital sulcus on the medial surface.
• parietal gyrus : any one of the convolutions into which the surface of the parietal lobe is divided.
• gyrus angularis / angular gyrus / pli courbe : a convolution of the inferior parietal lobule, arching over the posterior end of the superior temporal sulcus and continuous with the middle temporal gyrus
• most people understand that the proverb 'The grass is always greener on the other side' has a deeper, more general meaning: someone else's situation always looks more attractive than your own. But people with defects in the left angular gyrus take such sentences literally. The walnut-sized area, located above and behind the left ear, is needed to understand the deeper meaning behind proverbs and metaphors. Although the area is not the only part of the brain involved in processing metaphors, it's the main player of the orchestra. 4 patients who had a defect in the left angular gyrus as a result of a stroke or tumour, but were otherwise normal, were asked to explain the deeper meaning behind 20 proverbs and metaphors. The patients took most of the phrases literally, whereas 3 patients with lesions in different brain areas correctly interpreted the deeper meaning. When asked, for example, about the meaning behind 'All that glitters is not gold', one person with a deficient left angular gyrus said, "The deep meaning is that we have to be very careful when buying jewellery. It makes sense that the gyrus is involved in understanding metaphors. It is located next to areas of the cortex that process hearing, vision and touch, making it a good candidate for integrating completely different sensations and extracting a common, abstract meaning from them. To test this prediction, Ramachandran's team tested the patients' ability to translate one kind of sensory information into another, such as shapes into sounds. They found that the patients couldn't associate an image of sawtooths with the sound 'rrrrrrrr' or an image of speckled dots with the sound 'shhhhhh'. Normal people can make the connection between the sensations, even though they have nothing more in common than the abstract concept of jaggedness or fuzziness. This suggests that the left angular gyrus helps humans to think in abstract terms. The area is much larger in humans than in other primates. Any monkey or ape can reach for a peanut, but only humans can reach for the stars, or even understand what that means. Neuroimaging studies have implicated several areas, including the left angular gyrus, in the processing of metaphors. But activation in an area does not prove it is a necessary part of the process, which is what makes Ramachandran's study so important: it shows the left angular gyrus is indispensable. Ramachandran now wants to study the role of the right angular gyrus, which could be more involved in the interpretation of spatial metaphors such as 'having a big heart'. This would be consistent with the notion that the right hemisphere of the brain tends to process spatial information^ref.
• postcentral sulcus / sulcus postcentralis : a sulcus on the superolateral surface of the cerebrum, separating the postcentral gyrus from the remainder of the parietal lobe.
• gyrus postcentralis / postcentral gyrus / posterior central gyrus / ascending parietal gyrus : the convolution of the parietal lobe lying between the central and postcentral sulci; the primary sensory area of the cerebral cortex
• precuneus : a small wedge-shaped convolution on the medial surface of the parietal lobe of the cerebrum, bounded posteriorly by the medial part of the parietooccipital sulcus and anteriorly by the paracentral lobule.
• precuneal fissure : a sulcus in the precuneus.
• subparietal sulcus / sulcus subparietalis :  a sulcus on the medial surface of a cerebral hemisphere, above the splenium of the corpus callosum, separating the precuneus from the cingulate gyrus.
• sulcus cinguli / sulcus of cingulum / cingulate sulcus : a long, irregularly shaped sulcus on the medial surface of a hemisphere, which separates the cingulate gyrus below from the medial frontal gyrus and the paracentral lobule above. At its posterior end it turns up to form a marginal part between the precuneus and the paracentral lobule.
• adoccipital fissure : an inconstant sulcus which crosses the caudal part of the precuneus and joins the occipital fissure.
• paracentral gyrus / gyrus paracentralis / lobulus paracentralis / paracentral lobule : a lobe on the medial surface of the cerebral hemisphere, continuous with the precentral and postcentral gyri of the frontal and parietal lobes, and limited below by the cingulate sulcus; it is composed of sensorimotor cortex, chiefly for the lower limb and genitalia
• lobus temporalis / temporal lobe : the lower lateral lobe of the cerebral hemisphere, lying below the posterior ramus of the lateral sulcus, lateral to the collateral sulcus, and merging behind with the occipital lobe on the lateral and inferior surfaces
• amygdaline fissure : a slight groove inconstantly present near the extremity of the temporal lobe.
• transtemporal fissure : an occasional short fissure on the lateral surface of the temporal lobe.
• gyrus fusiformis / fusiform gyrus : a gyrus of the temporal lobe on the inferior surface of the hemisphere between the inferior temporal gyrus and the parahippocampal gyrus. It consists of a lateral and a medial part, called gyrus occipitotemporalis lateralis and gyrus occipitotemporalis medialis
• gyrus supramarginalis / supramarginal gyrus : the convolution of the inferior parietal lobe that curves around the upper end of the posterior branch of the lateral fissure and is continuous behind it with the superior temporal gyrus.
• gyrus temporalis superior / superior temporal gyrus : the convolution of the temporal lobe lying between the superior temporal sulcus and the lateral sulcus, continuous posteriorly with the supramarginal gyrus.
• gyrus temporalis medius / middle temporal gyrus : the convolution of the temporal lobe lying between the superior and the inferior temporal sulci; it is continuous posteriorly with the angular gyrus.
• subtemporal fissure : an occasional fissure in the inferior and middle temporal convolutions.
• gyrus temporalis inferior / inferior temporal gyrus : the convolution of the temporal lobe lying between the inferior temporal sulcus and the lateral occipitotemporal gyrus, the two gyri being continuous at the inferolateral margin of the temporal lobe.
• gyri temporales transversi / transverse temporal gyri / Heschl's gyri or convolutions : the transverse convolutions marking the posterior extremity of the superior temporal gyrus and lying mostly in the lateral sulcus; usually two, anterior and posterior, but sometimes single on one or both sides
• gyrus temporalis transversus anterior / anterior transverse temporal gyrus : the anterior, more marked, of the 2 transverse temporal gyri, where 2 exist; it represents the cortical center for hearing
• gyrus temporalis transversus posterior / posterior transverse temoral gyrus : the posterior of the two transverse temporal gyri, where two exist
• sulcus temporalis inferior / inferior temporal sulcus : a longitudinal sulcus on the lateral surface of the temporal lobe, separating the middle and the inferior temporal gyri
• sulcus temporalis superior / superior temporal sulcus : a longitudinal sulcus on the lateral surface of a cerebral hemisphere, passing posteriorly from the temporal pole, separating the superior and the middle temporal gyri and ending in the gyrus angularis
• sulcus temporalis transversus / transverse temporal sulcus : an irregularly vertical sulcus in the part of the temporal lobe that lies within the lateral sulcus; sometimes occurring as a pair.
• sulcus occipitalis anterior / anterior occipital sulcus : a variable, vertically disposed furrow on the convex surface of the cerebrum, which by some is taken as the line of division between the parietal and the occipital lobes.
• parietooccipital sulcus / sulcus parietooccipitalis / parietooccipital fissure : a sulcus in the medial surface of each cerebral hemisphere, running upward from the calcarine sulcus and marking the boundary between the cuneus and precuneus, and also between the parietal and occipital lobes
• lobus occipitalis / occipital lobe : the posterior portion of the cerebral hemisphere, on the medial surface extending from the posterior pole to the parietooccipital fissure but on the lateral surface continuous with the parietal lobe superiorly and with the temporal lobe inferiorly.
• lunate sulcus / sulcus lunatus : a small semilunar furrow sometimes seen on the lateral surface of the occipital lobe of the cerebrum; this sulcus is conspicuous in the brain of certain apes and was called by Reidinger Affenspalte [Ger. “ape fissure”].
• gyrus descendens : the raised area posterior to the inferior and superior occipital gyri and anterior to the lunate sulcus when that is present.
• gyrus lingualis / lingual gyrus / infracalcarine gyrus : a gyrus of the occipital lobe on the inferior surface of the hemisphere, forming the inferior lip of the calcarine sulcus and, with the cuneus, the visual cortex; it is continuous anteriorly with the parahippocampal gyrus.
• calcarine sulcus / sulcus calcarinus / calcarine fissure : a sulcus on the medial surface of the occipital lobe, separating the cuneus from the lingual gyrus
• polar sulcus : any of the small fissures which surround the posterior end of the calcarine sulcus.
• inferior occipital gyrus : the lower of the two gyri separated by the lateral occipital sulcus on the lateral aspect of the occipital lobe.
• superior occipital gyrus : the upper of the two gyri separated by the occipital lateral sulcus on the lateral aspect of the occipital lobe.
• gyrus occipitotemporalis lateralis / lateral occipitotemporal gyrus : the lateral portion of the gyrus fusiformis on the inferior surface of the cerebral hemisphere, separated from the medial portion by the occipitotemporal sulcus, and continuous laterally with the inferior temporal gyrus.
• sulci occipitales laterales / lateral occipital sulci : horizontal furrows that divide the lateral occipital gyri into upper and lower portions
• sulci occipitales superiores / superior occipital sulci : irregular sulci associated with the superior occipital gyri.
• gyrus occipitotemporalis medialis / medial occipitotemporal gyrus : the medial portion of the gyrus fusiformis on the inferior surface of the cerebral hemisphere, separated from the lateral portion by the occipitotemporal sulcus, and from the parahippocampal gyrus by the collateral sulcus.
• sulcus occipitalis transversus / transverse occipital sulcus : a vertical sulcus in back of the gyrus angularis, which may help to form the anterior boundary of the occipital lobe or may lie within it
• occipitotemporal sulcus / sulcus occipitotemporalis : a longitudinal sulcus on the inferior surface of the temporal lobe that separates the inferior temporal gyrus.
• limbic system : a term loosely applied to a group of brain structures common to all mammals (including the hippocampus and dentate gyrus with their archaeocortex, the cingulate gyrus and septal areas, and the amygdala), associated with olfaction but of greater importance in other activities, such as autonomic functions and certain aspects of emotion and behavior
• lobus limbicus / limbic lobe : the component parts and connections of the limbic system
• gyrus fornicatus : the marginal portion of the cerebral cortex on the medial aspect of the hemisphere; it forms a major part of the limbic system.
• cingulate area : an important component of the limbic system comprising :
• gyrus cinguli / cingulate or callosal gyrus / gyrus callosus or cingulatus : an arch-shaped convolution closely related to the surface of the corpus callosum, from which it is separated by the callosal sulcus
• isthmus gyri cingulatus / isthmus gyri cinguli / isthmus of cingulate gyrus : the constricted portion of the cingulate gyrus, connecting with the parahippocampal gyrus in the region of the splenium of the corpus callosum
• gyrus hippocampi or parahippocampalis / parahippocampal or hippocampal gyrus : a convolution on the inferior surface of each cerebral hemisphere, lying between the hippocampal and collateral sulci
• uncus gyri fornicati / uncus gyri hippocampi / uncus gyri parahippocampalis : the medially curved anterior end of the parahippocampal gyrus
• uncinate gyrus : the anterior part of the inferior surface of the uncus, separated from the intralimbic gyrus by Giacomini's band.
• intralimbic gyrus : the posterior part of the inferior surface of the uncus, separated from the uncinate gyrus by Giacomini's band.
• rhinal sulcus / sulcus rhinalis : a fissure on the inferior surface of the hemisphere, separating the anterior part of the parahippocampal gyrus from the rest of the temporal lobe.
• hippocampal fissure or sulcus / sulcus hippocampalis or sulcus hippocampi : the sulcus that extends from the splenium of the corpus callosum almost to the tip of the temporal lobe, and forms the medial boundary of the hippocampal gyrus
• collateral sulcus / sulcus collateralis / collateral fissure : a longitudinal sulcus on the inferior surface of the cerebral hemisphere between the fusiform gyrus and the hippocampal gyrus
• gyrus dentatus / dentate gyrus : a serrated strip of gray matter under the medial border of the hippocampus and in its depths; it is an archaeocortex which develops along the edge of the hippocampal fissure and which consists of molecular, granular, and polymorphic layers
• hippocampus / cornu ammonis [L. “horn of Ammon”] : a curved elevation of gray matter extending the entire length of the floor of the temporal horn of the lateral ventricle. Starting on its ventricular aspect, the hippocampus is usually considered to comprise 7 sublayers:
• ependyma
• alveus
• stratum oriens
• stratum pyramidale
• Schaffer collaterals : branches of the axons of the stratum pyramidale of the hippocampus, some of which end on cells in the stratum oriens, but many of which pass into the stratum moleculare.
• stratum radiatum
• stratum lacunosum
• stratum moleculare
In the mammalian hippocampus, a region important for navigation, context-dependent learning and episodic memory, thousands of new granule cells are produced per day, with the exact number depending on environmental conditions and physical exercise. The survival of these neurons is improved by learning and conversely learning may be promoted by neurogenesis. Young granule cells in the adult hippocampus differ substantially from mature granule cells in both active and passive membrane properties. In young neurons, T-type Ca²⁺ channels can generate isolated Ca²⁺ spikes and boost fast Na⁺ action potentials, contributing to the induction of synaptic plasticity. Associative long-term potentiation (LTP) can be induced more easily in young neurons than in mature neurons under identical conditions. Thus, newly generated neurons express unique mechanisms to facilitate synaptic plasticity, which may be important for the formation of new memories^ref . The hippocampus is composed of anatomically heterogeneous subregions. These regions differ in their anatomical inputs as well as in their internal circuitry. A major feature of the CA3 region is its recurrent collateral circuitry, by which the CA3 pyramidal cells make excitatory synaptic contacts on each other. In contrast, pyramidal cells in the CA1 region are not extensively interconnected. Although these differences have inspired numerous theoretical models of differential processing capacities of these two regions, there have been few reports of robust differences in the firing properties of CA1 and CA3 neurons in behaving animals. The most extensively studied of these properties is the spatially selective firing of hippocampal 'place cells'. Here we report that in a dynamically changing environment, in which familiar landmarks on the behavioural track and along the wall are rotated relative to each other, the population representation of the environment is more coherent between the original and cue-altered environments in CA3 than in CA1. These results demonstrate a functional heterogeneity between the place cells of CA3 and CA1 at the level of neural population representations^ref.
• gyrus fasciolaris / fasciolar gyrus / fasciola cinerea : a posterior and upward extension of the dentate gyrus, forming a transitional area between the dentate gyrus and the indusium griseum
• fimbria hippocampi / corpus fimbriatum hippocampi : the band of white matter along the medial edge of the ventricular surface of the hippocampus
• Papez circuit : a neuronal circuit in the limbic system, consisting of the hippocampus, fornix, mammillary body, anterior thalamic nuclei, and cingulate gyrus; postulated by Papez to be involved with the experiencing of emotions and responses to them.
• insula of Reil / lobus insularis / insular lobe : the portion of the cerebral cortex lying deep in the lateral sulcus, almost surrounded by the circular sulcus, which is covered over and hidden from view by juxtaposition of the opercula
• limen insulae / limen of insula / insular threshold : the point at which the cortex of the insula is continuous, on the inferior surface of the cerebral hemisphere, with the cortex of the frontal lobe
• sulcus centralis insulae / central sulcus of insula : a deep, oblique furrow which divides the insula into a larger anterior and a smaller posterior part.
• Burdach's fissure : the groove between the lateral surface of the insula and the inner surface of the operculum.
• circular sulcus of insula / sulcus circularis insulae : a fissure that almost surrounds the insula (lobus insularis) and separates it from the opercula.
• gyri insulae / insular gyri : the gyri that are found on the surface of the insula, including the gyrus longus insulae and the gyri breves insulae.
• gyri breves insulae / short gyri of insula / preinsular gyri : the short, rostrally placed gyri on the surface of the insula
• gyrus longus insulae / long gyrus of insula : the long, occipitally directed gyrus on the surface of the insula.
• gyrus geniculi : a vestigial gyrus at the anterior end of the corpus callosum.
• interlocking gyri : small gyri in the opposing walls of the central sulcus which interlock with each other like gears.
• gyrus olfactorius lateralis / lateral olfactory gyrus : the layer of gray substance covering the lateral olfactory stria.
• gyrus olfactorius medialis / medial olfactory gyrus : the layer of gray substance covering the medial olfactory stria.
• striae olfactoriae / olfactory striae : the radiating fibers of the olfactory tract, which diverge into a lateral and a medial band at the olfactory trigone and border the anterior perforated substance; the bands are covered by the lateral and medial olfactory gyri, respectively
• intermediate olfactory stria : a small band of fibers that pass from the center of the olfactory trigone to penetrate the anterior perforated substance; its presence is variable
• gyrus paraterminalis / paraterminal gyrus : a thin sheet of gray substance in front of and ventral to the genu of the corpus callosum
• gyrus rectus / straight gyrus : a convolution on the orbital surface of the frontal lobe, medial to the olfactory sulcus and continuous with the medial frontal gyrus on the medial surface.
• subcallosal gyrus / area subcallosa / subcallosal area : a small area of cortex on the medial surface of each cerebral hemisphere, between the anterior and posterior parolfactory sulci..
• gyri transitivi cerebri / annectant or annectent gyri : various small folds on the cerebral surface that are too inconstant to bear special names
Tracts :
• corticohypothalamic tract : a diffuse collection of fibers that arise from various parts of the frontal lobe and are distributed directly to the hypothalamus.
• fibrae thalamoparietales / thalamoparietal fibers : nerve fibers that project from the parietal lobe through the posterior limb of the internal capsule to end in the thalamus.
• fibrae corticothalamicae / corticothalamic fibers : nerve fibers that project from the cerebral cortex through the centrum semiovale to terminate in the thalamus.
• corticorubral tract : a group of fibers passing from the cerebral cortex to the red nucleus.
• fibrae corticorubrales / corticorubral fibers : nerve fibers that descend from the cortex of the frontal lobe through the posterior limb of the internal capsule to terminate in the red nucleus.
• external corticotectal tract : a tract of efferent fibers from visual association areas of the cortex, running transversely into the zonal layer of the superior colliculus.
• internal corticotectal tract : a tract of efferent fibers from visual association areas of the cortex, running through the intermediate gray and white layers of the superior colliculus and carrying impulses to muscles controlling eye coordination.
• tractus corticopontinus / corticopontine tract : the collection of corticopontine fibers (fibrae corticopontinae), arising in various areas of the cerebral cortex, particularly from areas involved in movement, and projecting to the pons.
• fibrae corticopontinae / corticopontine fibers : nerve fibers that arise in the cerebral cortex of the frontal, temporal, parietal, and occipital lobes, descend in the internal capsule and cerebral peduncle, and terminate at different levels in the pontine nuclei where they are relayed chiefly to the opposite cerebellar hemisphere. Collectively called corticopontine tract / tractus corticopontinus.
• fibrae frontopontinae / frontopontine fibers / Arnold's prefrontopontocerebellar way : nerve fibers that arise in the frontal lobe of the cerebral hemisphere and traverse the anterior limb of the internal capsule and peduncle, ending in the pontine nuclei. Together they form the tractus frontopontinus / frontopontine tract
• fibrae parietotemporopontinae / parietotemporopontine fibers
• fibrae parietopontinae / parietopontine fibers : nerve fibers that arise in the cerebral cortex of the parietal lobe, descend in the sublentiform part of the posterior limb of the internal capsule to become constituent fibers of the basis pedunculi cerebri of the ventral part of the cerebral peduncle, and end in the pontine nuclei
• fibrae temporopontinae / temporopontine fibers : nerve fibers that arise in the cerebral cortex of the temporal lobe, descend in the sublentiform part of the posterior limb of the internal capsule to become constituent fibers of the basis pedunculi cerebri of the ventral part of the cerebral peduncle, and end in the pontine nuclei.
• tractus interstitiospinalis / interstitiospinal tract : a tract of nerve fibers that descends from the interstitial nucleus into the spinal cord as part of the medial longitudinal fasciculus.
• tractus pyramidalis / pyramidal or corticospinal tract of medulla oblongata / fasciculus pyramidalis medullae oblongatae / pyramidal system : a term applied to several groups of fibers (corticonuclear, corticospinal, and corticoreticular) arising chiefly in the sensorimotor regions of the cerebral cortex and descending in the internal capsule, cerebral peduncle, and pons to the medulla oblongata, the corticoreticular fibers descending with the corticospinal fibers and synapsing with cells of the reticular formation and the corticonuclear fibers synapsing with motor nuclei throughout the brain stem. Most of the corticospinal fibers cross in the decussation of the pyramids and descend in the spinal cord as the lateral corticospinal tract; most of the uncrossed fibers form the anterior corticospinal tract; both end by synapsing with internuncial and motor neurons. The pyramidal tract is a phylogenetically new tract, most prominent in humans, and provides for direct cortical control and initiation of skilled movements, especially those related to speech and involving the hand and fingers
• corticobulbar or corticonuclear tract : the nerve fiber tract formed by fibers (corticonuclear fibers) of the pyramidal tract that arise in the cerebral cortex, descend in the internal capsule, and synapse in the various motor nuclei of the mesencephalon (corticomesencephalic tract), pons (corticopontine tract), and medulla oblongata (corticobulbar tract sensu strictu)
• aberrant bundles : collections of pyramidal fibers leaving the corticonuclear tract at successive levels of the brain stem, and giving off fibers to the motor nuclei of the cranial nerves.
• fibrae corticonucleares / corticonuclear fibers / corticobulbar fibers : longitudinal fibers of the pyramidal tract that arise in the cerebral cortex, descend in the internal capsule, and synapse in the various motor nuclei of the mesencephalon, pons, and medulla oblongata. Together they form the corticonuclear tract
• fibrae corticoreticulares / corticoreticular fibers : nerve fibers that arise chiefly in the sensorimotor areas of the cerebral cortex, descend with corticospinal fibers, and synapse with cells of the reticular formation, especially in the pons and medulla oblongata.
• corticospinal tracts of spinal cord / pyramidal tracts of spinal cord : the 2 spinal cord tracts that are continuations of the pyramidal tract of the medulla oblongata
• fibrae corticospinales / corticospinal fibers : longitudinal fibers that arise in the cerebral cortex, descend in the internal capsule, mesencephalon, pons, and pyramids of the medulla oblongata, and which form, upon reaching the spinal cord, ...
• tractus corticospinalis or pyramidalis lateralis / crossed or lateral corticospinal or pyramidal tract : a group of nerve fibers in the lateral funiculus of the spinal cord, originating in the cerebral cortex
• tractus corticospinalis or pyramidalis anterior or ventralis / anterior, direct or ventral  corticospinal or pyramidal tract : a group of nerve fibers in the anterior funiculus of the spinal cord, originating in the cerebral cortex
• commissurae encephali / encephalic commissures : site of union of cerebral hemispheres across the median plane of the body.
• corpus callosum / commissura magna cerebri : an arched mass of white matter, found in the depths of the longitudinal fissure, composed of 3 layers of fibers, the central layer consisting primarily of transverse fibers connecting the cerebral hemispheres; its subsections, from anterior to posterior, are called the ...
• rostrum corporis callosi / rostrum of corpus callosum : the anterior and lower end of the corpus callosum.
• lamina rostralis / rostral lamina : the thin terminal part of the rostrum of the corpus callosum passing down in front of the anterior commissure to the anterior perforated substance and the paraterminal gyrus.
• genu corporis callosi / genu of corpus callosum : the sharp ventral curve at the anterior end of the trunk of the corpus callosum.
• truncus corporis callosi / trunk of corpus callosum : the main central portion of the corpus callosum as distinguished from the rostrum and the splenium.
• splenium corporis callosi : the posterior rounded end of the corpus callosum; it conveys visual information between the 2 cerebral hemispheres.
Tracts :
• radiatio corporis callosi / radiation of corpus callosum : the projection of fibers from the corpus callosum to all parts of the neopallium.
• stria longitudinalis lateralis corporis callosi / lateral longitudinal stria of corpus callosum : one of two slender bands of myelinated fibers which form longitudinal ridges in the indusium griseum on the superior aspect of each half of the corpus callosum.
• stria longitudinalis medialis corporis callosi / medial longitudinal stria of corpus callosum : one of two slender bands of myelinated fibers which form longitudinal ridges in the indusium griseum on the superior aspect of each half of the corpus callosum.
• transverse striae of corpus callosum : transverse bands of fibers on the upper surface of the corpus callosum
• sulcus corporis callosi / sulcus of corpus callosum : a sulcus encircling the convex aspect of the corpus callosum at the bottom of the longitudinal cerebral fissure.
• fasciculus longitudinalis inferior cerebri / inferior longitudinal fasciculus of cerebrum : a bundle of assumed association fibers interconnecting the cortex of the occipital and temporal lobes, extending through the occipital and temporal lobes of the cerebrum, and consisting chiefly of geniculocalcarine projection fibers.
• fasciculus longitudinalis superior cerebri / superior longitudinal fasciculus of cerebrum / fasciculus arcuatus / arcuate fasciculus : a bundle of association fibers in the cerebrum, extending from the frontal lobe to the posterior end of the lateral sulcus, and interrelating the cortex of the frontal, temporal, parietal, and occipital lobes
• fasciculus occipitofrontalis inferior / inferior occipitofrontal fasciculus : a collection of association fibers in the inferior part of the extreme capsule near the uncinate fasciculus, connecting various inferior gyri of the temporal and frontal lobes
• fasciculus occipitofrontalis superior / superior occipitofrontal fasciculus / fasciculus subcallosus / subcallosal fasciculus : a collection of association fibers lying just internal to the intersection of the internal capsule and corpus callosum, interconnecting the cortex of the occipital and temporal lobes with that of the insula and frontal lobe, and probably comprising a significant part of the tapetum
• fasciculus parieto-occipitopontinus : a bundle of nerve fibers that arise in the parietal and occipital lobes and pass through the retrolenticular part of the posterior limb of the internal capsule to end in the pontine nuclei.
• unciform fasciculus / uncinate fasciculus / fasciculus uncinatus : a collection of association fibers which interconnect the cortex of the orbital surface of the frontal lobe with the parahippocampal gyrus and perhaps with the amygdala; other temporofrontal connections probably also exist.
• fornix of brain : the efferent pathway of the hippocampus, projecting chiefly to the mammillary bodies and habenular nuclei; each fornix of the pathway is an arched tract that is united under the corpus callosum with the other fornix, so that together they comprise :
• columna fornicis / fornix column / anterior pillar of fornix, and column of fornix : either of the two columnar masses of fibers diverging from the anterior end of the body of the fornix to descend into the diencephalon
• corpus fornicis / body of fornix : the middle part of the fornix of the cerebrum, formed by fusion of the two lateral halves under the corpus callosum.
• crus fornicis / crus of fornix : either of the two flattened bands of white substance of the brain that are in close contact with the splenium and that unite under the posterior part of the body of the corpus callosum to form the body of the fornix.
• commissura fornicis / commissure of fornix / hippocampal commissure : a band of fibers connecting the hippocampi of the 2 sides through the body of the fornix
• commissura anterior / anterior commissure / commissura rostralis / rostral commissure : a bundle of myelinated nerve fibers passing transversely through the lamina terminalis and connecting symmetrical parts of the two cerebral hemispheres; it consists of a smaller anterior part (pars anterior commissurae anterioris) and a larger posterior part (pars posterior commissurae anterioris)
• precommissural septum / septum precommissurale or verum : a septum situated anterior to the rostral commissure of the cerebrum, corresponding in part to the paraterminal gyrus, which consists of dorsal, ventral, medial, and caudal nuclear groups
• supraoptic commissures : at least 3 fiber bundles  that crosses the midline of the brain dorsal to the optic chiasm, which have been referred to as commissures but are probably decussations; their connections in humans are uncertain. The official anatomical nomenclature recognizes only :
• commissura supraoptica dorsalis / Meynert's commissure / dorsal or superior supraoptic commissure
• commissura supraoptica ventralis / Gudden's commissure / ventral or inferior supraoptic commissure
• septum pellucidum / pellucid septum / septum lucidum : a triangular double membrane separating the anterior horns of the lateral ventricles of the brain; situated in the median plane, it is bounded by the corpus callosum and the body and columns of the fornix
• lamina septi pellucidi / lamina of septum pellucidum : either of the thin, vertical sheets, separated by a cleftlike space, which constitute the septum pellucidum.
• nucleus septalis lateralis / lateral septal nucleus : a nucleus in the septal area, continuous with the gray lamina of the septum pellucidum; it has afferent and cholinergic efferent connections with a variety of forebrain and brain stem areas including the hippocampus, the lateral hypothalamus, the tegmentum, and the amygdalas
• nucleus septalis medialis / medial septal nucleus : a nucleus in the septal area, coextensive with the diagonal band of Broca; it has afferent and cholinergic efferent connections with a variety of forebrain and brain stem areas including the hippocampus, the lateral hypothalamus, the tegmentum, and the amygdalas
• nucleus triangularis septi / triangular septal nucleus : a nucleus of nerve cells of the caudal region of the septum pellucidum.
• cavum septi pellucidi / cave or cavity of septum pellucidum / Duncan's or Vieussens' ventricle / fifth ventricle / pseudocele / pseudocoele / pseudoventricle / ventricle of Sylvius (the median cleft between the 2 laminae of the septum pellucidum
• lamina terminalis hypothalami / terminal lamina of hypothalamus / terminal plate : a thin plate derived from the telencephalon extending upward from the optic chiasm and preoptic recess, and forming the anterior wall of the third ventricle of the cerebrum
• stria terminalis / terminal stria : a band of fibers along the lateral margin of the ventricular surface of the thalamus, covering the thalamostriate vein and, following the course of the vein, marking the line of separation between the thalamus and the caudate nucleus; it extends from the region of the interventricular foramen to the temporal horn of the lateral ventricle, carrying fibers from the amygdalas to the septal, hypothalamic, and thalamic areas
• fibrae striae terminalis / fibers of stria terminalis : the myelinated nerve fibers that make up the stria terminalis
• nucleus striae terminalis / bed nucleus of stria terminalis : the collection of scattered groups of neurons between the fibers near the anterior end of the stria terminalis; they serve a relay function
• nucleus basalis telencephali / basal nucleus of telencephalon / nucleus basalis of Meynert / Meynert's nucleus : a group of neurons in the basal forebrain that has wide projections to the neocortex and is rich in acetylcholine and choline acetyltransferase. It undergoes degeneration in Parkinson's disease (PD) and Alzheimer's disease
• substantia perforata anterior / anterior perforated substance / olfactory area / substantia perforata rostralis / rostral perforated substance : an area on the base of the brain anterior to each optic tract, containing numerous perforations through which small branches of the anterior and middle cerebral arteries are transmitted to deeper structures
• islands or islets of Calleja / olfactory islands : discrete collections of pyramidal and polymorphic cells in the caudal part of the anterior perforated substance (olfactory tubercle)
• substantia innominata of Reichert or of Reil : nerve tissue immediately inferior to the anterior perforated substance, and anterior to the globus pallidus and ansa lenticularis
• nuclei basales / basal ganglia or nuclei : specific interconnected groups of masses of gray substance deep in the cerebral hemispheres and in the upper brain stem. Although various subcortical nuclei have been considered to be part of the basal nuclei, in official anatomical terminology the term includes the ...
• capsula interna / internal capsule : a fanlike mass of white fibers that separates the lentiform nucleus laterally from the head of the caudate nucleus, the dorsal thalamus, and the tail of the caudate nucleus medially. The internal capsule is known to carry corticofugal (efferent) fibers from the cerebral cortex; its exact role in carrying afferent fibers to the cortex remains uncertain; it consists of ...
• crus anterius capsulae internae / anterior limb of internal capsule : separates the caudate and the lentiform nuclei; it contains
• anterior thalamic radiations
• frontopontine tract
• subfrontohypothalamic tract
• genu capsulae internae / genu of internal capsule / knee of internal capsule : the blunt angle formed by the union of the 2 limbs of the internal capsule, situated posterior to the caudate nucleus, anterior to the thalamus, and medial to the lentiform nucleus, and containing
• corticonuclear tract
• corticoreticular fibers
• crus posterius capsulae internae / posterior limb of internal capsule : separates the thalamus from the lentiform nucleus; its main known function is the conveyance of corticofugal efferent motor fibers from the cerebral cortex, but it also carries other fiber projections. It consists of
• pars thalamolenticularis or lenticulothalamicus capsulae internae / thalamolenticular part of internal capsule : adjacent to the thalamus and lentiform nucleus, consisting of fibers of the
• corticospinal tract : anterior => posterior location of fibers within capsule corresponds to craniocaudal location of innervated muscles
• thalamic radiations
• corticorubral tract
• corticoreticular tract
• corticothalamic tract
• thalamoparietal fibers (sometimes)
• central thalamic radiations (sometimes)
• external corticotectal tract
• internal corticotectal tract
• pars sublentiformis capsulae internae / sublentiform part of internal capsule / sublenticular or sublentiform limb of internal capsule : lying anterior to the posterior part of the lentiform nucleus, and containing the
• temporopontine fibers
• geniculocalcarine fibers
• auditory radiation fibers
• pars retrolentiformis capsulae internae / retrolentiform part of internal capsule / retrolenticular or retrolentiform limb of internal capsule : resting on the lateral surface of the thalamus behind the lentiform nucleus, and containing
• posterior thalamic radiation
• parietotemporopontocerebellar way
• cortico(occipital)-tuberculus quadrigeminus superior and area 4
• corona radiata : the radiating crown of projection fibers which pass from the internal capsule to every part of the cerebral cortex.
• capsula externa / external capsule : the thin layer of white substance that separates the lateral part of the lentiform nucleus (putamen) from the claustrum
• capsula extrema / extreme capsule : the white matter between the claustrum and the cortex of the insula, containing association fibers between lobes
• corpus striatum / striate body : one of the components of the basal nuclei; specifically, a subcortical mass of gray and white substance in front of and lateral to the thalamus in each cerebral hemisphere. Its name denotes the striate appearance on section of the area, produced by connecting bands of gray substance passing from one of these nuclei to the other through the anterior limb of the internal capsule. The gray substance of this structure is arranged in 2 principal masses :
• lenticular or lentiform nucleus / nucleus lentiformis or lenticularis : the part of the corpus striatum somewhat resembling a biconvex lens, divided into
• putamen : an external, larger, lateral part
• lamina medullaris externa or lateralis corporis striati / external or lateral medullary lamina or stria of corpus striatum : a layer of white substance that separates the lateral globus pallidus from the putamen
• globus pallidus / paleostriatum (the phylogenetically older part of the corpus striatum represented by the globus pallidus) : an internal, smaller, lighter colored medial part, which is in turn subdivided into a smaller, medial, and a larger, lateral part by the lamina medullaris medialis or interna corporis striati / internal or medial medullary lamina or stria of corpus striatum : a layer of white substance that divides the medial portion of the lentiform nucleus (globus pallidus) into a larger, lateral, and a smaller, medial part

Tracts :
• fasciculus lenticularis / lenticular fasciculus : a bundle of pallidofugal nerve fibers that arise from the dorsal surface of the globus pallidus, pass through the internal capsule, traverse field H₂ of Forel, join and mingle with the fibers of the ansa lenticularis, and continue to the nuclei of the ventral thalamus.
• ansa lenticularis : a small fiber tract arising in the globus pallidus of the lenticular nucleus and extending around the medial border of the internal capsule to join and mingle with the fibers of the fasciculus lenticularis, some of which synapse with cells in the subthalamic nucleus, nucleus of the prerubral field (field H of Forel), and the zona incerta, and others of which continue to the ventral nuclei of the thalamus.
• nucleus ansae lenticularis / nucleus of ansa lenticularis : a collection of neurons in the ansa lenticularis as it curves around the medial edge of the globus pallidus.
• caudate nucleus : an elongated, arched gray mass closely related to the lateral ventricle throughout its entire extent and consisting of a head, body, and tail
• corpus nuclei caudati : the part of the caudate nucleus lying in the floor of the pars centralis of the lateral ventricle of the brain, extending posteriorly from the head and continuous with the tail.
• cauda nuclei caudati / tail of caudate nucleus : the part of the caudate nucleus that tapers off from the body, curves around in the roof of the inferior horn of the lateral ventricle, and extends rostrally as far as the amygdala
• claustrum : the thin layer of gray matter lateral to the external capsule of the lentiform nucleus, separating the nucleus from the white substance of the insula; it is mainly composed of spindle cells.
Functional subdivision :
• dorsal striatum is involved in sensorimotor and cognitive functions

Tracts :
• nigrostriate tract / comb bundle : a bundle of nerve fibers extending from the area 9 / substantia nigra pars compacta (SNpc) to the globus pallidus and putamen in the corpus striatum; injury to it may be a cause of parkinsonism. Its interlacing pattern with fibers of the internal capsule gives it a comblike appearance
• strionigral tract : a bundle of fibers from the corpus striatum to the substantia nigra.
• ventral striatum is implicated in motivation and affect (limbic functions)
• nucleus accumbens septi : a collection of pleomorphic cells in the caudal part of the anterior horn of the lateral ventricle of the olfactory tubercle, lying between the head of the caudate nucleus and the anterior perforated substance
• core :
• shell :
• portions of the olfactory tubercle
• ventral and medial portions of the caudate-putamen / neostriatum / striatum (the later developed portion of the corpus striatum represented by the caudate nucleus and the putamen)
• corpus amygdaloideum / amygdala / amygdaloid body or complex / nucleus amygdalae : a small, ovoid complex of nuclei partly covered by the pyriform cortex, within the tip of the temporal lobe, anterior to the inferior horn of the lateral ventricle of the brain; it is part of the limbic system and is classified as a part of the basal nuclei. The amygdaloid body is divided into
• 2 main groups of nuclei, found in
• basolateral part / pars basolateralis corporis amygdaloidei
• basal amygdaloid nucleus
• accessory basal amygdaloid nucleus
• nucleus amygdalae lateralis / lateral amygdaloid nucleus
Tracts : ventral amygdalofugal tract : a diffuse fiber tract connecting the basolateral part of the amygdaloid body with the lateral preoptic and hypothalamic regions.
• corticomedial part / pars corticomedialis corporis amygdaloidei
• nucleus amygdalae centralis / central amygdaloid nucleus, providing the major relay for projections from the amygdala to the brainstem and also receiving numerous return projections
• nucleus amygdalae corticalis / cortical amygdaloid nucleus
• nucleus amygdalae medialis / medial amygdaloid nucleus
Tracts : ansa peduncularis / peduncular loop : a complex grouping of fibers connecting the amygdaloid nucleus, the piriform area, and the anterior part of the hypothalamus, and various thalamic nuclei. The fiber bundles pass below the internal capsule, a principal bundle being the inferior peduncle of the thalamus.
• area amygdaloidea anterior / anterior amygdaloid area : a poorly differentiated transition zone in the corticomedial part of the amygdaloid body, through which the nuclei are continuous with adjacent areas.
It has olfactory connections, is reciprocally connected to the limbic cortex, and projects fibers to the hippocampus, the septum, the thalamus, and especially the hypothalamus

• fissura transversa cerebralis / fissura transversa cerebri / transverse cerebral fissure / great or great transverse fissure of cerebrum / fissure of Bichat : the fissure between the dorsal surface of the diencephalon and the ventral surface of the cerebral hemispheres, produced by the folding back of the hemispheres during their development
• diencephalon / interbrain : the caudal part of the prosencephalon, which largely bounds the third ventricle and connects the mesencephalon to the cerebral hemispheres; each lateral half is divided by the hypothalamic sulcus into ...
• dorsal part
• epithalamus : the caudal part of the roof and the adjoining lateral walls of the third ventricle of the diencephalon, comprising the
• habenula / pineal peduncle : a component of the epithalamus, being the small eminence on the dorsomedial surface of the thalamus, just in front of the dorsal commissure on the lateral edge of the habenular trigone
• habenular sulcus / sulcus habenularis : a groove separating the trigonum habenulae from the upper surface of the thalamus.
• nuclei of habenula / nuclei habenulae : 2 nerve cell groups situated deep to the habenular trigone;
• nucleus habenularis lateralis / lateral habenular nucleus : the more dispersed; it receives fibers from the stris medullaris thalami and projects to the raphe nuclei, reticular formation of mesencephalon, pars compacta of substantia nigra, and hypothalamus and basal forebrain.
• nucleus habenularis medialis / medial habenular nucleus : the more densely packed; it receives fibers from the stria medullaris thalami and projects to the interpeduncular nucleus of the midbrain.
• commissura habenularum / habenular commissure : a band of fibers of the stria medullaris that pass through the habenula of each side to decussate and terminate in the habenula of the other side.
• tractus habenulointerpeduncularis / habenulointerpeduncular or habenulopeduncular tract / fasciculus retroflexus / Meynert's bundle, fasciculus, or tract : a bundle of nerve fibers arising in the habenular nuclei and extending rostroventrally to the interpeduncular nucleus to relay fibers to the reticular formation of the mesencephalon
• pineal body
• commissura posterior / posterior commissure of cerebrum / commissura epithalamica / commissure of epithalamus : a large fiber bundle that crosses the midline of the epithalamus just dorsal to the point where the cerebral aqueduct opens into the third ventricle
• (dorsal) thalamus : a large ovoid mass in the posterior part of the diencephalon forming most of each lateral wall of the third ventricle, composed chiefly of gray substance and associated laminae of white substance. It is divided into anterior, medial, and lateral parts, each part containing groups of nuclei that function as relay centers for sensory impulses and cerebellar and basal ganglia projections to the cerebral cortex. The main groups of thalamic nuclei are the reticular, anterior, median, medial, medullary, intralaminar, ventrolateral, and posterior nuclei. Some authorities consider the subthalamus part of the thalamus and refer to it as the ventral thalamus / thalamus ventralis, calling the posterior part the dorsal thalamus.
• paleothalamus : old thalamus; a term applied occasionally to the phylogenetically older part of the thalamus, i.e., the medial portion which lacks reciprocal connections with the neopallium.
• neothalamus : new thalamus; the phylogenetically new part of the thalamus, i.e., the part connected to the neocortex
• lamina medullaris lateralis thalami / external medullary layer of thalamus : one of 2 layers of myelinated nerve fibers in the dorsal thalami; it covers the lateral surface of the dorsal thalamus and separates it from the internal capsule.
• lamina medullaris medialis thalami / internal medullary layer of thalamus : one of 2 layers of myelinated nerve fibers in the dorsal thalami; it is a vertical sheet of white substance which partially splits anterosuperiorly and separates the medial and lateral nuclei. It contains the intralaminar nuclei.
Nuclei of thalamus : the nuclei and nuclear groups in the thalamus. Groups are
• nuclei anteriores thalami / anterior nuclei of thalamus : the 3 nuclei in the anterior part of the thalamus. Together, they receive connections from the mammillary body and fornix and project fibers to the cingulate body.
• nucleus anteromedialis thalami / anteromedial nucleus of thalamus
• nucleus anteroventralis thalami / anteroventral nucleus of thalamus
• nucleus anterodorsalis thalami / nucleus anterosuperior thalami / anterodorsal nucleus of thalamus
• nuclei dorsales thalami / dorsal nuclei of thalamus : the nuclei forming the posterior end of the dorsal thalamus, including the  ...
• nuclei pulvinares thalami / pulvinar nuclei : a subgroup of the dorsal thalamic nuclei consisting of those that form the prominent, cushion-like medial portion of the posterior extremity of the thalamus (the pulvinar).
• nucleus lateralis posterior thalami / lateral posterior (LP) nucleus of thalamus : a nucleus in the ventral lateral part of the thalamus having major connections with the cingulate gyrus.
• nucleus dorsalis lateralis thalami / lateral dorsal (LD) nucleus of thalamus : a nucleus in the dorsal lateral part of the thalamus having extensive connections with the cerebral cortex
• nuclei mediales thalami / medial nuclei of thalamus : groups of nerve cells lying between the internal medullary lamina laterally and projecting toward the ependymal lining of the third ventricle medially; included are the large nucleus mediodorsalis and a series of smaller nuclei of uncertain significance and connections.
• nucleus mediodorsalis thalami / medial dorsal nucleus of thalamus / dorsomedial nucleus of thalamus : the largest of the medial nuclei of the thalamus, having a rostral magnocellular part and a caudolateral parvocellular part, both of which make extensive intrathalamic connections with most of the other thalamic nuclei
• nuclei mediani thalami / median nuclei of thalamus : small groups of nonspecific nerve cells scattered in the periventricular gray substance, separating the medial part of the thalamus from the ependyma of the third ventricle, and partly forming the interthalamic adhesion; included in the group are the
• nuclei paraventriculares thalami / paraventricular nuclei of thalamus : 2 of the nuclei mediani thalami; they are situated on the dorsomedial wall of the thalamus, juxtaposed to the third ventricle
• nucleus paraventricularis anterior thalami / anterior paraventricular nucleus of thalamus
• nucleus paraventricularis posterior thalami / posterior paraventricular nucleus of thalamus
• nucleus parataenialis thalami / paratenial nucleus of thalamus : one of the median nuclei of the thalamus, situated ventral and medial to the stria medullaris
• nucleus commissuralis rhomboidalis / rhomboid nucleus / nucleus rhomboidalis : one of the median nuclei of the thalamus, bordering the third ventricle and ventral to the central medial nucleus
• nucleus reuniens : one of the median nuclei of the thalamus; it is situated near the interthalamic adhesion, bordering the third ventricle, ventral to the central medial nucleus
• intralaminar nuclei of thalamus / nuclei intralaminares thalami / reticular nuclei of thalamus / nuclei reticulares thalami : the nuclei within the internal medullary lamina of the thalamus, lying between the medial dorsal nucleus above and the lateral posterior nucleus below; included are
• nucleus paracentralis thalami / paracentral nucleus of thalamus : one of the smaller reticular nuclei of the dorsal thalamus, situated ventrolateral to the dorsal medial nucleus and medial to the central lateral nucleus
• nucleus parafascicularis thalami / parafascicular nucleus of thalamus : one of the smaller reticular nuclei of the dorsal thalamus, situated medial to the centromedian nucleus and ventral to the dorsal medial nucleus.
• nucleus centralis lateralis thalami / central lateral (CL) nucleus of thalamus : one of the smaller intralaminar nuclei of the dorsal thalamus, situated in the dorsal part of the internal medullary lamina.
• nucleus centralis medialis thalami / medial central (MC) nucleus of thalamus : one of the smaller intralaminar nuclei, situated medially in the internal medullary lamina.
• nucleus centromedianus thalami / centromedian nucleus of thalamus : the largest and most caudal of the intralaminar nuclei of the dorsal thalamus; its main connections are with the corpus striatum
• nuclei posteriores thalami / posterior nuclear complex of thalamus : groups of nerve cells anterior to the pulvinar, forming an ill-defined complex that receives afferents from the spinothalamic tract and superior and inferior colliculi.
• nuclei ventrales thalami / ventral nuclei of thalamus : a large group of nuclei lying between the internal medullary lamina and the internal capsule; it includes ventral anterior, ventral intermediate, ventral lateral, ventral medial, ventrobasal and other nuclei, which relay impulses to various specific areas of the cerebral cortex.
• nucleus ventralis anterior thalami / ventral anterior (VA) nucleus of thalamus : a nucleus anteriorly located within the ventral nuclei of the thalamus, posterior to the reticular nucleus, anterior to the ventral lateral nucleus, and lateral and medial to the internal and external medullary laminae, respectively; it is subdivided into magnocellular and principal divisions
• nucleus ventralis intermedius thalami / ventral intermediate nucleus of thalamus : a nucleus medially located within the ventral nuclei of the thalamus.
• nuclei ventrales laterales thalami / ventral lateral (VL) nuclei of thalamus / ventral lateral complex of thalamus : nuclei ventrolaterally located within the ventral thalamic nuclei, subdivided into anterior and posterior nuclei
• nuclei ventrales mediales thalami / ventral medial (VM) complex of thalamus : a group of nuclei located in the medial portion of the ventral thalamic nuclei
• nuclei ventrobasales thalami / ventrobasal complex of thalamus / ventral posterior (VP) nuclei of thalamus / nuclei ventrales posteriores thalami : the nuclei that form the posterior ventral part of the ventral nuclei of the thalamus, comprising ...
• nucleus ventralis posterolateralis (VP_l) thalami : the more lateral of the 2 posterior ventral nuclei of the thalamus; it is the terminus of the spinothalamic tract and the medial lemniscus and it projects to the postcentral gyrus.
• nucleus ventralis posteromedialis (VP_m) thalami : the more medial of the 2 posterior ventral nuclei of the thalamus; it is the secondary trigeminal tract and sends axons to the somesthetic area of the postcentral gyrus for the face.
• nucleus reticularis thalami : reticular nucleus of thalamus: a thin layer of cells on the lateral surface of the thalamus, within and lateral to the external medullary lamina.
Tracts :
• tuberohypophysial tract / tuberoinfundibular tract : a group of nerve fibers arising in the cells of the infundibular nucleus and related nuclei of the intermediate hypothalamic region, believed to provide a neurosecretory pathway associated with the neurocontrol of secretory activity by the anterior lobe of the pituitary gland
• adhesio interthalamica / interthalamic adhesion : a mass of gray matter connecting the thalami across the midline of the third ventricle; it develops as a secondary adhesion and is often absent.
• thalamo-olivary tract : a bundle of fibers descending from the thalamus to the olivary nucleus
• thalamocortical fibers or projections / thalamic radiations / radiations of thalamus : sensory nerve fibers that connect the dorsal thalamus to the cerebral cortex, which together form the peduncles of the thalamus
• radiatio thalami anterior / anterior thalamic radiation : the group of thalamocortical fibers of the anterior limb of the internal capsule connecting the medial and anterior thalamic nuclei and the prefrontal area
• radiatio thalami centralis / central or superior thalamic radiation : the group of thalamocortical fibers of the posterior limb of the internal capsule, presumably carrying general sensory impulses from the ventral thalamic nuclei to the postcentral gyrus
• radiatio thalami inferior / inferior thalamic radiation / pedunculus thalamicus inferior / inferior peduncle of thalamus : the smallest of the four thalamic peduncles; it connects the medial geniculate body with certain areas of the cortex of the temporal lobe, forming one of the principal components of the ansa peduncularis
• radiatio thalami posterior / posterior thalamic radiation : the group of thalamocortical fibers of the retrolentiform part of the internal capsule connecting the cortices of the occipital and parietal lobes and the caudal parts of the thalamus.
• stria medullaris thalami / medullary stria of thalamus : a fiber bundle that arises from the subcallosal and paraterminal gyri, the preoptic area, and amygdaloid area, and runs backward along the junction of the dorsal and medial surfaces of the thalamus to reach the habenular nucleus
• thalamic fasciculus / fasciculus thalamicus : a bundle of nerve fibers ascending through field H of Forel to pass dorsal to and partly through the zona incerta, crossing the lower portion of the posterior limb of the internal capsule to reach some of the ventral nuclei of the thalamus; it contains continuations of the ansa lenticularis and the fasciculus lenticularis and dentatothalamic, rubrothalamic, and thalamostriate fibers
• metathalamus : the part of the diencephalon inferior to the caudal end of the dorsal thalamus, comprising ...
• corpus geniculatum laterale / lateral geniculate body / optic thalamus : an eminence of the metathalamus produced by the underlying lateral geniculate nucleus, just lateral to the medial geniculate body. It relays visual impulses from the optic tract to the calcarine cortex and links visual inputs to the nearby midbrain
• lateral geniculate nucleus : a nucleus within the lateral geniculate body, composed of
• nucleus dorsalis corporis geniculati lateralis / dorsal lateral geniculate nucleus : the large dorsal part of the lateral geniculate nucleus, consisting of six concentrically arranged cell layers in a dome-shaped mound, which receive crossed and uncrossed fibers of the optic tract that are connected with the visual cortex
• nucleus ventralis corporis geniculati lateralis / ventral lateral geniculate nucleus / pregeniculate nucleus / nucleus pregeniculatus : the smaller, ventral part of the lateral geniculate nucleus, projecting toward the zona incerta of the ventral thalamus
• radiatio optica / occipitothalamic or optic radiation of Gratiolet / geniculocalcarine tract : a fiber tract that begins at the lateral geniculate body, passes laterally through the pars retrolentiformis of the internal capsule, follows the lateral wall of the lateral ventricle, and finally projects posteriorly to end in the striate area on the medial surface of the occipital lobe on either side of the calcarine sulcus; the radiation provides reciprocal connections and forms part of the posterior thalamic peduncle
• corpus geniculatum mediale / medial geniculate body : an eminence of the metathalamus produced by the underlying medial geniculate nucleus, just lateral to the superior colliculus. It relays auditory impulses from the lateral lemniscus to the auditory cortex.
• nuclei corporis geniculati medialis / medial geniculate nuclei / nuclei of medial geniculate body : nuclei that receive ascending auditory and some nonauditory fibers and project to the auditory cortex
• nucleus dorsalis corporis geniculati medialis / dorsal nucleus of medial geniculate body : the larger, dorsal part of the medial geniculate nucleus, receiving ascending auditory fibers from the inferior colliculus as well as afferent projections from some nonauditory areas of the brain stem, and projecting to the auditory cortex
• nucleus medialis magnocellularis corporis geniculati medialis
• nucleus ventralis corporis geniculati medialis / ventral principal nucleus of medial geniculate body : the principal relay nucleus of the medial geniculate nuclei, receiving ascending auditory fibers from the inferior colliculus and relaying information on sound intensity and frequency and its binaural properties to the auditory cortex.
• radiatio acustica / acoustic or auditory radiation : a fiber tract arising in the medial geniculate nucleus and passing laterally in the sublenticular portion of the internal capsule to terminate in the transverse temporal gyri of the temporal lobe; the radiation provides reciprocal connections and forms part of the caudal peduncle of the thalamus.
• ventral part
• subthalamus : a large ovoid mass in the anterior part of the diencephalon interposed between the dorsal thalamus, hypothalamus, and tegmentum of the mesencephalon; it contains
• nucleus of the lateral geniculate bodies
• nuclei of the medial geniculate bodies
• nucleus subthalamicus / subthalamic nucleus / nucleus of Luys / Luys' body : a biconvex mass of gray matter on the medial side of the junction of the internal capsule and the crus cerebri; its chief connections are with the globus pallidus
• reticular nuclei
• zona reticularis / reticular zone : the inner layer of the adrenal cortex, consisting of cells arranged as clearly anastomosing cords, and abutting the medulla.
• nuclei of areae H (Forel's fields)
Some authorities consider this to be part of the thalamus and refer to it as the ventral thalamus.
Tract : fasciculus subthalamicus / subthalamic fasciculus: a bundle of fibers passing through the internal capsule and connecting the subthalamic nucleus with the globus pallidus and putamen
• hypothalamus : the ventral part of the diencephalon that forms the floor and part of the lateral wall of the third ventricle. Anatomically, it includes the
• optic tract / tractus opticus : the tract arising from the optic chiasma, proceeding backward, around the cerebral peduncle, and dividing into a lateral and a medial root; the roots end in the cranial colliculus and lateral geniculate body, respectively
• optic chiasm or chiasma / chiasma opticum / optic decussation : the part of the hypothalamus formed by the decussation, or crossing, of the fibers of the optic nerve from the medial half of each retina
• corpus mammillare / mammillary body : either of the pair of small spherical masses situated close together in the interpeduncular space rostral to the posterior perforated substance in the posterior hypothalamic region, consisting of two main nuclei, lateral and medial, and smaller associated aggregations of gray matter. It forms a portion of the limbic system

Tracts :
• mammillopeduncular tract : a fiber tract from the mammillary body to nuclei in the interpeduncular fossa.
• fasciculus mammillotegmentalis / mammillotegmental fasciculus / mammillotegmental tract : a bundle of fibers from the mammillary body to the tegmental nuclei of the reticular formation of the mesencephalon
• fasciculus mammillothalamicus / mammillothalamic fasciculus / mammillothalamic tract / thalamomammillary bundle / thalamomammillary fasciculus : a stout bundle of fibers from the mammillary body to the anterior nucleus of the thalamus
• tuberculum trigeminale / trigeminal tubercle / tuberculum cinereum / gray tubercle / tubercle of Rolando / tuber cinereum : an elevation in the caudal part of the posterior surface of the medulla oblongata located between the fasciculus cuneatus and the roots of the accessory nerve, produced by the descending spinal tract of the trigeminal nerve and the caudal (inferior) cerebellar peduncle
• panting  or polypneic center : a center in the tuber cinereum that accelerates the rate of breathing.
• infundibulum :
• neurohypophysis (considered a distinct structure for physiological purposes)
The hypothalamus may be divided into 5 regions or areas ... :
• area or regio hypothalamica dorsalis / dorsal hypothalamic area or region : the most dorsal part of the hypothalamus, comprising the entopeduncular nucleus and the nucleus of the ansa lenticularis
• area or regio hypothalamica intermedia / intermediate hypothalamic area or region : the part of the hypothalamus comprising the lateral hypothalamic region and the following nuclei: arcuate, tuberal, ventromedial hypothalamic, dorsomedial hypothalamic, dorsal hypothalamic, posterior periventricular, and infundibular
• area or regio hypothalamica lateralis / lateral hypothalamic area or region : a part of the intermediate hypothalamic area lateral to the fornix and the mammillothalamic fasciculus
• area or regio hypothalamica posterior / posterior hypothalamic area or region : the most posterior part of the hypothalamus, consisting of the lateral and medial nuclei of the mammillary body and the posterior hypothalamic nucleus
• area or regio hypothalamica rostralis / anterior hypothalamic area or region / preoptic area or region : the most anterior part of the hypothalamus, lying adjacent to the lamina terminalis and superior to the optic chiasm, and comprising the lateral and medial preoptic nuclei, the supraoptic and paraventricular nuclei; and the anterior hypothalamic nucleus
... or into 3 longitudinal zones :
• lateral zone of hypothalamus : containing part of the preoptic nuclei as well as the supraoptic and tuberal nuclei and the nuclei of the mammillary body
• medial zone of hypothalamus : containing part of the preoptic nuclei as well as the anterior, dorsomedial, and ventromedial hypothalamic nuclei.
• periventricular zone : containing part of the preoptic nuclei as well as the periventricular, infundibular, and posterior nuclei.
• periventricular system : collective name for the efferent pathways of the hypothalamus that arise mainly in the supraoptic, posterior, and tuberal nuclei and descend in the periventricular gray substance
The hypothalamic nuclei constitute that part of the corticodiencephalic mechanism that activates, controls and integrates the peripheral autonomic mechanisms, endocrine activity, and many somatic functions, e.g., a general regulation of water balance, body temperature, sleep, and food intake, and the development of secondary sex characteristics.
• thermoregulatory centers : hypothalamic centers regulating the conservation and dissipation of heat
• sudorific center : a center in the anterior hypothalamus controlling diaphoresis.
• thirst center : a group of cells in the lateral hypothalamus that when stimulated cause a sensation of thirst
• satiety center : a group of cells in the ventromedial hypothalamus that when stimulated suppress the desire for food.
• feeding or hunger center : a group of cells in the lateral hypothalamus that when stimulated cause a sensation of hunger.
The hypothalamus secretes vasopressin and oxytocin, which are stored in the pituitary, as well as many releasing factors (hypophysiotropic hormones), by means of which it exerts control over functions of the adenohypophysis.
• hypothalamic sulcus / sulcus hypothalamicus [Monroi] : a shallow curved sulcus on the wall of the third ventricle, extending from the interventricular foramen to the cerebral aqueduct.
• nucleus anterior hypothalami / anterior hypothalamic nucleus : a nucleus of nerve cells in the anterior hypothalamic region
• nucleus arcuatus hypothalami / arcuate nucleus of hypothalamus / infundibular nucleus / nucleus infundibularis / nucleus semilunaris : a nucleus of nerve cells in the posterior hypothalamic region, extending into the median eminence and almost entirely surrounding the base of the infundibulum
• nucleus dorsalis hypothalami / dorsal hypothalamic nucleus : a nerve cell nucleus situated in the dorsal portion of the intermediate hypothalamic region.
• nucleus dorsomedialis hypothalamicae intermediae / dorsomedial nucleus of intermediate hypothalamus : a group of nerve cell bodies found in the dorsal part of the intermediate hypothalamic region.
• nucleus endopeduncularis / endopeduncular nucleus : a small nucleus in the internal capsule of the hypothalamus adjacent to the medial edge of the globus pallidus.
• suprachiasmatic nucleus / nucleus suprachiasmaticus : a small nucleus in the supraoptic region of the hypothalamus, just above the optic chiasm; it influences rhythmical aspects of hypothalamic functions in many vertebrate species, including humans.
• nucleus supraopticus / supraoptic nucleus : a sharply defined nucleus of nerve cells in the anterior hypothalamic region, immediately above the lateral part of the optic chiasm; many of its cells are neurosecretory in function, secreting antidiuretic hormone, which is carried to the posterior lobe of the pituitary gland by the fibers of the supraopticohypophysial tract; other cells are osmoreceptors which respond to increased osmotic pressure to signal the release of antidiuretic hormone by the posterior lobe of the pituitary gland
• nucleus paraventricularis hypothalami / paraventricular nucleus of hypothalamus : a sharply defined band of cells in the wall of the third ventricle in the anterior hypothalamic region; many of its cells are neurosecretory in function, secreting oxytocin, which is carried to the posterior lobe of the pituitary gland by the fibers of the paraventriculohypophysial tract.
• nuclei tuberales laterales / lateral tuberal nuclei : nerve cell nuclei situated ventrally in the intermediate hypothalamic region, mainly in the lateral hypothalamic area.
• nucleus ventromedialis hypothalami / ventromedial hypothalamic nucleus / ventrolateral hypothalamic nucleus / ventromedial or ventrolateral nucleus of hypothalamus : a group of nerve cell bodies found in the ventral portion of the intermediate hypothalamic region; it is involved in diverse functions, e.g., food intake and sexual behavior
• sex-behavior center
Tracts :
• fasciculus medialis telencephali / medial forebrain bundle / fasciculus prosencephalicus medialis / medial prosencephalic fasciculus / medial telencephalic fasciculus : a fiber system that is the main pathway for longitudinal connection in the hypothalamus; it runs through the lateral hypothalamic region, connecting the tegmentum of the mesencephalon and elements of the limbic system
• fibrae periventriculares / periventricular fibers : fibers that arise from the hypothalamus, then descend in the central gray matter through the tegmentum of the mesencephalon and the reticular formation of the pons and medulla oblongata; some are found in the dorsal longitudinal fasciculus.
• tractus hypothalamohypophysialis / hypothalamicohypophysial tract / tuberohypophysial tract : the group of nerve fibers making up the efferent pathways of the hypothalamus, arising in the hypothalamic nuclei and ending at various levels in the median eminence, infundibulum, and posterior lobe of the pituitary gland. It contains subgroups of fibers
• tractus supraopticohypophysialis / supraopticohypophysial tract : the group of fibers of the hypothalamicohypophysial tract arising in the supraoptic nucleus of the thalamus; some of the fibers descend to end in the infundibulum and others reach the posterior lobe of the pituitary gland, where their neurosecretory material is stored as antidiuretic hormone before being released into the systemic circulation. The term has also been used to denote the entire set of fibers of the hypothalamicohypophysial tract entering the infundibulum without regard to point of termination and also to denote the parts of the hypothalamicohypophysial tract that arise in the supraoptic nucleus and the paraventricular nucleus
• fibrae supraopticae / fibrae supraopticohypophysiales / supraoptic fibers : the efferent fiber components of the hypothalamicohypophysial tract that arise in the supraoptic nucleus and form the supraopticohypophysial tract.
• tractus paraventriculohypophysialis / paraventriculohypophysial tract : the part of the hypothalamicohypophysial tract that arises in the paraventricular nucleus of the hypothalamus; some of the fibers end in the infundibulum and others reach the posterior lobe of the pituitary gland, where their neurosecretory material is stored as oxytocin before being released into the systemic circulation.
• fibrae paraventriculares / fibrae paraventriculohypophysiales / paraventricular fibers : the efferent fiber components of the hypothalamicohypophysial tract that arise in the paraventricular nucleus and form the paraventriculohypophysial tract.
• pretectal area or region / area pretectalis : an area at the junction of the mesencephalon and diencephalon, extending from a position dorsolateral to the commissure of the epithalamus toward the cranial colliculus, within which is situated the pretectal nucleus
• brainstem / brain stem / truncus encephalicus : the stalklike portion of the brain connecting the cerebral hemispheres with the spinal cord and comprising the mesencephalon, pons, and medulla oblongata; the diencephalon is considered part of the brain stem by some
• centrencephalic system : the system of neurons located in the central core of the upper brain stem from the thalamus down to the medulla oblongata, and connecting the 2 hemispheres of the brain
• formatio reticularis / reticular formation : any of several diffuse networks of cells and fibers in the spinal cord and brainstem; subdivided into
• formatio reticularis tegmenti mesencephali / reticular formation of mesencephalon / formatio reticularis mesencephali
• formatio reticularis tegmenti pontis / reticular formation of pons / formatio reticularis pontis
• formatio reticularis medullae oblongatae
• formatio reticularis spinalis / spinal reticular formation / reticular formation of spinal cord / formatio reticularis medullae spinalis
Functions :
• lateral parvocellular reticular formation (integrative functions)
• medial magnocellular reticular formation (projecting functions)
• ascending system (to cortex) : thalamic nuclei with diffuse projections
• intralaminar nuclei of thalamus
• medial central (MC) nucleus of thalamus
• central lateral (CL) nucleus of thalamus
• median nuclei of thalamus
=>
• activating mesencephalic reticular system (if injured => coma)
• deactivating pontine-bulbar reticular system (=> sleep; if injured => insomnia)
... stimulate and inhibit cerebral cortex.
• descending system (to spinal cord)
• modulating pregangliar neurons of ANS
• vasomotor or cardiovascular control centers : centers in the medulla oblongata and the lower pons that regulate the caliber of the blood vessels and increase or decrease the heart rate and contractility
• vasoconstrictor center
• vasodilator center which inhibits the former via GABAergic neurons
• cardioaccelerating or accelerating center : the part of the vasomotor center involved in acceleration of the heart
• Kronecker's cardioinhibitory center : the part of the vasomotor center that exerts an inhibitory influence on the heart by way of the vagus
• respiratory centers : a series of centers in the medulla oblongata and pons which coordinate respiratory movements; they include
• pneumotaxic center / Lumsden's center
• apneustic center : the neurons in the brain stem that control normal respiration; not a true center
• medullary respiratory center
The normal breathing rhythm in mammals is hypothesized to be generated by NK₁-expressing neurons in the preBötzinger complex (preBötC), a medullary region proposed to contain the kernel of the circuits generating respiration. If this hypothesis is correct, then complete destruction of preBötC NK1R neurons should severely perturb and perhaps even fatally arrest breathing. Specific and near complete bilateral (but not unilateral) destruction of preBötC NK1R neurons results in both an ataxic breathing pattern with markedly altered blood gases and pH, and pathological responses to challenges such as hyperoxia, hypoxia and anesthesia. Thus, these 600 neurons seem necessary for the generation of normal breathing in rats^ref.
• modulating lower motoneurons or radicular cells :
• pontine reticulospinal tract
• bulbar reticulospinal tract
Nuclei reticulares / reticular nuclei : nuclei found in the reticular formation of the brainstem, occurring primarily in longitudinal columns in 3 groups. The term also encompasses several other nuclei that are not in any of the 3 columns, e.g., the nucleus reticularis thalami.
• medial column reticular nuclei : 2 groups of reticular nuclei of the brainstem, located symmetrically in the central parts of the two halves of the tegmentum; their neurons are often large, with long axons, and have dendrites and preterminal axons at right angles to the long axis of the brainstem. Included are the
• nucleus gigantocellularis
• nucleus reticularis tegmenti pontis
• nucleus reticularis pontis caudalis
• nucleus reticularis pontis rostralis
• nucleus cuneiformis
• nucleus subcuneiformis
• median column reticular nuclei / nuclei raphes / raphe nuclei : found in narrow longitudinal sheets along the raphae of the medulla oblongata, pons, and mesencephalon; they include many neurons that synthesize serotonin. Their ascending fibers project to parts of the limbic system and their descending fibers project to other brain stem nuclei, the medulla oblongata, and the pons. In the group are
• nucleus raphes magnus
• nucleus raphes obscurus
• nucleus raphes pallidus
• nucleus raphes pontis
• nucleus raphes posterior
• nucleus raphes medianus
• nucleus linearis inferioris
• nucleus linearis intermedius
• nucleus linearis superior
• lateral column reticular nuclei : a pair of symmetrical groups of scattered small reticular nuclei of the brain stem, each arranged in a column lateral to the medial column reticular nuclei; most of their neurons are associative in nature. Included are
• nucleus reticularis lateralis medullae oblongatae
• nucleus tegmentalis pedunculopontinus
• nucleus reticularis parvocellularis
• nucleus paragigantocellularis lateralis
• nucleus parabrachialis lateralis
• nucleus parabrachialis medialis
• nucleus subparabrachialis
• mesencephalon / midbrain : the part of the brain developed from the middle of the 3 primary vesicles of the embryonic neural tube; it comprises the
• tegmentum mesencephali or mesencephalicum / tegmentum of mesencephalon or of midbrain : the posterior part of the mesencephalon, formed by continuation of the posterior parts of the cerebral peduncles across the median plane, and extending on each side from the substantia nigra to the level of the mesencephalic aqueduct
• midtegmentum : the median or central part of the tegmentum
Nuclei :
• formatio reticularis tegmenti mesencephali / reticular formation of mesencephalon / formatio reticularis mesencephali : the part of the mesencephalon that has a reticular structure like that of the medulla oblongata; it lies between the substantia nigra and the central gray matter
• nucleus commissurae posterioris / nucleus of posterior commissure : a nucleus of the rostral midbrain tegmentum, located adjacent to the posterior commissure and near the oculomotor nucleus
• nuclei tegmenti / nuclei of tegmentum
• nuclei tegmentales anteriores / anterior or ventral tegmental nuclei : several masses of neurons of the mesencephalic tegmentum, situated ventral to the medial longitudinal fasciculus
• nucleus tegmentalis pedunculopontinus / tegmental pedunculopontine nucleus : a nucleus at the posterior end of the mesencephalon, sometimes considered one of the lateral column reticular nuclei. It merges anteriorly into the cuneiform and subcuneiform nuclei.
• nucleus tegmentalis posterolateralis / laterodorsal or lateroposterior tegmental nucleus : a nucleus of nerve cells in the mesencephalic tegmentum, situated dorsal to the nucleus of the trochlear nerve
• nucleus nervi oculomotorii / nucleus of oculomotor nerve : a nuclear complex that is the origin of the fibers of the oculomotor nerve, situated in the tegmentum of the mesencephalon immediately ventral to the central gray matter, between the medial longitudinal fasciculi. The complex comprises larger paired dorsolateral and ventromedial somatic groups
• nucleus dorsalis nervi oculomotorii / dorsal nucleus of oculomotor nerve / nucleus of oculomotor nerve : a group of dorsally placed cells in the lateral part; they are distinct from the ventrally placed cells in the middle third of the complex and have a somatic motor function
• nucleus anteromedialis nervi oculomotorii / anterior or ventral medial or ventromedial nucleus of oculomotor nerve : ventrally placed cells in the lateral part ; they are distinct from the dorsally placed cells in the middle third of the complex and have a somatic motor function
 ... as well as scattered small nuclei that have a parasympathetic function :
• nuclei accessorii nervi oculomotorii / accessory nuclei of oculomotor nerve / Edinger-Westphal nuclei / nuclei oculomotorii accessorii or autonomici : a collection of small cells located dorsal to the upper part of the somatic groups, comprising the parasympathetic outflow via the ciliary ganglion to the ciliary muscle and sphincter pupillae of the eye
• nucleus caudalis centralis / central caudal or caudate nucleus : an unpaired collection of cells in the caudal third, located in the median raphe somewhat dorsal to the lateral nuclei
• Siemerling's nucleus
Innervation of the superior rectus of one eye originates in the contralateral oculomotor nerve nucleus; the other elements of the nucleus supply ipsilateral eye muscles via the oculomotor nerve.
Tracts :
• tegmental tract : a tract of fibers in the tegmentum, back of the nucleus posterior corporis trapezoidei, believed to connect the latter with the midbrain
• tractus tegmentalis centralis / central tegmental tract / Bekhterev's tract : a composite nerve tract arising from the midbrain tegmentum, periaqueductal gray matter, and red nucleus; it descends in the tegmentum and reticular formation to end in the inferior olivary complex. The tract includes an ascending component from the reticular formation
• decussatio pedunculorum cerebellarium superiorum / decussation of superior cerebellar peduncles : the crossing of the fibers of the peduncles within the tegmentum of the mesencephalon.
• decussationes tegmentales, tegmenti or tegmentorum / tegmental decussations : crossing fibers in the midbrain, including the decussatio tegmentalis anterior and the decussatio tegmentalis posterior.
• decussatio tegmentalis anterior / anterior tegmental decussation : the anterior portion of the decussation of the cerebellar peduncle, comprising fibers of the lateral third of the peduncle, which decussate immediately dorsal to the interpeduncular nucleus in the ventral tegmentum. The fibers merge with those of the decussatio tegmentalis posterior at the level of the caudal red nucleus.
• decussatio tegmentalis posterior / posterior tegmental decussation : the posterior portion of the decussation of the cerebellar peduncle, comprising fibers of the medial two-thirds of the peduncle, which start to cross the midline at the level of the inferior colliculus, ventral to the medial longitudinal fasciculus. The fibers merge with those of the decussatio tegmentalis anterior at the level of the caudal red nucleus.
• tectum mesencephali, mesencephalicum / tectum of mesencephalon or of midbrain / mesencephalic tectum : that part of the mesencephalic tegmentum comprising the tectal lamina and the inferior and superior colliculi.
• corpora bigemina : 2 bodies in the brain of the human fetus that later split to become the corpora quadrigemina.
• corpora quadrigemina : the rostral and caudal colliculi of the tectum of the mesencephalon considered together.
• lamina tectalis mesencephali / lamina tecti mesencephali / tectal plate / lamina quadrigemina / quadrigeminal plate : the layer of mingled gray and white substance in the tectum of the mesencephalon, from which arise 2 pars of rounded eminences symmetrically located..
• colliculus superior / rostral or superior colliculus : the superior (rostral) pair, containing reflex centers for visual sensations
• commissura colliculi rostralis or superioris / commissura colliculi  / commissure of rostral or superior colliculus : a band of nerve fibers that connect the 2 superior colliculi
Tracts :
• testobulbar tract : a bundle of fibers arising mostly in the cranial colliculus; it descends to the lower border of the pons where it ends in the nuclei of the brain stem and in the reticular formation.
• tractus tectobulbaris / tectobulbar tract : a bundle of fibers arising mostly in the superior colliculus; it descends to the lower border of the pons where it ends in the nuclei of the brain stem and in the reticular formation
• tractus tectospinalis / tectospinal tract : a group of nerve fibers, chiefly crossed, which arise mostly in the cranial colliculus and descend to the cervical cord, where they lie in the ventral funiculus
• medial tectospinal tract
• lateral tectospinal tract
• colliculus inferior / caudal or inferior colliculus : the inferior (caudal) pair, containing reflex centers for auditory sensations
• nuclei colliculi caudalis / nuclei colliculi inferioris / nuclei of inferior colliculus / nuclei of caudal colliculus / nuclei colliculi caudalis : the large oval-shaped group of nerve cells that make up most of the substance of the inferior colliculus
• commissura colliculi inferioris / commissure of inferior colliculus / commissura colliculi caudalis and commissure of caudal colliculus : a band of nerve fibers that connect the two inferior colliculi
Tracts :
• transverse peduncular tract :  a small band of fibers which passes from the brachium of the inferior colliculus to the sulcus medialis cruris cerebri.
Nuclei :
• nucleus commissurae posterioris / nucleus of posterior commissure : a nucleus of the rostral midbrain tegmentum, located adjacent to the posterior commissure and near the oculomotor nucleus.
Tracts :
• tectocerebellar tract : a bundle of fibers from the tectum of the mesencephalon to the cerebellum
• fasciculus sulcomarginalis / sulcomarginal fasciculus : a layer of descending branches from the midbrain tectum situated in the ventral funiculus of the spinal cord, along the border of the ventral median fissure
• cerebral peduncles / pedunculus cerebralis / pedunculus cerebri / peduncle of cerebrum : either of the 2 large masses of substance that descend from each cerebral hemisphere, being separated by the interpeduncular fossa until they converge where they enter the pons; they form the ventral part of the mesencephalon. Each peduncle is divided into an anterior part, consisting of a bundle of nerve fiber tracts (basis pedunculi cerebri), and a posterior part, which is continuous across the median plane, forming the tegmentum of the mesencephalon; the parts are separated by the substantia nigra. The term also has been used to denote the right or left half of the midbrain, each consisting of an anterior part, the crus cerebri, and a posterior or tegmental part, the tegmentum
• sulcus nervi oculomotorii / oculomotor sulcus / sulcus oculomotorius / medial sulcus of crus cerebri / medial sulcus of mesencephalon : a longitudinal groove on the medial surface of the anterior part of the cerebral peduncle that lodges the oculomotor nerve
• subthalamic tegmentum : the portion of the tegmentum of the cerebral peduncle extending beneath the thalamus.
• substantia perforata interpeduncularis / substantia perforata posterior / posterior perforated substance / interpeduncular perforated substance : the floor of the interpeduncular fossa, between the cerebral peduncles, which is pierced by central branches of the posterior cerebral artery
• locus caeruleus, ceruleus, cinereus or coeruleus : a pigmented eminence in the superior angle of the floor of the brain
• nucleus caeruleus / nucleus ceruleus / nucleus coeruleus : a compact aggregation of pigmented neurons subjacent to the locus caeruleus; it is sometimes considered one of the medial reticular nuclei. At its upper end it connects with the mesencephalic nucleus of the trigeminal nerve
• nucleus subcaeruleus / nucleus subceruleus : a group of neurons subjacent to the nucleus caeruleus in the anterior part of the pons; sometimes considered part of the medial column reticular nuclei.
• nuclei campi perizonalis / nuclei of perizonal field : the group of nuclei in the ventral thalamus comprising the nucleus of the prerubral field (field H of Forel) and neurons scattered along the thalamic and lenticular fasciculi in fields H1 and H2 of Forel.
• nucleus campi dorsalis / nucleus of dorsal field : the group of nerve cell bodies among the fibers of field H₁ of Forel
• nucleus campi medialis / nucleus of medial field / nucleus of prerubral field / nucleus of tegmental field : any of the groups of neurons scattered along the caudomedial border of the zona incerta in field H of Forel (prerubral field)
• nucleus campi ventralis / nucleus of ventral field : the group of nerve cell bodies among the fibers of field H₂ of Forel
• nucleus cuneiformis / nucleus cuneiformis mesencephalicus / cuneiform nucleus : a large nucleus in the mesencephalon representing a widening and continuation of the tracts from the medial column reticular nuclei.
• nucleus subcuneiformis / subcuneiform nucleus : a nucleus in the mesencephalon adjacent to and closely associated with the cuneiform nucleus.
• nucleus linearis inferioris / inferior linear nucleus : a raphe nucleus located in the mesencephalon.
• nucleus linearis intermedius / intermediate linear nucleus : a raphe nucleus located in the mesencephalon.
• nucleus linearis superior / superior linear nucleus : a raphe nucleus located in the mesencephalon.
• Darkshevich's nucleus : a small nucleus dorsal to the medial longitudinal fasciculus in the central gray matter at the rostral end of the cerebral aqueduct; it is believed to receive fibers from the fasciculus and from the superior colliculus.
• nucleus ruber / red nucleus : a distinctive oval nucleus (pink in fresh specimens because of an iron-containing pigment in many of the cells) centrally placed in the upper mesencephalic reticular formation; it receives fibers from the deep cerebellar nuclei and cerebral cortex and projects fibers to the cerebellum, brain stem, spinal cord, and probably to the thalamus
• pars magnocellularis nuclei rubri / magnocellular part of red nucleus : in humans, the posterior part of the red nucleus, containing a complement of large multipolar cells; the number of these cells is relatively decreased in comparison to the small cells scattered throughout the nucleus
• pars parvocellularis nuclei rubri / parvocellular part of red nucleus : the complement of small multipolar cells scattered throughout the red nucleus; in humans, these cells predominate over the large cells in the caudal part of the nucleus
Tracts :
• rubroreticular tract : a group of fibers extending from the red nucleus to the reticular formation of the pons and medulla oblongata.
• tractus rubrospinalis / rubrospinal tract / Monakow's bundle, fasciculus, or tract : a group of nerve fibers in the lateral funiculus of the spinal cord, arising in the large cells of the red nucleus of the mesencephalon
• tractus rubrobulbaris / rubrobulbar tract : a group of nerve fibers arising in the red nucleus and terminating at several different parts of the brain stem including the nucleus of the facial nerve, the motor nucleus of the trigeminal nerve, and the inferior olivary nucleus.
• sulcus lateralis mesencephali / lateral sulcus of mesencephalon / lateral sulcus of crus cerebri : a longitudinal groove on the side of the mesencephalon, separating the crus cerebri from the tegmentum
• crus cerebri / pars anterior pedunculi cerebri / anterior part of cerebral peduncle : the part anterior to the substantia nigra, consisting of a large bundle of nerve fiber tracts called the basis pedunculi cerebri
• substantia grisea centralis or periaqueductalis / central, periaqueductal or periventricular gray substance : diffuse collections of small cells immediately surrounding the ependymal lining of the third ventricle of the brain, around the cerebral aqueduct, and in the floor of the fourth ventricle
• fasciculus longitudinalis dorsalis or posterior / dorsal or posterior longitudinal fasciculus / Schütz's bundle or tract : a lightly myelinated fiber bundle that runs in the periventricular gray substance throughout the extent of the mesencephalon, near the medial longitudinal fasciculus, driving conjugate eyeball movements
• aqueduct of mesencephalon
• substantia nigra (SN) / black substance : the layer of gray substance that separates the posterior parts of the cerebral peduncles (tegmentum mesencephali) from the anterior parts; it includes
• pars reticularis substantiae nigrae / reticular part of substantia nigra (SNpr) : the anterior part of the substantia nigra, which contains fewer cells than the pars compacta, only some of which contain a small amount of pigment
• pars compacta substantiae nigrae / compact part of substantia nigra (SNpc) : the posterior part of the substantia nigra, medium-sized cells, many of which are pigmented.
• nucleus nervi trochlearis / nucleus of trochlear nerve / nucleus trochlearis / trochlear nucleus : the nucleus of origin of the motor fibers of the trochlear nerve; it lies in the central gray matter on the dorsal surface of the medial longitudinal fasciculus in the lower part of the mesencephalon
• nucleus mesencephalicus nervi trigemini / nucleus mesencephalicus trigeminalis / mesencephalic nucleus of trigeminal nerve / nucleus tractus mesencephalici nervi trigeminalis : one of the nuclei of the trigeminal nerve, consisting of a slender column of cells in the lateral central gray matter of the superior part of the fourth ventral and cerebral aqueduct. It is the only CNS site of primary sensory neurons; its cells resemble posterior root ganglion cells. The peripheral processes of the cells, which form the mesencephalic tract, carry proprioceptive impulses; the central processes have widespread cerebellar and brain stem connections, including the motor nucleus of the trigeminal nerve
• pontopeduncular sulcus : the sulcus that separates the pons from the mesencephalon (as represented by the cerebral peduncles).
• pons (cerebelli) : the part of the CNS lying between the medulla oblongata and the mesencephalon, superior to the cerebellum
• pars anterior, basilaris or ventralis pontis / basilar part of pons : the part of the pons connecting the cerebrum, cerebellum, and medulla oblongata. It is a broad transverse band that arches across the anterior surface of the superior end of the rhombencephalon; on each side it narrows to enter the cerebellum as the middle cerebellar peduncle. It comprises longitudinal fibers originating at the cerebral cortex, transverse fibers, and the pontine nuclei
• tegmentum pontis / tegmentum of pons / pars dorsalis or posterior pontis / tegmentum rhombencephali : the posterior part of the pons, which resembles the medulla oblongata in structure and is continuous with the tegmentum of the mesencephalon
• basilar sulcus of pons / sulcus basilaris pontis : the anteromedian groove in the pons, lodging the basilar artery.
• bulbopontine or medullopontine sulcus / sulcus bulbopontinus : a transverse groove in front and on each side of the pons that demarcates it from the medulla oblongata, which is occupied by the abducent, facial, and vestibulocochlear nerves
Nuclei :
• formatio reticularis tegmenti pontis / reticular formation of pons / formatio reticularis pontis : the part of the pars dorsalis pontis, anterior to the central gray matter, that has a structure similar to that of the reticular formation of the medulla oblongata
• pontine reticular nuclei : any of the reticular nuclei located in the pons.
• nucleus reticularis pontis caudalis / caudal pontine reticular nucleus / nucleus reticularis intermedius pontis inferioris / inferior intermediate pontine reticular nucleus : a medial column reticular nucleus in the pons, located next to the nucleus reticularis tegmenti pontis and superior to the gigantocellular nucleus
• nucleus reticularis pontis oralis / nucleus reticularis pontis rostralis / oral pontine reticular nucleus / nucleus reticularis intermedius pontis superioris / superior intermediate pontine reticular nucleus : either of a symmetrical pair of medial column reticular nuclei in the central part of the pons, one on either side of the superior central nucleus
• nucleus reticularis tegmentalis pontinus / nucleus reticularis tegmenti pontis / tegmental pontine reticular nucleus / reticulotegmental nucleus : either of a pair of medial column reticular nuclei located symmetrically in the posterior part of the pons between the nucleus raphes pontis and the nucleus reticularis pontis caudalis
• subparabrachial nucleus / nucleus subparabrachialis / Kölliker-Fuse nucleus : either of a pair of parabrachial nuclei that constitute part of the lateral column reticular nuclei; it is a pneumotaxic center lying ventral to the medial and lateral parabrachial nuclei in the pons
• nucleus parabrachialis lateralis / lateral parabrachial nucleus : either of a pair of lateral column reticular nuclei located symmetrically on the border between the pons and the mesencephalon, adjacent to the brachium of the caudal colliculus and lateral to the cuneiform and subcuneiform nuclei
• nucleus parabrachialis medialis / medial parabrachial nucleus : either of a pair of lateral column reticular nuclei located symmetrically in the pons, near the caudal border of the mesencephalon, lateral to the nucleus reticularis pontis rostralis and nucleus reticularis pontis caudalis.
• nucleus raphes medianus / median raphe nucleus / superior central nucleus : a raphe nucleus in the anterior part of the pons; its neurons are serotoninergic
• nucleus raphes pontis / pontine raphe nucleus : a raphe nucleus in the central part of the pons; its neurons are serotoninergic
• nucleus raphes posterior / posterior raphe nucleus / dorsal raphe nucleus / nucleus raphes dorsalis : a large raphe nucleus extending from the anterior part of the pons through the mesencephalon; its neurons are serotoninergic
• nucleus salivatorius superior / superior salivatory nucleus / superior salivary nucleus / nucleus salivarius superior : an ill-defined column of scattered cells in the posterolateral part of the reticular formation of the posterior pons, continuous with the inferior salivatory nucleus; its cells comprise the parasympathetic outflow of the facial nerve for the supply of the lacrimal, nasal, palatine, submandibular, and sublingual glands
• principal sensory nucleus of trigeminal nerve / nucleus principalis nervi trigemini / pontine nucleus of trigeminal nerve / nucleus pontinus nervi trigeminalis / nucleus sensorius principalis nervi trigeminalis : the nucleus of termination of afferent fibers of the trigeminal nerve, carrying impulses for sensations of touch and pressure, located in the dorsolateral part of the middle of the pons, just lateral to the entering trigeminal root fibers
• nucleus motorius nervi trigemini / motor nucleus of trigeminal nerve : the nucleus of origin of the motor fibers of the trigeminal nerve, located in the dorsolateral part of the pons, just medial to the main sensory nucleus and the entering sensory root. Each one is innervated by bilateral corticonuclear fibers.
• nucleus nervi abducentis / nucleus of abducens nerve / abducens nucleus / nucleus abducens / nucleus abducentis : the nucleus of origin of the abducens nerve; it lies in the lower part of the pons and forms the lateral part of the facial colliculus in the floor of the fourth ventricle; fibers of the facial nerve form a complicated loop about the nucleus
• nucleus nervi facialis / nucleus facialis / motor nucleus of facial nerve / nucleus of facial nerve : the nucleus of origin of the motor fibers of the facial nerve, which innervate the muscles of facial expression; the nucleus lies in the ventrolateral part of the lower pons, and its emerging fibers form a complicated loop about the nucleus of the abducens nerve
• pneumotaxic center / Lumsden's center : a center in the upper part of the pons that rhythmically inhibits inspiration independently of the vagi
Tracts :
• tractus pontoreticulospinalis / pontoreticulospinal tract / medial reticulospinal tract : a group of reticulospinal nerve fibers in the lateral funiculus of the spinal cord, arising in the pontobulbar region
• corpus trapezoideum / trapezoid body : a mass of transverse fibers extending through the central part of the pons and forming a part of the path of the cochlear nerve.
• nuclei of trapezoid body : a group of nerve cell bodies of the superior olivary complex, lying within the fibers of the trapezoid body
• fibrae pontis longitudinales / longitudinal pontine fibers : a group of longitudinal nerve fibers that arise in the crus cerebri and run to the ventral part of the pons, where they become dispersed into smaller bundles, separated by the nuclei of the pons and the transverse fibers of the pons. The group includes the corticospinal, corticonuclear, corticoreticular, and corticopontine fibers.
• fibrae pontis transversae / transverse pontine fibers : fibers within the ventral part of the pons which arise from the pontine nuclei and run laterally to form the middle cerebellar peduncles. Most of these fibers cross the midline. They are part of the frontopontocerebellar pathway.
• fibrae pontis profundae : the more deeply situated of the fibrae pontis transversae.
• fibrae pontis superficiales : the more superficial of the fibrae pontis transversae.
• fibrae pontocerebellares / pontocerebellar fibers : longitudinal fibers in the ventral part of the pons that terminate in the vermis of the cerebellum.
• medulla oblongata / myelencephalon / bulb / bulbus encephali : the truncated cone of nerve tissue continuous above with the pons and below with the spinal cord. It lies anterior to the cerebellum, and the upper part of its posterior surface forms the floor of the lower part of the fourth ventricle; it contains ascending and descending tracts, and important collections of nerve cells that deal with vital functions, such as respiration, circulation, and special senses
• foramen caecum medullae oblongatae / foramen caecum posterius / Schwalbe's foramen / foramen of Vicq d'Azyr : a small triangular expansion at the lower border of the pons, formed by the termination of the anterior median fissure of the medulla oblongata
• tuberculum cuneatum / cuneate tubercle : an enlargement of the fasciculus cuneatus in the medulla oblongata, just lateral to the tuberculum gracile, produced by the underlying nucleus cuneatus.
• tuberculum gracile / gracile tubercle : an enlargement of the nucleus gracilis in the medulla oblongata, forming the lower lateral border of the posterior part of the fourth ventricle, produced by the underlying nucleus gracilis
• lemniscus medialis / medial or sensory lemniscus : a tract arising from the internal arcuate fibers of the nuclei gracilis and cuneatus, and crossing to the opposite side in the lower part of medulla oblongata to ascend, first between the 2 olives, and then through the pars dorsalis pontis just dorsal to the pontine nuclei; it continues through the tegmentum of the midbrain and ends in the ventral posterior part of the thalamus. Each lemniscus carries sensory impulses from the opposite side of the body
• pyramis bulbi or medullae oblongatae / pyramid of medulla oblongata  : either of 2 rounded masses, one on either side of the anterior median fissure of the medulla oblongata, composed of motor fibers (pyramidal tract) from the cerebral cortex to the spinal cord and medulla oblongata
• sulcus retroolivaris / retroolivary groove : a groove running longitudinally across the posterolateral surface of the upper medulla oblongata just behind the olive; it is the forward continuation of the sulcus posterolateralis medullae oblongatae.
• sulcus anterolateralis or ventrolateralis medullae oblongatae / anterolateral or ventrolateral sulcus or groove of medulla oblongata : a longitudinal sulcus on the anterior surface of the medulla oblongata, lateral to the pyramid, from which emerge the fibers of the hypoglossal nerve
• fissura mediana anterior medullae oblongatae / anterior median fissure of medulla oblongata / anteromedian groove of medulla oblongata / fissura mediana ventralis medullae oblongatae : the longitudinal fissure in the median plane of the anterior aspect of the medulla oblongata, continuous with the anterior median fissure of the spinal cord; it separates the pyramids and is partially obliterated below by their decussation
• sulcus medianus posterior medullae oblongatae / posterior median sulcus of medulla oblongata / dorsal or posterior median fissure of medulla oblongata / dorsal median sulcus of medulla oblongata / sulcus medianus dorsalis medullae oblongatae : a narrow groove present only in the closed part of the medulla oblongata, separating the two fasciculi graciles; it is the continuation of the posterior median sulcus of the spinal cord
• sulcus posterolateralis medullae oblongatae / posterolateral sulcus of medulla oblongata / posterolateral groove of medulla oblongata / dorsolateral sulcus of medulla oblongata / sulcus dorsolateralis medullae oblongatae : an upward extension of the posterolateral sulcus of the spinal cord; it gives attachment to the fibers of the glossopharyngeal, vagus, and accessory nerves
• area retroolivaris / retroolivary area : the most caudal part of the lateral region of the medulla oblongata, towards the posterolateral sulcus
• sulcus limitans fossae rhomboideae / sulcus limitans of rhomboid fossa : a longitudinal groove on the lateral side of the medial eminence, extending the entire length of the floor of the fourth ventricle.
• sulcus limitans ventriculorum cerebri / sulcus limitans of cerebral ventricles : a groove midway on the inner surface of each lateral wall of the neural tube, which separates it into a dorsal, alar plate and a ventral, basal plate.
Nuclei :
• nuclei nervi vagi / nuclei of vagus nerve : the nuclei of origin and termination of the vagus nerve, situated in the medulla oblongata, comprising the
• nucleus posterior nervi vagi / posterior nucleus of vagus nerve / dorsal vagal nucleus / dorsal nucleus of vagus nerve / nucleus alae cinereae / nucleus vagalis dorsalis / nucleus dorsalis nervi vagi : the nucleus of origin of the parasympathetic fibers of the vagus nerve, situated in the trigone of the vagus nerve in the floor of the fourth ventricle, lateral to the nucleus of the hypoglossal nerve
• nucleus ambiguus
• nuclei tractus solitarii
• nucleus commissuralis nervi vagi / commissural nucleus of vagus nerve : a group of noradrenergic neurons that encloses the dorsolateral aspect of the nucleus of the hypoglossal nerve and approaches the ependymal floor of the fourth ventricle.
• retrofacial nucleus / nucleus retrofacialis : a small nucleus between the nucleus ambiguus and the facial nucleus, believed to be a source of vagal efferent visceral fibers.
• nucleus nervi glossopharyngei / nucleus of glossopharyngeal nerve : the nucleus of origin and termination of the glossopharyngeal nerve, located in the medulla oblongata, comprising
• rostral part of the nucleus ambiguus
• nuclei tractus solitarii
• nucleus salivarius or salivatorius inferior / inferior salivatory or salivary nucleus : the inferior part of the column of scattered cells in the posterolateral part of the reticular formation in the lower pons and upper medulla oblongata; they comprise the parasympathetic outflow of the glossopharyngeal nerve for the supply of the parotid gland
• nucleus ambiguus / ambiguous nucleus : the nucleus of origin of motor fibers of the vagus, glossopharyngeal, and accessory nerves that supply the striated muscles of the larynx and pharynx. It consists of an intermittent cell column in the middle of the lateral funiculus of the medulla oblongata, between the caudal end of the medulla and the level of exit of the glossopharyngeal nerve.
• nuclei tractus solitarii (NTS) / nuclei of solitary tract / solitary nuclei / nuclei solitarii : any of various nuclei of termination of the visceral afferent fibers of the facial, glossopharyngeal, and vagus nerves, which enter the tractus solitarius. The nuclei surround the tractus solitarius and their caudal ends join with the caudal ends of the corresponding nuclei of the opposite side
• nucleus nervi hypoglossi / nucleus of hypoglossal nerve / hypoglossal nucleus / nucleus hypoglossalis : the nucleus of origin of the hypoglossal nerve, forming a column in the central gray matter of the medial eminence from below the level of the inferior olive to the upper part of the medulla oblongata
• sublingual nucleus / Roller's nucleus : a sharply defined nucleus immediately ventral to the nucleus of the hypoglossal nerve, forming part of the perihypoglossal nuclear complex
• nucleus retroambiguus / retroambiguus nucleus : a nucleus near the nucleus ambiguus, with motor fibers that control both inspiratory and expiratory muscles.
• nucleus reticularis lateralis medullae oblongatae / lateral reticular nucleus : either of a symmetrical pair of lateral column reticular nuclei, each in a lateral funiculus of the medulla oblongata adjacent to a nucleus ambiguus.
• nucleus reticularis paramedianus / paramedian reticular nucleus : a small nucleus in the ventromedial medulla oblongata near the nucleus of the hypoglossal nerve.
• nucleus reticularis parvocellularis / parvocellular reticular nucleus : either of a pair of principal lateral column reticular nuclei, lying lateral to the nucleus gigantocellularis and adjacent to the nucleus ambiguus.
• nucleus arcuatus medullae oblongatae / arcuate nucleus of medulla oblongata : one of the group of small, irregular areas of gray substance found on the ventromedial aspect of the pyramid of the medulla oblongata.
• vestibulocochlear nuclei / nuclei of vestibulocochlear nerve : the vestibular and cochlear nuclei considered together
• nuclei cochleares / cochlear nuclei / nuclei of cochlear nerve / nuclei nervi cochlearis : the 2 nuclei, anterior and posterior, partly encircling the inferior cerebellar peduncle (lentiform body) at the junction of the medulla oblongata and the pons, in which the fibers of the cochlear part of the vestibulocochlear nerve terminate
• nucleus cochlearis anterior or cochlearis / anterior or ventral cochlear nucleus : located on the anterolateral aspect of the inferior cerebellar peduncle; it receives the larger, ascending branches of the cochlear nerve
• nucleus cochlearis dorsalis or posterior / posterior or dorsal cochlear nucleus : located on the dorsal aspect of the inferior cerebellar peduncle; it forms an eminence (the auditory tubercle) on the lateral part of the vestibular area of the floor of the fourth ventricle
• nuclei vestibulares / vestibular or acoustic nuclei / nuclei of acoustic nerve / nuclei nervi vestibularis : the 4 cellular masses in the lateral floor of the fourth ventricle in which the short ascending and longer descending branches of the pars vestibularis nervi octavi terminate and in which cerebellar projections are received. The nuclei give rise to a widely dispersed special sensory system through projections to motor nuclei in the brain stem and cervical cord via the medial longitudinal fasciculi from all the vestibular nuclei to the cerebellum (chiefly from the inferior and medial nuclei), and to motor cells throughout the spinal cord (from the lateral nucleus). Additional connections of the nuclei provide for conscious perception of, and autonomic reactions to, labyrinthine stimulation
• nucleus vestibularis inferior / inferior vestibular nucleus : a vestibular nucleus that lies lateral to the middle nucleus and medial to the inferior cerebellar peduncle.
• nucleus vestibularis lateralis / lateral vestibular nucleus / Deiters' nucleus / large cell auditory nucleus : a vestibular nucleus composed of large multipolar nerve cells that lies immediately superior to the inferior vestibular nucleus; its upper end becomes continuous with the superior vestibular nucleus
• nucleus vestibularis medialis / medial vestibular nucleus / triangular nucleus / nucleus triangularis / Schwalbe's nucleus : a vestibular nucleus that lies in the floor of the fourth ventricle and extends upward from the medulla oblongata and pons
• nucleus vestibularis rostralis / nucleus vestibularis superior / superior vestibular nucleus / Bekhterev's nucleus / cranial or rostral vestibular nucleus : a small vestibular nucleus that lies above the lateral vestibular nucleus
Tracts : fasciculus longitudinalis medialis (FLM) / medial longitudinal fasciculus : a fiber tract extending in the mesencephalon, pons (fasciculus longitudinalis medialis pontis), bulb (fasciculus longitudinalis medialis medullae oblongatae) and the upper part of the spinal cord; it lies close to the median plane, just ventral to the central gray matter, and interconnects the vestibular nuclei with motor nuclei, chiefly those of the oculomotor (III) nerve, trochlear (IV), abducens (VI) nerve, and accessory (XI) nerve cranial nerves.
• nucleus cuneatus / cuneate nucleus : a nucleus in the medulla oblongata at the rostral end of the fasciculus cuneatus, in which the fibers of this fasciculus synapse; the cells project to the thalamus via the medial lemniscus

Tracts :
• fasciculus cuneatus medullae oblongatae / cuneate fasciculus of medulla oblongata : the continuation into the medulla oblongata of the fasciculus cuneatus of the spinal cord
• nucleus cuneatus accessorius / accessory cuneate nucleus / lateral cuneate nucleus : a group of nerve cells lying lateral to the nucleus cuneatus that relay impulses from upper limb fibers in the fasciculus cuneatus to the cerebellum (rostral spinocerebellar tract) via external arcuate fibers and the inferior cerebellar peduncle
• funiculus cuneatus lateralis : a longitudinal ridge on the medulla oblongata between the line of roots of the spinal accessory nerve and the fasciculus cuneatus.
• nucleus gracilis / gracile nucleus / nucleus of Goll's column : a nucleus in the medulla oblongata at the rostral end of the fasciculus gracilis of the cord, in which the fibers of the fasciculus gracilis synapse; the cells project to the thalamus via the medial lemniscus

Tracts :
• fasciculus gracilis medullae oblongatae / posteromedian column of medulla oblongata : the continuation into the medulla oblongata of the fasciculus gracilis of the spinal cord
• gigantocellular nucleus / nucleus gigantocellularis / gigantocellular intermediate reticular nucleus / gigantocellular reticular nucleus : either of a symmetrical pair of large medial column reticular nuclei located in the superior part of the medulla oblongata and the posterior part of the pons, lateral to the nucleus raphes magnus and inferior to the caudal pontine reticular nucleus; its neurons are serotoninergic
• lateral paragigantocellular nucleus / nucleus paragigantocellularis lateralis : either of a pair of lateral column reticular nuclei located symmetrically at the level of the facial nucleus, rostral to the nucleus retroambiguus
• nucleus raphes magnus / magnus raphe nucleus : a raphe nucleus partially overlapping the nucleus pallidus and nucleus obscurus in the medulla oblongata and projecting upward into the posterior part of the pons; its neurons are serotoninergic.
• nucleus raphes obscurus / obscurus raphe nucleus : a raphe nucleus of the medulla oblongata closely associated with the nucleus pallidus raphes; its neurons are serotoninergic.
• nucleus raphes pallidus / pallidal raphe nucleus : a raphe nucleus of the medulla oblongata closely associated with the nucleus raphes obscurus; its neurons are serotoninergic.
• nucleus olivaris rostralis / nucleus olivaris superior / superior olivary nucleus / superior olivary complex / nucleus olivaris cranialis / cranial or rostral olivary nucleus : a band of gray substance located laterally at the level of the pontomedullary junction superior to the inferior olivary nucleus; its fibers form the olivocochlear tract
• coughing center : a center in the medulla oblongata, situated above the respiratory center, which controls the act of coughing.
• deglutition center : a nerve center in the medulla oblongata that controls the function of swallowing
• vomiting center : a center in the lower central region of the medulla oblongata receiving fibers from the chemoreceptor trigger zone (CTZ); its stimulation causes vomiting.
• sudorific center : any of several centers in the medulla oblongata or spinal cord that exercise parasympathetic control over diaphoresis
• vasoconstrictor center : a center in the medulla oblongata and lower pons that controls contraction of the blood vessels
• vasodilator center : a center in the medulla oblongata that causes dilation of blood vessels by repressing the activity of the vasoconstrictor center.
• medullary respiratory center : the part of the respiratory centers that is in the medulla oblongata, divided between
• dorsal respiratory group : part of the medullary respiratory center running the length of the medulla oblongata, largely within the nucleus of the solitary tract; its main function is to control the basic rhythm of respiration
• ventral respiratory group : part of the medullary respiratory center running the length of the medulla oblongata within and next to the nucleus ambiguus; these neurons mainly function during strong, active respiration, moving voluntary muscles in the control of inspiration and expiration or modifying the behavior of other respiratory motoneurons
• oliva / olive / inferior olive / olivary body / olivary nucleus : a rounded elevation, lateral to the upper part of each pyramid of the medulla oblongata, between the ventrolateral and dorsolateral sulci; it is formed by an irregular mass of gray substance (nucleus olivaris caudalis) located just beneath its surface and is linked by fiber systems to the pons and cerebellum
• complexus olivaris inferior / inferior olivary complex / nuclei olivares inferiores / inferior olivary nuclei / nuclei olivares caudales / caudal olivary nuclei : a folded band of gray matter that encloses a white core (hilum nuclei olivaris inferioris) and that produces the elevation called the oliva on the medulla oblongata. It is a nuclear complex that receives heavy projections from the spinal cord, mesencephalon, and cerebral cortex and projects fibers via the contralateral inferior cerebellar peduncle, mostly to the neocerebellum, with a few going to the vermis
• Roller's nucleus : cells near the hilum of the inferior olivary nucleus.
• vellus olivae : a narrow band of tangential fibers surrounding the olive.
Tracts :
• tractus olivocerebellaris / olivocerebellar tract : a fiber tract that arises from the olive, crosses to the opposite side to pierce the other olive, and enters the cerebellum through inferior cerebellar peduncles
• tractus olivocochlearis / olivocochlear tract or fasciculus : a group of fibers derived from the nucleus of the superior olive that terminates in relation to the hair cells in the spiral organ of the cochlea
• olivospinal tract / Helweg's tract or bundle / triangular tract : a group of nerve fibers in the lateral funiculus, seen as a triangular area in transverse section of the spinal cord; it descends from the olivary nucleus through the medulla oblongata to the upper cervical segments
• formatio reticularis medullae oblongatae : reticular formation of medulla oblongata: the phylogenetically old part of the medulla oblongata which has a reticular structure, i.e., which is structurally composed of diffuse aggregations of nerve cells in the midst of a wealth of nerve fibers and, with certain exceptions, lacks circumscribed cell groups; it fills the spaces between the major nuclei and fiber tracts.
• reticular activating system (RAS) : the system of cells of the reticular formation of the medulla oblongata that receive collaterals from the ascending sensory pathways and project to higher centers; they control the overall degree of CNS activity, including wakefulness, attentiveness, and sleep
Other bulbar tracts : any of the bundles of nerve fibers of the medulla oblongata
• tractus bulboreticulospinalis / bulboreticulospinal tract / lateral reticulospinal tract / medullary reticulospinal tract : a group of reticulospinal nerve fibers in the lateral funiculus of the spinal cord, the axons of which are derived from nerve cells of the medulla oblongata
• Stilling's fibers : nerve fibers in the reticular formation of the medulla oblongata.
• lemniscus lateralis / lateral lemniscus : a tract of longitudinal fibers extending upward through the lateral part of the tegmental substance of the pons, formed chiefly by fibers arising from the opposite cochlear nuclei and the trapezoid body, and ascending to terminate in the inferior colliculus and medial geniculate body.
• tractus solitarius medullae oblongatae / solitary tract of medulla oblongata : a descending tract in the medulla oblongata, ventrolateral to the caudal part of the fourth ventricle, near the dorsal nucleus of the vagus and glossopharyngeal nerves, and comprising primary visceral afferent fibers from the facial, glossopharyngeal, and vagus nerves
• lemniscus trigeminalis / trigeminal lemniscus / tractus trigeminothalamicus / trigeminothalamic tract : a group of fibers conveying sensory impulses from the trigeminal nuclei to the ventral posterior part of the opposite thalamus; it ascends intermingled with the spinal lemniscus and adjacent medial lemniscus
• fibrae arcuatae externae anteriores / anterior external arcuate fibers / ventral external arcuate fibers / fibrae arcuatae externae ventrale : fibers that arise from the arcuate nuclei, emerging from the anterior median fissure; they run laterally, backward, and upward over the medulla oblongata to reach the cerebellum by way of the inferior cerebellar peduncle
• fibrae arcuatae externae posteriores / posterior external arcuate fibers / dorsal external arcuate fibers / fibrae arcuatae externae dorsales : fibers that arise from the accessory cuneate nucleus and enter the cerebellum by way of the ipsilateral inferior cerebellar peduncle
• fibrae arcuatae internae / internal arcuate fibers : fibers that arise from the nucleus cuneatus and nucleus gracilis and pass ventromedially around the central gray substance of the medulla oblongata to form the decussation of the medial lemnisci.
• funiculus lateralis medullae oblongatae / lateral funiculus of medulla oblongata : the continuation into the medulla oblongata of all the fiber tracts of the lateral funiculus of the spinal cord, with the exception of the lateral pyramidal tract.
• decussatio lemnisci medialis / decussation of medial lemniscus : the region at the caudal end of the medulla oblongata in which the fibers from the nucleus cuneatus and the nucleus gracilis on each side intersect as they cross the midline before ascending as the medial lemniscus
• decussatio pyramidum / decussation of pyramids / decussatio motoria / pyramidal decussation / motor decussation : the anterior part of the lower medulla oblongata in which most of the fibers of each pyramid intersect as they cross the midline and descend as the lateral corticospinal tracts
• pedunculi cerebellares / cerebellar peduncles / pedunculi cerebelli : 3 large bundles of projection fibers on each side of the cerebellum that connect it with other parts of the brain and spinal cord
• pedunculus cerebellaris inferior / inferior cerebellar peduncle / pedunculus cerebellaris caudalis / caudal cerebellar peduncle / restiform body : a large bundle of nerve fibers connecting the medulla oblongata and spinal cord with the cerebellum (especially the archeocerebellum and paleocerebellum). It courses along the lateral border of the fourth ventricle and turns posteriorly into the cerebellum. It contains :
• posterior spinocerebellar tract
• olivocerebellar tract
• bulbocerebellar tract
• vestibulocerebellar tract
• pedunculus cerebellaris medius or pontinus / middle or pontine cerebellar peduncle / brachium pontis : a large bundle of projection fibers originating in the contralateral pontine nuclei and entering the cerebellum, conveying impulses from the cerebral cortex to the neocerebellum; it is continuous with the pons at the line of attachment of the trigeminal nerve. It contains :
• frontopontocerebellar tract
• temporopontocerebellar tract
• deep fasciculus of middle cerebellar peduncle : the most dorsal part of the transverse fibers of the pons, connecting pontine nuclei with the folia on the anterior superior surface of the cerebellum.
• inferior fasciculus of middle cerebellar peduncle : the most caudal portion of the transverse fibers of the pons, connecting pontine nuclei with the cerebellar folia near the vermis.
• superior fasciculus of middle cerebellar peduncle : the most rostral portion of the transverse fibers of the pons, connecting pontine nuclei with inferior lobules and posterior and lateral margins of the cerebellum.
• pedunculus cerebellaris rostralis or superior / cranial, rostral or superior cerebellar peduncle : a large bundle of projection fibers arising chiefly in the dentate nucleus of each cerebellar hemisphere (the neocerebellum) and ascending to decussate in the mesencephalon; its fibers end mostly in the red nucleus and thalamus. Spinocerebellar fibers to the palaeocerebellum lie adjacent to each peduncle. It contains :
• anterior spinocerebellar tract
• cerebellorubral tract
• cerebellothalamic tract
• cerebellopontine angle : that between the cerebellum and the pons. It contains :
• trigeminalnerve (V)
• abducens nerve (VI)
• facial nerve (VII)
• acoustic nerve (VIII)
• glossopharyngeal nerve (IX)
• vagus nerve (X)
• accessory nerve (XI)
• anterior inferior cerebellar artery (AICA)
• premeatal portion
• meatal portion
• postmeatal portion
• cerebellum
• hemispherium cerebelli / cerebellar hemisphere : the part of the cerebellum lateral to the vermis
• fissurae cerebelli / cerebellar fissures : the numerous shallow grooves in the cortex of the cerebellum, on the surface and within the deep fissures, which divide the cortex into folia
• cortex cerebelli or cerebellaris / cortex of cerebellum / cerebellar cortex : the superficial gray matter of the cerebellum; it consists of 3 layers
• stratum moleculare or plexiforme cerebelli / molecular or plexiform layer of cerebellum : the superficial layer of the cortex of the cerebellum, containing a relatively small number of stellate neurons, and separated from the granular layer by the Purkinje cell layer
• stratum purkinjense cerebelli / Purkinje cell layer / stratum neuronorum piriformium / piriform neuronal layer : the layer of Purkinje neurons situated between the external molecular layer and the internal granular layer of the cerebellar cortex; considered by some to be the deepest layer of the molecular layer
• stratum granulosum cerebelli / granular layer of cerebellum : the deep layer of the cortex of the cerebellum; it contains many small neurons (granule cells) and is separated from the molecular layer by the Purkinje cell layer.
Cell types :
• basket cell : a cell of the cerebellar cortex whose axon gives off brushes of fibrils, forming a basket-like nest in which the body of each Purkinje cell rests
• climbing, clinging or tendril fibers : afferent fibers arising in part from the middle cerebellar peduncle and passing through the granular layer of the cerebellar cortex to terminate on Purkinje cell dendrites
• moss or mossy fibers : thick afferent nerve fibers arising from the inferior cerebellar peduncle and passing into the cerebellar cortex to terminate in numerous branches or mosslike appendages around the cells of the granular layer
• granule cells : diminutive stellate cells found chiefly in the granular layers
• parallel fibers : axons of granule cells in the cerebellum that cross the molecular layer at a right angle and synapse with gemmules of Purkinje cell dendrite; many thousands of parallel fibers may innervate a single Purkinje cell.
• Purkinje cells : large neurons in the cerebellar cortex that have piriform cell bodies in the Purkinje layer (the stratum purkinjense cerebelli) and large branching dendrite trees going through the outer (molecular) layer towards the surface.
• Bergmann's cells or glia : peculiar glial cells in the molecular layer of the cerebellar cortex having dendrites that extend outward through that layer
• Fañanús' cell / glia of Fañanús : a type of neuroglial cell found in the molecular layer of the cerebellar cortex
• breviradiate cells : neuroglial cells that have short processes
Anatomy :
• folia cerebelli / folia of cerebellum / gyri cerebelli : the numerous long narrow folds of the cerebellar cortex, separated by sulci and supported by white laminae; they are aggregated into the various subdivisions of the cerebellum
• fissurae cerebelli / cerebellar fissures : the numerous shallow grooves in the cortex of the cerebellum, on the surface and within the deep fissures, which divide the cortex into folia
• fissura horizontalis or intercruralis cerebelli / horizontal fissure or sulcus of cerebellum / great horizontal fissure : the fissure that separates the cranial from the caudal semilunar lobule of the cerebellum
• fissura posterolateralis cerebelli / posterolateral fissure of cerebellum / fissura dorsolateralis cerebelli / dorsolateral fissure of cerebellum : the fissure separating the nodulus from the uvula of the vermis and the flocculus from the tonsilla of the cerebellar hemisphere
• fissura prima cerebelli / primary fissure of cerebellum / fissura preclivalis / preclival fissure : the fissure that separates the cranial from the caudal lobe in the cerebellum; it lies between the culmen and declive of the vermis, and between the quadrangular lobule and the lobulus simplex in the hemisphere of the cerebellum
• fissura secunda cerebelli / secondary fissure of cerebellum / fissura postpyramidalis / postpyramidal fissure : a fissure that lies between the uvula of the cerebellum and the pyramid
• postcentral fissure : a fissure separating the central lobule of the cerebellum with its alae from the more dorsal culmen and quadrangular lobules.
• postclival or postlunate fissure / posterior superior fissure : a fissure of the cerebellum between the declive and the folium vermis
• postlingual fissure : a fissure in the anterior part of the superior vermis of the cerebellum, separating the lingula from the central lobule.
• prepyramidal fissure : a fissure between the pyramis vermis and the tuber vermis.
• retrotonsillar fissure : either of a pair of curving fissures in the inferior cerebellum, lateral continuations of the sulcus valleculae, between the tonsils and the biventral lobes
Phylogenesis :
• neocerebellum : the phylogenetically newest part of the cerebellum, described as corresponding to the lateral parts of the cerebellum, including
• corpus cerebelli / body of cerebellum : the main portion of the cerebellum, consisting of
• the 2 cerebellar hemispheres
• middle portion of the vermis
Because the hemispheres are the primary site of termination of the projections from the pons, the corticopontocerebellar fibers, the term is sometimes equated with pontocerebellum
• archicerebellum / archaeocerebellum / archeocerebellum : the phylogenetically oldest part of the cerebellum; namely, the flocculonodular lobe. Because this lobe is the site of termination of most of the projections of vestibular afferents, the term is sometimes equated with vestibulocerebellum
• lobus flocculonodularis / flocculonodular lobe : a fundamental subdivision of the cerebellum, located inferiorly, consisting of paired lateral flocculi, their pedunculi, and the nodulus
• pedunculus flocculi / peduncle of flocculus : a narrow band of afferent and efferent nerve fibers that connects the nodulus of the cerebellum to the flocculus; its dorsal part is continuous with the anterolateral part of the caudal medullary velum, from which most of its fibers are derived
• paleocerebellum : the phylogenetically second oldest part of the cerebellum, namely the vermis of the anterior lobe and the pyramis, uvula, and paraflocculus of the posterior lobe. Because this corresponds roughly to the primary site of termination of the major spinocerebellar afferents, the term is sometimes equated with spinocerebellum
• lobus cerebelli anterior, cranialis or rostralis / anterior, cranial or rostral lobe of cerebellum : the portion of the cerebellum lying in front of the primary fissure, comprising the
• lingula cerebelli / lingula of cerebellum : the most ventral part of the anterior lobe of the cerebellum, where the superior medullary velum attaches
• lobulus centralis cerebelli / central lobule of cerebellum : the portion of the anterior lobe of the cerebellum between the lingula and the culmen, resting on the lingula and the anterior medullary velum
• alae of central lobules :
• culmen cerebelli / culmen of cerebellum : the portion of the rostral lobe of the cerebellum that lies medially between the central lobule and the primary fissure
• lobus cerebelli caudalis or posterior / posterior, caudal or middle lobe of cerebellum : the portion of the cerebellum separated from the anterior lobe by the primary fissure and from the flocculonodular lobe by the dorsolateral fissure; it comprises the
• vermis cerebelli / vermis of cerebellum : the narrow median part of the cerebellum, between the two lateral hemispheres; the cranial or superior portion extends from the lingula to the folium vermis, and the inferior or caudal portion from the tuber vermis to the nodulus.
• folium vermis : the part of the vermis of the cerebellum between the declive and the tuber vermis
• pyramis vermis / pyramid of vermis : the part of the vermis of the cerebellum between the tuber vermis and the uvula
• tuber vermis / tuber of vermis : the part of the vermis of the cerebellum between the folium vermis and the pyramids.
• uvula vermis / uvula of vermis or of cerebellum : the part of the vermis of the cerebellum between the pyramis and the nodulus
• sulcus valleculae : a groove in the inferior cerebellum that separates the uvula vermis from the tonsils.
• lobulus simplex cerebelli / simple lobule of cerebellum : the large anterior division of the posterior cerebellar lobe, comprising
• lobulus quadrangularis anterior cerebelli / anterior quadrangular lobule of cerebellum : the portion of the cranial lobe of the hemisphere of the cerebellum lying between the postcentral and primary fissures, continuous with the culmen.
• declive (monticuli cerebelli) / clivus monticuli : the part of the vermis of the cerebellum just caudal to the primary fissure
• lobuli semilunares / semilunar lobules / lobulus ansiformis : the lobulus semilunaris inferior and lobulus semilunaris superior considered together
• lobulus semilunaris caudalis / lobulus semilunaris inferior / inferior semilunar lobule / caudal semilunar lobule / crus secundum lobuli ansiformis : that portion of the posterior lobe of the cerebellum that is continuous with the tuber vermis
• lobulus semilunaris rostralis / lobulus semilunaris superior / cranial or rostral semilunar lobule / crus primum lobuli ansiformi / superior semilunar lobule : that part of the cerebellar hemisphere that is continuous with the folium vermis
• paraflocculus / accessory flocculus : a small lobe of the cerebellar hemisphere, located immediately cranial to the flocculus and sometimes forming a prominent part of the cerebellum
• tonsilla cerebelli / tonsilla of cerebellum / ventral paraflocculus / paraflocculus ventralis : a rounded mass forming part of the caudal lobe of the hemisphere of the cerebellum continuous with the uvula of the vermis
• lobulus biventer / biventral lobule : the part of the posterior lobe of the cerebellum that is between the tonsilla and the inferior semilunar lobule
• lobulus gracilis cerebelli / gracile lobule of cerebellum / lobule paramedianus cerebelli / paramedian lobule : the portion of the posterior lobe of the hemisphere of the cerebellum between the lobulus simplex and the semilunar and biventral lobules
• lobulus quadrangularis posterior cerebelli / posterior quadrangular lobule of cerebellum : the portion of the posterior lobe of the hemisphere of the cerebellum continuous with the declive.
• corpus medullare cerebelli / medullary body of cerebellum : the white substance of the cerebellum; called also medullary center of cerebellum.
• nuclei cerebellares / nuclei cerebelli / cerebellar nuclei / intracerebellar nuclei and roof nuclei : 4 accumulations of gray substance embedded in the white substance of the cerebellum, comprising...
• roof nuclei : a term sometimes used to refer to the nuclei cerebelli because some of them are situated in close proximity to the roof of the fourth ventricle of the brain.
• interpositus nucleus
• nucleus interpositus anterior / nucleus emboliformis : the term is preferred in official terminology when considering nonprimate mammals, and is occasionally used to refer to primates.
• nucleus interpositus posterior / nucleus globosus : the term is preferred in official terminology when considering nonprimate mammals, and is occasionally used to refer to primates.
• nucleus dentatus / dentate nucleus : the largest of the cerebellar nuclei, lying in the white matter of the cerebellum just lateral to the emboliform nucleus, and receiving Purkinje cell fibers from the neocerebellum; its axons form most of the superior cerebellar peduncles and project chiefly to the contralateral red nucleus and thalamus. It is the term preferred in official terminology when considering humans, and is frequently also used to describe nonhuman primates.
• Voit's nucleus : a cerebellar nucleus accessory to the dentate nucleus
• fibrae dentatorubrales / dentatorubral fibers : afferent nerve fibers received by the red nucleus from the contralateral dentate nucleus.
• nucleus fastigii / fastigial nucleus : the most medial of the cerebellar nuclei, near the midline in the roof of the fourth ventricle; it projects to the pons and medulla oblongata, chiefly to the vestibular nuclei. It is the term preferred in official terminology when considering humans, and is frequently also used to describe nonhuman primates
• nucleus medialis cerebelli / nucleus fastigii :  the term is preferred in official terminology when considering nonprimate mammals, and is occasionally used to refer to primates.
• juxtarestiform body : a structure connecting the lateral vestibular nucleus with the nucleus fastigii and conveying vestibular impulses.
Tracts :
• cerebellorubral tract : a group of fibers arising chiefly in the dentate nucleus of the cerebellum and projecting to the opposite red nucleus via the superior cerebellar peduncles; impulses are then relayed to the reticular formation and spinal cord.
• cerebellorubrospinal tract : a group of fibers that passes from one dentate nucleus of the cerebellum to the contralateral red nucleus, and thence to the spinal cord.
• cerebellospinal tract : uncinate fasciculus of the cerebellum, from the fastigial nucleus to the cervical cord.
• cerebellothalamic or dentatothalamic tract : a group of fibers arising chiefly in the dentate nucleus of the cerebellum and projecting to the ventral lateral nucleus of the opposite thalamus via the superior cerebellar peduncles; impulses are then relayed to the frontal lobe
The encephalon contains 150 mL of blood : see also arterial circle of Willis
• medulla spinalis / spinal cord : that part of the CNS that is lodged in the neurocanal / canalis vertebralis / vertebral canal (the cervical spinal cord lies on the anterior wall or rachid, while the lumbar one lies on the posterior wall). It extends from the foramen magnum (where it is continuous with the medulla oblongata), to the upper part of the lumbar region (ending between T12 and L3, often at or near L1 and L2 due to lifting during vertebral canal development). It is composed of an inner core of gray substance, in which nerve cells predominate, and an outer layer of white substance, in which myelinated nerve fibers predominate, and is enclosed in meninges. 31 spinal nerves originate from the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. It conducts impulses to and from the brain, and controls many automatic muscular activities (reflexes)
• columna vertebralis / axon / backbone / spine / vertebral, dorsal, or spinal column : the columnar assemblage of the vertebrae from the cranium through the coccyx (26) :
• cranial vertebrae :  the segments of the skull and facial bones, by some regarded as modified vertebrae
• vertebra : any of the 33 bones of the spinal column (columna vertebralis), comprising the 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal vertebrae.
• corpus vertebrae / corpus vertebrale / vertebral body : the body of a vertebra, consisting of the centrum, the ossified neurocentral joint and part of the vertebral arches, and the facets for the heads of the ribs
• fasciculi longitudinales ligamenti cruciformis atlantis / longitudinal fasciculi of cruciform ligament : vertical midline longitudinal fibers that, together with the transverse ligament of the atlas, form the cruciform ligament of the atlas. The fibers arise in two groups from the root of the dens—one group extending cranially to the anterior margin of the foramen magnum, the other caudally to the body of the axis.
• arcus vertebrae / arcus vertebralis / arch of vertebra / neural arch of vertebra / vertebral arch : the bony arch on the dorsal aspect of a vertebra, composed anteriorly of a pair of pedicles and posteriorly of a pair of laminae
• lamina arcus vertebrae / lamina of the vertebral arch : either of the pair of broad plates of bone flaring out from the pedicles of the vertebral arches and fusing together at the midline to complete the dorsal part of the arch and provide a base for the spinous process.
• foramen vertebrale / vertebral foramen / medullary foramen / spinal foramen or aperture : the large opening in a vertebra formed by its body and arch
• processus spinosus vertebrae / spinous process of vertebra : a part of the vertebra projecting backward from the arch, giving attachment to muscles of the back.
• processus transversus vertebrae / transverse process of vertebra : a process on either side of a vertebra, projecting laterally from the junction between the lamina and the pedicle.
• sulcus nervi spinalis / sulcus for spinal nerve : the groove onthe upper surface of each transverse process of a cervical vertebra, extending from the foramen transversarium lateralward and separating the anterior and posterior tubercles. It lodges the ventral branch of a cervical nerve
• foramen intervertebrale / intervertebral foramen : the passage formed by the inferior and superior notches on the pedicles of adjacent vertebrae; it transmits a spinal nerve and vessels.
• processus articularis superior vertebrae / superior articular process of vertebra / zygapophysis superior : a process on either side of a vertebra, springing from the superior surface of the arch near the junction of the lamina and pedicle; it bears a surface that faces posteriorly and superiorly, articulating with the inferior articular process of the vertebra above
• processus articularis inferior vertebrae / inferior articular process of vertebra / zygapophysis inferior : a process on either side of a vertebra, springing from the inferior surface of the arch near the junction of the lamina and pedicle; it bears a surface that faces anteriorly and inferiorly, articulating with the superior articular process of the vertebra below
• true vertebrae : the vertebrae that normally remain unfused throughout life
• cervical vertebrae / vertebrae cervicales (C1 through C7) extend from the neck to the thorax. Except for C7 (vertebra prominens) that has a long unifid spinous process, all typical cervical vertebrae have a short bifid spinous process. These vertebrae show a hole in their spinous processes called foramen transversarium. These foramina transmit the vertebral arteries. C7’s foramina transversaria are however smaller and only transmit small accessory vertebral veins. These vertebrae also show anterior and posterior tubercles at their transverse processes’ extremity. C7’s anterior tubercle is however vestigial and very small. Grooves (x2) for the exit of the spinal nerves (x2) associated with the vertebra are also present on the superior aspect of the transverse processes. Cervical spinal nerves thus course just above pedicles on their way to exit above their corresponding vertebra contrarily to the pattern respected in the rest of the cord. This is because there is a C8 spinal nerve but no corresponding C8 vertebra: this nerve thus exits between C7 and T1.
• atlas (C1) has no true body. Most of it has been incorporated on the axis as the dens. Part of it remains on the atlas as its anterior arch. Neither the atlas possesses any spinous process. A small posterior tubercle replaces it at the extremity of the posterior arch. Lateral masses bear kidney-shaped articular facets for the occipital condyles on their superior aspect and oval-shaped articular facets on their inferior aspect for articulation with the superior articular facets of the axis. The posterior aspect of the anterior arch bears an articular facet for the dens of the axis and its anterior aspect bears the anterior tubercle. The lateral masses bear a tubercle on their medial aspect for the attachment of the transverse ligament of the atlas. The transverse processes of the atlas show foramina transversaria and the superior aspect of its posterior arch shows a groove on each side in which the vertebral arteries course. The vertebral arteries enter the vertebral canal as such and ascend through the foramen magnum to eventually join and form the basilar artery.


• tuberculum anterius atlantis / anterior tubercle of atlas : the conical eminence on the front of the anterior arch of the atlas.
• axis (C2) / epistropheus / odontoid vertebra / vertebra dentata


• typical cervical vertebrae


• uncus corporis vertebrae cervicalis / uncus of body of cervical vertebra / uncinate process of cervical vertebra : a hooklike projection found on each side of the superior surface of the C3 to C7 vertebral bodies. This is a frequent site of formation of spurs (osteophytes), leading to spondylosis uncovertebralis
• tuberculum anterius vertebrae cervicalis / anterior tubercle of cervical vertebra : a tubercle on the anterior part of the extremity of each transverse process, lying lateral to the posterior tubercle and at a slightly higher level in all except the sixth vertebra, to which are attached the scalenus anterior, longus capitis, and longus colli muscles.
• vertebra prominens / prominent vertebra : the C7 vertebra, so called because of the length of its spinous process, although it is only the spine that is prominent. (NOTE: the spinous process of T1 is often more prominent.)
• foramen transversarium / transverse foramen / foramen processus transversi / foramen of transverse process / foramen vertebroarteriale / vertebroarterial foramen : the passage in either process of a cervical vertebra that, in C1 to C6, transmits the vertebral vessels; it is small or may be absent in C7
• vertebrae thoracales / vertebrae thoracicae / thoracic vertebrae : the vertebrae, usually 12 in number (symbols T1 through T12), situated between the cervical and the lumbar vertebrae, giving attachment to the ribs and forming part of the posterior wall of the thorax
• vertebrae lumbales / lumbar vertebrae : the 5 vertebrae between the thoracic vertebrae and the sacrum. Lumbar vertebral bodies are larger than thoracic ones. Lumbar vertebrae have 4 additional processes :
• processus accessorius / accessory process : a small nodule that projects backward from the posterior surface of the transverse process and lateral to and below the mammillary process of a lumbar vertebra. Such a process also occurs on the tenth, eleventh, and twelfth thoracic vertebrae.
• processus mammillaris / mammillary process : a tubercle on each superior articular process of the lumbar vertebrae (L1 to L5) and on the T10, T11, T12 vertebrae
• processus costiformis / costal process / processus costalis : a process that projects laterally from the transverse process of a lumbar vertebra and resembles a rib. Lumbar vertebrae have no costal facets since there is no ribs at the lumbar level
• Hartigan's foramen : a foramen said to exist in the base of the transverse process of a lumbar vertebra but seldom persisting to adult life.
• basilar vertebra : the lowest or last of the lumbar vertebrae
• false vertebrae : the vertebrae that become fused
• sacrum (S1) forms the posterior wall of the pelvis.
• foramina intervertebralia ossis sacri / intervertebral foramina of sacrum / intersacral canals or foramina : the 4 short, forked tunnels in each lateral wall of the sacral canal, connecting it with the pelvic and dorsal sacral foramina
• foramina sacralia anteriora / anterior sacral foramina / internal or ventral sacral foramina / foramina sacralia pelvica / foramina sacralia pelvina / foramina sacralia ventralia : the 8 openings (four on each side) on the pelvic surface of the sacral bone for the ventral rami of the sacral nerves
• foramina sacralia posteriora / posterior sacral foramina / dorsal sacral foramina / foramina sacralia dorsalia : the 8 openings (four on each side) on the dorsal surface of the sacral bone for the dorsal rami of the sacral nerves
• sacral cornu / cornu sacrale / sacral horn / coccygeal eminence : either of the two hook-shaped processes extending downward from the arch of the last sacral vertebra
• hiatus sacralis / sacral hiatus : the opening at the inferior end of the sacral canal formed by failure of the laminae of the fifth and sometimes the fourth sacral vertebrae to meet in the midline.
• hiatus intermedius lumbosacralis : a cleft in the region of the first sacral vertebra, considered to represent a normally delayed ossification in young subjects
• hiatus lumbosacralis : the gap between the arches of the fifth lumbar and first sacral vertebrae, which is greater than the space between any vertebrae at a higher level
• coccyx (1) is one mass of 4 to five 5 coccygeal vertebrae that have fused into one commonly called the "tailbone."
• cornu coccygeum / cornu coccyx / coccygeal horn / cornu coccygeale: either of the cranial pair of rudimentary articular processes of the coccyx that articulate with the cornua of the sacrum
Physiological spine curves :
• kyphosis : humpback curving posteriorward
• dorsal or thoracic kyphosis
• lordosis : humpback curving anteriorward
• cervical lordosis
• lumbar lordosis
• ligamenta flava / yellow, arcuate or flaval ligaments : a series of bands of yellow elastic tissue attached to and extending between the ventral portions of the laminae of two adjacent vertebrae, from the junction of the axis and the third cervical vertebra to the junction of the fifth lumbar vertebra and the sacrum. They assist in maintaining or regaining the erect position and serve to close in the spaces between the arches
• ligamentum longitudinale anterius / anterior longitudinal ligament : a single long, fibrous band in the midline, attached to the ventral surfaces of the bodies of the vertebrae; it extends from the occipital bone and the anterior tubercle of the atlas down to the sacrum.
• ligamentum longitudinale posterius / posterior longitudinal ligament : a single midline fibrous band attached to the dorsal surfaces of the bodies of the vertebrae, extending from the occipital bone to the coccyx.
• vertebral groove : the depression on each side of the spine between the spinous processes, laminae, and transverse processes; it lodges the deep back muscles
Cell types :
• endogenous fibers : nerve fibers of the spinal cord which arise from cells the bodies of which are situated inside the cord.
• exogenous fibers : fibers of the spinal cord which arise from cells the bodies of which are situated outside the cord.
• Clarke's cells : pigmented cells in the thoracic column of the spinal cord
• hecatomeral cells : cells of gray matter of the spinal cord whose axis cylinder processes divide and send one branch into the white substance of the same side of the cord and another into the anterolateral columns of the other side
• Renshaw cells : interneurons in the ventromedial region of the spinal cord that make inhibitory connections with the motoneurons
• Rohon-Beard cells : giant ganglion cells in the spinal cord of some vertebrates
• tautomeral cells : cells of the gray matter of the spinal cord whose axons pass into the white substance of the same side of the cord
• segments => 31 pairs of spinal nerves
• intrasegmental fibers : fibers in the white commissures of the spinal cord that link neurons to contralateral neurons at the same level.
• intersegmental fibers
Anatomy :
• neutral zone of His : a thickening of the dorsal portion of the embryonic spinal cord projecting into the central canal.
• dorsal zone of His : the smaller upper thickening of the dorsal portion of the embryonic spinal cord projecting into the central canal.
• fissura mediana anterior or ventralis medullae spinalis / anterior median fissure of spinal cord / anteromedian groove of spinal cord / Haller's line / sulcus ventralis medullae spinalis : the deep longitudinal fissure in the median plane of the anterior aspect of the spinal cord; it contains the anterior spinal artery ensheathed in the linea splendens
• sulcus anterolateralis or ventrolateralis medullae spinalis / anterolateral or ventrolateral sulcus of spinal cord / anterolateral groove of spinal cord : the longitudinal groove on the anterolateral surface of the spinal cord, from which the anterior nerve roots emerge; it separates the anterior and lateral funiculi
• sulcus medianus dorsalis or posterior medullae spinalis / dorsal or posterior median sulcus of spinal cord / dorsal or posterior median fissure of spinal cord : a shallow vertical groove on the posterior median surface of the spinal cord, separating the two posterior funiculi; the posterior median septum extends out from it
• sulcus intermedius dorsalis or posterior medullae spinalis / dorsal or posterior intermediate sulcus of spinal cord : a longitudinal sulcus in the cervical and upper thoracic parts of the spinal cord between the fasciculus gracilis and the fasciculus cuneatus
• sulcus dorsolateralis or posterolateralis medullae spinalis / dorsolateral or posterolateral groove or sulcus of spinal cord : a longitudinal sulcus on the posterolateral surface of the spinal cord; it gives entrance to the posterior nerve roots and separates the lateral and posterior funiculi
• commissura alba medullae spinalis / white commissure of spinal cord
• commissura alba anterior medullae spinalis / anterior or ventral white commissure of spinal cord : the aggregate of fibers crossing from one side of the spinal cord to the other, anterior to the gray commissure
• commissura alba posterior medullae spinalis / posterior or dorsal white commissure of spinal cord : the group of transverse myelinated nerve fibers crossing from one side of the spinal cord to the other posterior to the central canal, permeating the gray commissure
• substantia alba medullae spinalis : the white substance of the spinal cord, consisting of long myelinated nerve fibers arranged in parallel longitudinal bundles.
• funiculi medullae spinalis / funiculi of spinal cord : the large bundles of fiber tracts that make up the white substance of the spinal cord.
• funiculus dorsalis or posterior medullae spinalis / dorsal or posterior funiculus of spinal cord : the white substance of the spinal cord lying on either side between the posterior median sulcus and the posterior roots of the spinal nerves
• fasciculus proprius posterior medullae spinalis / dorsal or posterior fasciculus proprius of spinal cord / dorsal or posterior intersegmental fasciculus or tract of spinal cord : any of the bundles of white substance in the deepest part of the posterior funiculus of the spinal cord, consisting chiefly of intersegmental fibers derived from the cells of the posterior gray column, which divide into ascending and descending association fibers that reenter the gray substance and ramify in it
• septomarginal fasciculus / fasciculus septomarginalis / septomarginal tract : a bundle of nerve fibers situated along the dorsal periphery of the dorsal funiculus of the spinal cord in the thoracic region and bordering the dorsal median septum in the lumbar region
• funiculus lateralis medullae spinalis / lateral funiculus of spinal cord / anterolateral column : the white substance of the spinal cord that lies on either side between the dorsal and ventral roots of the spinal nerves
• fasciculus proprius lateralis medullae spinalis / lateral fasciculus proprius of spinal cord / lateral intersegmental fasciculus of spinal cord / lateral intersegmental tract of spinal cord : any of the bundles of white substance in the lateral funiculus of the spinal cord, consisting of intersegmental fibers, some of which have passed from the contralateral side, and probably reticulospinal and autonomic fibers
• funiculus anterior or ventralis medullae spinalis / lateral or ventral funiculus of spinal cord
• fasciculus proprius anterior medullae spinalis / anterior fasciculus proprius of spinal cord / anterior or ventral intersegmental fasciculus of spinal cord / ventral fasciculus proprius of spinal cord / anterior or ventral intersegmental tract of spinal cord : any of the bundles of white substance in the anterior funiculus of the spinal cord, consisting of intersegmental fibers, some of which pass from the contralateral side, and probably also reticulospinal and descending autonomic fibers
• fiber tracts of spinal cord : distinct bundles in the white substance of the spinal cord, made up of fibers which have the same origin, termination, and function.


• ascending tract : any bundle of nerve fibers that conveys impulses toward the brain (spino-)
• tractus posterolateralis / posterolateral tract / dorsolateral fasciculus or tract / Lissauer's marginal zone : a group of nerve fibers in the lateral funiculus of the spinal cord dorsal to the dorsal column, composed in part of primary pain and temperature fibers which enter the spinal cord, travel the distance of a few segments in the dorsolateral tract, and then synapse in the dorsal column
• fasciculus gracilis medullae spinalis / column of Goll : the median portion of the posterior funiculus of the spinal cord, composed of ascending fibers that terminate in the nucleus gracilis of the medulla oblongata
• fasciculus interfascicularis / interfascicular fasciculus / comma tract of Schultze / fasciculus semilunaris / Schultze's tract / semilunar fasciculus or tract : a collection of fibers situated between the fasciculus gracilis and the fasciculus cuneatus, containing some of the descending branches of the fibers of the medial division of the posterior roots of the spinal nerves
• fasciculus cuneatus medullae spinalis / cuneate fasciculus of spinal cord / cuneate fasciculus of Burdach : the lateral portion of the posterior funiculus of the spinal cord, composed of ascending fibers that terminate in the nucleus cuneatus of the medulla oblongata
• cornuradicular zone : the outer part of the fasciculus cuneatus medullae spinalis.
• tractus spinoreticularis / spinoreticular tract : an ascending tract of nerve fibers in the lateral funiculus of the spinal cord, passing to the reticular formation of the brain stem.
• tractus spinotectalis / spinotectal tract : a group of nerve fibers in the lateral funiculus of the spinal cord, mostly crossed from their origin, which ascend to the superior and inferior colliculi and carry somatic sensory impulses.
• tractus spinoolivaris / spinoolivary tract : an ascending tract of nerve fibers in the lateral funiculus of the spinal cord, arising from the posterior gray columns of the spinal cord and running to the olivary nucleus.
• tractus spinocervicalis / spinocervical tract : a somatosensory pathway consisting of fibers that pass out of the posterior spinocerebellar tract, pass through the lateral cervical nucleus, and ascend with the medial lemniscus to the nucleus ventralis posterolateralis (VP_l) of the thalamus.
• spinocervicothalamic tract : a tract ascending uncrossed in the posterior part of the lateral funiculus to the lateral cervical nucleus, which relays to the thalamus by way of the opposite medial lemniscus.
• spinothalamic tract
• lemniscus spinalis / spinal lemniscus / tractus anterolaterales / anterolateral tracts / anterolateral system : the part of each spinothalamic tract within the pons and mesencephalon, forming a diffuse bundle between the medial and lateral lemnisci. It carries pain, temperature, and tactile impulses from the opposite side of the body and ends in the ventral posterior part of the thalamus
• tractus spinothalamicus anterior or ventralis / anterior or ventral spinothalamic tract / neospinothalamic tract : a group of nerve fibers in the anterior funiculus of the spinal cord, continuous with the spinothalamic tract; they arise in the contralateral gray substance and ascend to the thalamus, joining the medial lemniscus in the brain stem. They carry sensory impulses activated by light touch
• lemniscal system : an oligosynaptic pathway in the ventral spinothalamic tract, projecting to the ventral posterolateral and ventral mediolateral nuclei of the thalamus
• extralemniscal system : a group of multisynaptic pathways in the spinothalamic tracts, projecting to the intralaminar nuclei of thalamus
• tractus spinothalamicus lateralis / lateral spinothalamic tract / paleospinothalamic tract : a group of nerve fibers in the lateral funiculus of the spinal cord that arise in the opposite gray matter and ascend to the thalamus, running with the lateral lemniscus in the brain stem; they carry sensory impulses activated by pain and temperature.
• spinocerebellar tract
• tractus spinocerebellaris posterior / posterior spinocerebellar tract / direct or dorsal spinocerebellar tract / tractus spinocerebellaris dorsalis : a group of nerve fibers in the lateral funiculus of the spinal cord, arising chiefly from the columna thoracica and ascending to the cerebellum by way of the posterior part of the lateral funiculus and then the inferior cerebellar peduncle; they carry sensory impulses activated by nerve endings in skin, muscles, tendons, and joints
• tractus spinocerebellaris anterior / anterior spinocerebellar tract / Gowers' column, fasciculus, or tract / ventral spinocerebellar tract / tractus spinocerebellaris ventralis : a group of nerve fibers in the lateral funiculus of the spinal cord, arising mostly in the opposite gray matter and ascending to the cerebellum by way of the anterior part of the lateral funiculus and then the superior cerebellar peduncles; they carry sensory impulses activated by nerve endings in skin, muscles, tendons, and joints
• descending tract : any bundle of nerve fibers that conveys impulses from the brain toward the periphery (-spinal)
• corticospinal (pyramidal) tract
• lateral corticospinal tract
• anterior corticospinal tract
• tectospinal tract
• rubrospinal tract
• tractus reticulospinalis / reticulospinal tract
• medial reticulospinal tract / pontoreticulospinal tract
• lateral reticulospinal tract /bulboreticulospinal tract
• tractus reticulospinalis anterior / tractus reticulospinalis ventralis / anterior reticulospinal tract / ventral reticulospinal tract / tegmentospinal tract : a group of fibers arising mostly from the reticular formation of the pons and medulla oblongata; chiefly homolateral, the fibers descend in the ventral and lateral funiculi to most levels of the spinal cord
• olivospinal tract
• vestibulospinal tracts
• medial vestibulospinal tract
• lateral vestibulospinal tract
• substantia grisea medullae spinalis / gray substance of spinal cord : it contains fewer myelinated fibers but more nerve cell bodies, unmyelinated nerve fibers, and blood vessels than the white substance.
• Rexed's laminae : an architectural scheme used to classify the structure of the spinal cord, based on the cytological features of the neurons in different regions of the gray substance. It consists of nine laminae (I–IX) that extend throughout the cord, roughly paralleling the dorsal and ventral columns of the gray substance, and a tenth region (lamina X) that surrounds the central canal and consists of the dorsal and ventral commissures and the central gelatinous substance.


• root cells : neurons whose axons form nerve roots
• columnae griseae medullae spinalis / gray columns of spinal cord : the three longitudinally oriented thickenings in the spinal cord, composed of the gray substance, and containing the nerve cell bodies. The columns are commonly referred to as cornua of spinal cord, because in transverse sections of the spinal cord they have the appearance of horns
• columna anterior or ventralis medullae spinalis / anterior or ventral column of spinal cord : the anterior portion of the gray substance of the spinal cord; it contains neurons that innervate the skeletal muscles of the neck, trunk, and limbs. In transverse section it is seen as a horn (cornu anterius or ventrale medullae spinalis / anterior or ventral horn of spinal cord) => anterior (ventral) root
• anterior horn cells
• a motoneuron / motor cell
• g motoneuron / motor cell
• striomotor column : an efferent column of the anterior horn of the spinal cord supplying striated muscle.
• nucleus spinalis nervi accessorii / spinal nucleus of accessory nerve : the group of cells in the anterior horn of C1-C5/C6 that form the spinal roots of the accessory (XI) nerve; continuous rostrally with the nucleus ambiguus
• anterolateral nucleus of spinal cord / nucleus anterolateralis medullae spinalis / ventrolateral nucleus of spinal cord / nucleus ventrolateralis medullae spinalis : a group of nerve cells in the gray substance of the anterolateral region of the anterior column of the spinal cord
• nucleus anteromedialis medullae spinalis / anteromedial nucleus of spinal cord / ventromedial nucleus of spinal cord / nucleus ventromedialis medullae spinalis : a group of nerve cells in the gray matter of the anteromedial region of the anterior column of the spinal cord
• retroposterolateral nucleus of spinal cord / nucleus retroposterolateralis medullae spinalis : a group of nerve cells in the gray substance of the retroposterolateral region of the anterior column of the spinal cord, which innervates the digital muscles.
• nucleus nervi accessorii / nucleus of accessory nerve / nucleus accessorius columnae anterioris medullae spinalis / accessory nucleus of anterior column of spinal cord : an irregularly shaped group of nerve cells formed by the axons of nerve cells entering the spinal part of the accessory nerve; found at the anterior border of the anterior column of the spinal cord in an intermediate or central position
• nucleus nervi phrenici / nucleus of phrenic nerve / phrenic nucleus / phrenic nucleus of anterior column of spinal cord / nucleus phrenicus columnae anterioris medullae spinalis : a centrally positioned group of nerve cells in the gray substance of the anterior column of the spinal cord, extending from C3 to C7, which innervate the diaphragm
• nucleus centralis medullae spinalis / nucleus centralis medullae spinalis / central nucleus of spinal cord : a group of nerve cells in the gray substance in the central region of the anterior column of the spinal cord.
• nucleus nervi pudendi / nucleus of pudendal nerve / Onuf's nerve : a group of somatomotor neurons in the ventral horns of the spinal cord at the S1 and S2 levels, innervating the musculature of the pelvic floor and the external urethral and external anal sphincters
• columna dorsalis or posterior medullae spinalis / dorsal or posterior column of spinal cord : the posterior portion of the gray substance of the spinal cord; it contains groups of motoneurons that extend the length of the cord and two groups that are limited to the thoracic and upper lumbar segments. In transverse section it is seen as a horn (cornu dorsalis or posterius medullae spinalis / dorsal or posterior horn of spinal cord) => posterior (dorsal) root
• nucleus spinalis nervi trigemini / spinal nucleus of trigeminal nerve / inferior nucleus of trigeminal nerve / nucleus inferior nervi trigeminalis / inferior or lower sensory nucleus of trigeminal nerve / nucleus of spinal tract of trigeminal nerve : a column of cells that lies along the medial aspect of the spinal tract, extending from the level of entry of the trigeminal nerve in the pons to the C2 segment of the spinal cord, where it is continuous with the dorsal gray column. The nucleus has several cytoarchitectonic subdivisions and the fibers of the spinal tract end in it
• substantia gelatinosa cornu posterioris medullae spinalis / gelatinous substance of posterior horn of spinal cord : gelatinous-appearing material in Rexed's laminae II and III of the posterior column of the spinal cord, consisting chiefly of Golgi type II neurons and some larger nerve cells.
• nucleus thoracicus posterior / posterior thoracic nucleus / columna thoracica / thoracic column / Clarke's column or nucleus / dorsal nucleus of Clarke / dorsal thoracic nucleus / nucleus thoracicus dorsalis/ Stilling's column or nucleus : a well-defined column of cells in the medial part of the posterior column of the spinal cord, immediately posterior to the intermediate column, usually extending from the eighth cervical segment caudally to the third or fourth lumbar segment; it gives rise to the ipsilateral posterior spinocerebellar tract
• Westphal's zone : a zone of the posterior gray column of the spinal cord in the lumbar region; it is said to contain the exodic fibers concerned in the patellar reflex.
• columna intermedia or lateralis medullae spinalis / intermediate or lateral column of spinal cord / intermediate zone of spinal cord : the lateral portion of the gray matter of the spinal cord, extending from the second thoracic to the first lumbar segment of the spinal cord; in transverse section it is seen as a horn (cornu intermedius or laterale medullae spinalis / intermediate or lateral horn of spinal cord)
• columna intermediolateralis medullae spinalis / intermediolateral column of spinal cord / autonomic column of spinal cord / columna autonomica medullae spinalis : the column of gray matter the cells of which (interomediolateral nucleus) form the intermediate column of the spinal cord
• formatio reticularis spinalis / spinal reticular formation / reticular formation of spinal cord / formatio reticularis medullae spinalis : numerous small islets of gray matter and intersecting white fibers which together constitute part of the intermediate gray substance of the spinal cord; in the thoracic cord, the formation occurs immediately dorsal to the lateral horn
• nucleus cervicalis lateralis / lateral cervical nucleus : a small group of cells in the lateral funiculus of the first and second cervical segments of the spinal cord, comprising a relay station in a spinocervicothalamic path.
• substantia visceralis secundaria medullae spinalis / second visceral substance of spinal cord : the gray substance lying ventral to the central intermediate substance.
• substantia intermedia lateralis medullae spinalis / lateral intermediate substance of spinal cord : the gray substance of the spinal cord that intervenes between the central intermediate substance, the intermediate column, and the anterior and posterior columns.
• commissura grisea anterior/posterior medullae spinalis / anterior/posterior gray commissure of spinal cord / gray commissure of spinal cord : the transverse band of gray substance surrounding the central canal of the spinal cord external to the central gelatinous substance; it connects the intermediate, anterior, and posterior columns
• substantia intermedia centralis medullae spinalis / central intermediate substance of spinal cord : the gray substance that makes up the gray commissure of the spinal cord.
• commissura grisea anterior medullae spinalis / anterior gray commissure of spinal cord / ventral gray commissure of spinal cord : the portion of the gray commissure anterior to the central canal
• commissura grisea posterior medullae spinalis / posterior gray commissure of spinal cord / dorsal gray commissure of spinal cord : the portion of the gray commissure posterior to the central canal
• heteromeral cells / heteromeric cells : nerve cells of the gray matter of the spinal cord whose axon processes pass to the white matter of the opposite side
• substantia gelatinosa centralis medullae spinalis / central gelatinous substance of spinal cord : the zone of gelatinous-appearing substance consisting chiefly of neuroglia but also containing a few nerve fibers and cells, that encircles the central canal of the spinal cord and is surrounded by the central intermediate gray substance.
• pars cervicalis medullae spinalis / cervical part of spinal cord : the part of the cord that is within the cervical part of the vertebral canal and gives rise to the eight pairs of cervical spinal nerves (segmenta cervicalia medullae spinalis [1–8]).
• Budge's ciliospinal center : a center in the lower cervical and upper thoracic portions of the spinal cord, connected with the dilatation of the pupil.
• intumescentia cervicalis / cervical enlargement : the enlargement of the cervical spinal cord at the level of attachment of the nerves to the upper limbs.
• pars thoracica medullae spinalis / thoracic part of spinal cord : the part of the cord that is within the upper three fourths of the thoracic part of the vertebral canal (in the adult) and gives rise to the twelve pairs of thoracic spinal nerves (segmenta thoracica medullae spinalis [1–12]).
• pars lumbalis medullae spinalis / pars lumbaris medullae spinalis / lumbar part of spinal cord : the part of the cord that is within the lower thoracic part of the vertebral canal (in adults) and gives rise to the five pairs of lumbar spinal nerves (segmenta lumbalia medullae spinalis [1–5]).
• ejaculation center : the reflex center in the lumbar spinal cord that regulates ejaculation of semen during sexual stimulation.
• Budge's or genital erection center : a reflex center in the sacral spinal cord that regulates erection of the penis or clitoris
• intumescentia lumbalis or lumbosacralis / lumbosacral enlargement : the enlargement of the lumbar spinal cord at the level of attachment of the nerves to the lower limbs
• anospinal centers : the centers for contracting the sphincter ani, for relaxing it (defecation center), and for the anal reflex; all are in the lumbar enlargement.
• micturition center : a center controlling the bladder and inhibiting the tension of the vesical sphincter, situated in the lumbar enlargement
• rectovesical center : a cord reflex center for the rectum and bladder
• conus medullaris / medullary cone / conus terminalis / terminal cone of spinal cord : the cone-shaped lower end of the spinal cord, at the level of the upper lumbar vertebrae
• cauda equina : the collection of sacral spinal roots that descend from the lower part of the spinal cord and occupy the vertebral canal below the cord; their appearance resembles the tail of a horse.
• filum spinale or terminale / meningeal, spinal or terminal filament or filum / filament of meninges : a slender threadlike filament of connective tissue that descends from the conus medullaris to the base of the coccyx; divided into a pial part (pars pialis fili terminalis) and a dural part (pars duralis fili terminalis), the dividing line being the lower border of S2 vertebra
Vascularization of spinal cord :
• spinal branches of ascending cervical artery
• spinal branch of iliolumbar artery
• spinal branches of posterior intercostal arteries
• spinal branches of highest intercostal artery
• spinal branch of lumbar arteries
• spinal branches of lateral sacral arteries
• spinal branch of subcostal artery
• spinal branches of vertebral artery / spinal arteries of Adamkiewicz
• spinal branch of dorsal branch of posterior intercostal arteries
• spinal branch of posterior intercostal vein
• coordination : the harmonious functioning of the motor apparatus of the brain which provides for the co-working of particular groups of muscles for the performance of definite adaptive useful responses.
• gait cycle : the series of movements of the leg and foot between one touch of the heel on the ground and the next time the same heel touches
• heel-toe gait : the normal, nonpathologic gait in which the heel touches down first and the toes last.
• stance phase : that part of the gait cycle in which the foot is in contact with the floor and the leg bears the body weight, comprising
• heel strike
• mid stance
• push-off
• swing phase : that part of the gait cycle in which the foot does not touch the floor and the opposite leg bears the body weight, comprising
• acceleration
• swing through
• deceleration
The rhythmic, alternating movements of locomotion have a sizeable local spinal control element in neurons bearing the EphA4 receptor, and can be generated even in the absence of stimulus from the brain.
• circadian rhythms regulate hundreds of functions in the human body, including :
• sleep and wakefulness
• body temperature
• blood pressure
• hormone production
• digestive secretion
• immune activity
Disruption of circadian rhythms has been linked to :
• insomnia
• jet lag
• stomach ailments
• coronary heart attacks
• depression
• cancer
8 core circadian genes have been identified so far : the levels of mRNA and proteins of these circadian genes, except those of Clock and CK1e, oscillate throughout the 24-hours period. The PAS domains are functionally important, as they provide surfaces that allow heterodimerization among different clock proteins.

		role in mammalian circadian clock	direct and indirect targets in growth regulation
bHLH-PAS TFs	Bmal1 / ARNT-like	physically associate with Clock; binds to E-box sequences to stimulate Per and Cry transcription; mutations alter behaviour rhythmicity in rodents	c-Myc (inhibition)
	Clock	physically associates with Bmal1 binds to E-box sequences to stimulate Per and Cry transcription; mutations alter behaviour rhythmicity in rodents	c-Myc? (inhibition)
	casein kinase Ie (CKIe)	phosphorylates Per to control Per stability and nuclear localization; mutations alter behaviour rhythmicity in rodents	b-catenin
	cryptochrome 1 (Cry1)	physically associate with and stabilize Per; mutations alter behaviour rhythmicity in rodents; might also be important in photoreception; suppress Bmal1/Clock transcription activity	c-Myc
	cryptochrome 2 (Cry2)		c-Myc
PER-ARNT-SIM (PAS)-domain proteins that function in the nucleus but apparently do not directly bind to DNA	Period 1 (Per1)	invoved in circadian phase resetting in SCN and in peripheral tissues; mutations in shorten circadian period in rodents
	Period 2 (Per2)	mutations alters behaviour rhythmicity, results in neoplastic growth phase and deficient DNA-damage response in rodents, and causes advanced sleep disorder in humans; stimulates Bmal1 expression	c-Myc, cyclin D1, p53, Mdm2, cyclin A1, Gadd45a
	Period 3 (Per3)	mutations do not affect behaviour rhythmicity in rodents

Deleting the 3 PAR bZip transcription factor family genes (D site of albumin promoter (albumin D-box) binding protein (DBP), hepatic leukemia factor (HLF) and thyrotrophic embryonic factor (TEF)) accelerates aging and causes severe epilepsy in mice. The triple knockout mice had a far shorter lifespan: 50% died within 2 months, and < 20% survived one year : more died on days when their cages were cleaned with a vacuum cleaner because of sound-induced epileptic attacks. The cause of the epileptic attacks might lie in Pdxk, whose expression is up-regulated by PAR bZip transcription factors^ref. Retinoic acid receptor-related orphan receptor-a (Rora) (mutated in "staggerer" mice with a shortened clock that is only 23.2 hours long) is a core circadian gene that reguilates transcxiptionof Bmal1, which in turn regulates transciption of cryptochrome, which subsequently inhibits the ability of Bmal-1 to activate cryptochrome's own transcription^ref.

The input pathways transmit information from environmental cues (mainly light signals - even insufficient for visual perception - received by a subset of melanopsin-expressing retinal ganglion cells, and transmitted directly to the SCN through the retinohypothalamic tract (RHT). In addition, the mammalian circadian genes Cry1 and Cry2 are also involved in photoreception by certain retinal neurons) to the central pacemaker. The retinal ganglion cells also project to the intergeniculate leaflet (IGL) and the olivary pretectal nucleus in the brain, which transmitr light signals indirectly to the SCN. The central pacemaker (in mammals reside in the 2 suprachiasmatic nuclei (SCN) of the anterior hypothalamus, each composed of 10,000 single-cell circadian oscillators) synchronizes with the environment to generate endogenous rhythms. The clock contains collections of cells that are sensitive to different inputs : when rats' normal 24-hour light-dark cycle is changed to one that lasts 22 hours, gene activity in some of the cells switches to the new 22-hour cycle, while other cells stuck to the old 24-hour routine^ref. Problems such as jet lag are caused when 2 of the clocks become out of step with each other. Although one of the brain clocks is sensitive to light signals from the retina, they have no idea what the other clock is sensitive to. The output pathways convert the instructions from the central pacemaker into daily oscillations in various physiological and behavioural processes. 4 different targets of SCN fibres have been identified in rodent brain : 3 of them are confined within the medial hypothalamus (the endocrine neurons that produce CRH, TRH, and GnRH; the autonomic paraventricular neurons (aPVN); and the intermeidate neurons, including the neurons in the subparaventricular nucleus of the hypothalamus (sPVN), the neurons of the dorsomedial nucleus of the hypothalamus (DMH), and the neurons of the medial preoptic nucleus (MPN)), while outside the hypothalamus the SCN neurons projectr to the paraventricular nucleus of the thalamus (PVT) and the IGL. The response of the SCN central clock to light stimuli is circadian time-dependent : light stimuli at the begininning of a subjective night results in the release of intracellular Ca²⁺ in SCN neurons, which, in turn, activates signalling pathways, such as the MAPK/ERK pathway, and the Ca²⁺/calmodulin and PKA pathways. Light exposure at the end of a subjective night activates NO and cGMP pathways, which leads to to phosphorylation of CREBP and subsequent activation of Per1 via a CRE in the promoter of the Per1 gene, whose activation is involved in the light-induced phase resetting in the SCN clock. Peripheral clocks are regulated by the SCN pacemaker, through both the autonomic nervous system (ANS) and neuroendocrine systems (hypothalamic-pituitary-gonadal (HPG) and the hypothalamic-pituitary-adrenal (HPA) axes : the latter case SCN neurons project from the hypothalamus to preganglionic parasympathetic and sympathetic neurons in brainstem nuclei, such as the dorsal motor nucleus of vagus (DMV) and in the intermediolateral cell columns (IML) of the spinal cord). The rhythmic expression of core circadian genes is observed in most peripheral tissues, and can be induced in cultured fibroblasts : however, the phase of circadian gene expression in peripheral tissues are delayed by a few hours, relative to those of SCN. Under certain conditions, however, such as when food supply is restricted at resting phase or in the case of DNA damage, the peripheral clocks can be completely uncoupled from the SCN central clock, and take their phasing cues from the feeding time or the damage, respectively, rather from the SCN. Peripheral clock timing can be affected by intracellular redox pathways, which relate to the intracellular metabolic rate, which is independent of the SCN pacemaker. The phase resetting in peripheral tissues by restricted feeding is a relatively slow process that can be quickly reversed when food is provided with a normal feeding schedule :  hormones such as glucocorticoids produced by adrenal gland inhibit the uncoupling of peripheral clocks from the central pacemaker with a negative feedback on the hypothalamus (the Per1 gene contains 2 almost-perfect GREs - one in its 5' promoter and another in its first intron), while IFNs and IL-1 produced by peripheral tissues and melatonin produced by pineal gland can modulate the activity of SCN. Clock-controlled genes are not required for clock function, despite the Bmal1-Clock heterodimer is regulated directly by the molecular clock. 2-10% of all mammalian genes are clock-controlled genes : most of these show tissue/organ-specific expression patterns and are involved in organ function. Only a small set ot clock-controlled genes are expressed in multiple organs : among them are genes that encode key regulators of cell-cycle progression. About 7% of all clock-controlled genes regulate either cell proliferation or apoptosis : these clock-controlled genes include c-Myc and Mdm2, TP53 and Gadd45a, as well as genes that encode the caspases, cyclins, transcription factors, and ubiquitin-associated factors that are involved in regulating the cell cycle and apoptosis. CKIe also functions in promoting cell proliferation by stabilizing b-catenin, resulting in cytoplasmic accumulation of b-catenin, mimicking the effects of WNT signalling. GSK3bis a functional homologue of the core circadian gene Shaggy in fruitfly. The molecular clock itself can be modulated by genotoxic stress in peripheral tissues, eg. g-radiation : the clock genes also respond to low levels of UV irradiation in cultured human keratinocytes. In fruitflies CKIIa directly phosphorylates Per, which regulates its ability to enter the nucleus : in mammals, CKII regulates cell-cycle progression by phosphorylating and activating c-Myc and phosphorylates p53 in response to UV irradiation. While 10% of genes expressed in the cerebral cortex do change in their level of expression between day and night, about half of them do so not because of circadian time but because of wakefulness and sleep, regardless of time of day.
• Sleep : as other circadian rhythms it depends on suprachiasmatic nuclei (SCN) of the anterior hypothalamus. Its period is 27-33 hours (ultradian rhythm). Normal duration ranges declines from 10 hours in infants to 6 hours in elderlies (stage 4 sleep also declines constantly, while REM sleep declines untile age 20, then experiences a plateau since age 20 until age 70, and finally declines)
• passive sleep theory (Bremer) : lack of trigeminal and vestibulocochlear afferences (e.g. section between colliculi in cat induces lethargy while section at C1 level doesn't impair sleep rhythm). Nowadays it has been replaced by
• active sleep theory (Moruzzi) : subtrigeminal section induces insomnia => sleep depends on equilibrium between deactivating ascending reticular formation (rostral NTS, ventral reticular nuclei and raphe nuclei) and activating rostral reticular formation (mesencephalic reticular formation and locus caeruleus) and preoptic area and the suprachiasmatic nucleus of hypothalamus inhibit the former.
• sleep cycle :
• g waves =>
• b waves =>
• 5 cycles composed as follows :
• slow (S)-wave activity (SWA) or sleep : d waves or q waves for 30-45' : acoustic dreams or nightmares. Parasympathetic prevalence, movement every 5-20', homeostasis (tendency to stability in the normal body states (internal environment) of the organism. It is achieved by a system of control mechanisms activated by negative feedback; e.g., a high level of carbon dioxide in extracellular fluid triggers increased pulmonary ventilation, which in turn causes a decrease in carbon dioxide concentration) and brain ischemia, but mental activity is absent only during stage 3 and 4
• stage 1 : > 50% are q waves
• stage 2 : K complexes and sleep spindles
• stage 3 : < 50% are d waves; K complexes and sleep spindles; increased GH incretion until the next stage 3
• stage 4 : > 50% are d waves
• stage 4 : as for first stage 4
• stage 3 : as for first stage 3
• stage 2 : as for first stage 2
• stage 1 : as for first stage 1
• rapid eye movement (REM) or D (for dream) or paradoxal sleep : orthosympathetic prevalence; difficult awakening, duration is longer and longer with following cycles; atonia except for eyes and middle ear, decreased GH incretion, poikilostasis (the maintenance of stability in the body state (internal environment) by behavioral activities involving movement and selection by the whole organism). Vivid dreams (acoustic dreams in blinded people). A patient used to experience 3 to 4 dreams per week. After an occipital lobe stroke, she had no dreams for a whole year, yet her REM sleep pattern and mental functions appeared otherwise unaffected. The patient reported no dreams even when woken in the midst of rapid eye movement (REM) sleep, which is normally associated with dreaming^ref. Psychologist Sigmund Freud believed that dreams offer a release for repressed feelings. Others think they help us empty our minds at the end of a busy day, or solve problems as we sleep. Others finally think that dreams are the cinema of the mind, helping to keep the brain entertained while we are asleep. The study also backs up reports of patients who lost both their dreams and their REM sleep for up to 1 year after taking certain antidepressant drugs : they are completely normal and have no memory problems.
• ischemia in parietal cortex, dorsolateral prefrontal cortex and posterior gyrus cinguli cause spatiotemporal disorientation and psychosis
• hyperemia in anterior gyrus cinguli, amygdala, parahippocampal gyrus, pontine reticular nuclei (which relay with lateral geniculate nuclei =PGO waves=>) and visual cortex (=> rapid eye movements) confers an emotional component to dreams
REM sleep can be further divided by EEG tracings into :
• phasic REM sleep
• tonic REM sleep
• a waves
• b waves
• g waves
In babies only quiet and activated sleep can be distinguished.
• rebounding after sleep deprivation : when you wake up much earlier in the morning than usual or when you work until midnight, you will naturally be sleepy the next day and will try to sleep much longer and deeper than usual. SWA somehow reflects a need to rest : someone who has been awake for a long time will display more pronounced SWA at the beginning of the night. Mice deficient in PGD₂ synthase (PGD2S), DP₁, or adenosine A_2A receptor can not rebound. PGD₂ is a sleep hormone that initiates the signal for sleep by binding its receptor, PGD2R. This signal is then transmitted to VLPO, a sleep center, via adenosine by way of adenosine A_2A receptor, believed to be a target of caffeine, which inhibits sleepiness.
It's learning, not usage, that elicits sleep : the hardest the work is to learn a new task, the higher is the boost in SWA activity on the posterior parietal cortex of the right hemisphere and the greater is the overnight improvement in morning performances. Brain circuits are reshuffling themselves to aid learning, rather than recovering from simple strain^ref. So why don’t more animals follow dolphins' example, remaining alert while part of their brain catches 40 winks? Why an animal should go to sleep all at once is still a mystery : it's extremely dangerous, yet most species keep doing it.
Whereas children sleep later and later as they get older, we undergo an abrupt shift at age 20, after which we start sleeping earlier again. The change is so sudden that researchers suggest it should be used to officially mark the end of adolescence. We all go through phases of puberty and adolescence before we reach adulthood. Both periods begin when the reproductive system starts maturing. Scientists agree that puberty ends when bone growth stops - at around 16 years in girls and 17.5 years in boys. But the end of adolescence - a concept that is part social, part psychological and part physiological - has always been less well defined. Our sleep and wake phases are regulated by an internal body clock. Each cycle runs at about 24 hours, but the exact timing varies from individual to individual. People with particularly early cycles, called "larks", tend to go to bed early and wake up early, whereas those with a late cycle ("owls") tend to be more active at night and sleep later in the morning. When the mid-points of each person's sleep (in other words, the time half way between when they go to sleep and when they wake up - on days when they had no work obligations) are plotted against each person's age, children tend to sleep later and later as they get older until the age of about 20. At that age, there is an abrupt shift in sleeping habits, and the sleep mid-point starts getting earlier and earlier again. It isn't proven that the shift is caused by behavioural or environmental factors (do teenagers sleep late because they go to the disco, or do they go to the disco because they sleep late?), but the abrupt timing of the shift suggests a biological cause. The timing of the shift also reflects the general trend of females to develop earlier than males. The women in the study that slept latest were 19.5 years of age, whereas the men's sleep got later and later until 20.9 years. An objective marker like this could be very helpful in a range of disease conditions : mental disorders such as schizophrenia and bipolar diseases are often accompanied by delayed sleep phases. It could be worth investigating whether changes in the timing of this shift could be used to spot the development of such disorders early on.
Despite mounting evidence that sleep duration is a risk factor across diverse health and functional domains, little is known about the distribution and determinants of sleep. In 2003–2004, the authors used wrist activity monitoring and sleep logs to measure time in bed, sleep latency (time required to fall asleep), sleep duration, and sleep efficiency (percentage of time in bed spent sleeping) over 3 days for 669 participants at 1 of the 4 sites of the Coronary Artery Risk Development in Young Adults (CARDIA) study (Chicago, Illinois). Participants were aged 38–50 years, 58% were women, and 44% were Black. For the entire sample, mean time in bed was 7.5 (standard deviation (SD), 1.2) hours, mean sleep latency was 21.9 (SD, 29.0) minutes, mean sleep duration was 6.1 (SD, 1.2) hours, and mean sleep efficiency was 80.9 (SD, 11.3)%. All 4 parameters varied by race-sex group. Average sleep duration was 6.7 hours for White women, 6.1 hours for White men, 5.9 hours for Black women, and 5.1 hours for Black men. Race-sex differences (p < 0.001) remained after adjustment for socioeconomic, employment, household, and lifestyle factors and for apnea risk. Income was independently associated with sleep latency and efficiency. Sleep duration and quality, which have consequences for health, are strongly associated with race, sex, and socioeconomic status.^ref

sleep	all	white women	white men	black women	black men
time in bed	7.51	7.84	7.34	7.55	7.10
sleep latency	22.33	13.30	18.52	28.36	35.93
sleep duration	6.13	6.71	6.09	5.90	5.10
sleep efficiency	80.8%	85.7%	82.4%	78.2%	73.2%

Web resources :
• Sleep Research Society
• Loughborough Sleep Research Centre
• Are you a lark, an owl, or a hummingbird ?
• Summary of acetylcholinergic circuits :
• spinal cord anterior horn cells / motor neurons
• basal prosencephalon => whole cortex
• striate interneurons
• pregangliar and postgangliar neurons of parasympathetic division and pregangliar neurons of orthosympathetic division of autonomic nervous systems (ANS)
• Summary of noradrenergic circuits :
• locus caeruleus => limbic system, hypothalamus, cerebral cortex
• spinal cord => locus caeruleus and spinal cord
• postgangliar neurons of orthosympathetic division of autonomic nervous sytem
• Summary of serotoninergic circuits :
• nucleus raphes pontis => diffuse projections
• spinal cord/pons => posterior horns of spinal cord (pain route)
• Summary of GABAergic circuits : main inhibitory neurotransmitter of encephalon
• diffuse cortical interneurons
• long projection ways
• Summary of glycinergic circuits : main inhibitory neurotransmitter of spinal cord
• Summary of glutamatergic circuits : main excitatory neurotransmitter of CNS
• cortical pyramidal neurons
• Summary of dopaminergic circuits
• nigrostriate tract
• nigrolimbic tract (from A10 to amygdala, nucleus accumbens, hippocampus, olfactory tubercle, ventral striatum, ...)
• nigrocortical tract
• tuberoinfundibular tract
• chemoreceptor trigger zone (CTZ)
• diadochokinesia / diadochokinesis / diadochocinesia : the function of arresting one motor impulse and substituting for it one that is diametrically opposite, to permit sequential alternating movements, as pronation and supination of the arm
• superior functions (see also Psychoneuroimmunology)
• general functions
• consciousness (see also disorders of consciousness) : 1. the state of being conscious, fully alert, aware, oriented, and responsive to the environment; having a clear or intact sensorium.  2. subjective awareness of the aspects of cognitive processing and the content of the mind.  3. the current totality of experience of which an individual or group is aware at any time
• conscious / consciousness : the part of the mind that is constantly within awareness, one of the systems of Freud's topographic model of the mind
• vigilance : alert watchfulness, particularly with regard to danger or other changes in the environment; attentiveness; readiness to respond to stimuli; ability to remain awake when one could be sleepined; vigilance can be full or fluctuating and is favorited by interest, anxiety, fear
• lucidity : the quality or state of having a clear mind; clearness of the mind; grade of knowledge of all internal and external experiences, presupponig an awake state; it is the focus of consciousness
• self-consciousness
• self activity
• unit consciousness
• identity consciousness
• self feeling
• subconscious : a term formerly used to include ...
• preconscious : the part of the mind that is not in immediate awareness but can be consciously recalled with effort, one of the systems of Freud's topographic model of the mind
• unconscious : the part of the mind that is not readily accessible to conscious awareness by ordinary means but whose existence may be manifested in symptom formation, in dreams, or under the influence of drugs; it is one of the systems of Freud's topographic model of the mind
• attention (see also disorders of attention) : 1. selective awareness of a part or aspect of the environment.  2. selective responsiveness to one class of stimuli
• voluntary or conative attention : the observer search for an object
• involuntary attention : the object attracts the observer
• specific functions
• memory (see also disorders of memory): that mental faculty by which sensations, impressions, and ideas are recalled.
• symbolia : ability to recognize the nature of objects by their distinctive forms
• gnosia : the faculty of perceiving and recognizing
• praxis : the doing or performance of action
• phasia : the doing or performance of speech
General pathways (the memory system theory) :
• environmental inputs =>
• immediate, ultrashort-term or sensory-perceptual memory / sensory recordings : tracings kept for analysis and recognition (engram : in psychology, the lasting trace left in the psyche by any experience; a latent memory picture)
• sensory storage system : the shortest type of memory, maintaining for less than a second briefly perceived stimuli
• echoic memory : that part of the sensory storage system that holds auditory stimuli.
• iconic memory : that part of the sensory storage system that holds visual stimuli.
• eye or visual memory : memory for visual impressions
• tactile memory
• kinesthetic or motor memory : the memory of movements in the limbs and other parts of the body.
There are at least 3 separate areas for processing and recognising faces. The inferior occipital gyri process the physical features of the face (such as eyes and hair), the right fusiform gyrus appears to distinguish between faces, perhaps by comparing the face to known ones, and the anterior temporal cortex retrieves information about that person, such as their name. Although the physical features gradually change from one face into another, subjects looking at the images tend to "suddenly flip" from seeing the countenance of film star Marilyn Monroe gradually morphed into that of former British prime minister Margaret Thatcher, or that of James Bond actor Pierce Brosnan transformed into current prime minister Tony Blair^{ref1, ref2}.
• short-term memory (STM) has a capacity limited to about 7±2 items. It can retain recordings in an ordinate sequence. It is lost within a brief period beofre or after the reply has occurred (from a few seconds to a maximum of about 30') unless reinforced to ...
• primary memory refers to how many things a person can keep in mind at one time, an example being the longest string of numbers a person an repeat without making an error
• visual short-term memory (VSTM) : contrary to our rich phenomenological visual experience, our VSTM system can maintain representations of only 3-4 objects at any given moment. For over a century, the capacity of visual memory has been shown to vary substantially across individuals, ranging from 1.5 to about 5 objects. Indeed, the precise limit is determined by each individual's memory capacity, such that the activity from low-capacity individuals reaches this plateau much sooner than that from high-capacity individuals^ref. Very short-term memory capacity is thought to be related to intelligence and depends on the posterior parietal cortex^ref.
• the average VSTM capacity when using American Sign Language (ASL) rather than English is only 5±1 items. Contrary to previous interpretations, this difference cannot be attributed to phonological factors, item duration or reduced memory abilities in deaf people. Despite this difference in STM span, hearing speakers and deaf ASL users have comparable working memory resources during language use, indicating similar abilities to maintain and manipulate linguistic information. The shorter STM span in ASL users therefore confirms the view that the spoken span of 7±2 is an exception, probably owing to the reliance of speakers on auditory-based rather than visually based representations in linguistic STM, and calls for adjustments in the norms used with deaf individuals^ref
• working memory refers to keeping information in mind while engaging another task. An example would be remembering the last word in a series of sentences while engaged in remembering the meaning of each sentence
• long-term ("reference") memory (LTM) : memory that is retained over long periods of time
• declarative memory (can be expressed verbally)
• semantic memory : the memory for members of a given category. It involves the retrieval of conceptual information. Examples are the ability to define words or to name the authors of particular boks.
• episodic memory : the memory for episodes in a sequential order. It involves recollections that are actively retrieved within the context of a prior personal experience, such as where the keys of the automobile were left, what an individual has been requested to purchase at a pharmacy, or when a particular medication should be taken.
• autobiographic memory
• heterobiographic memory
• prospeptic memory : the memory for appointments (mental agenda)
• nondeclarative memory (learnt behaviors)
• procedural memory : the memory for finalistic actions. It refers to a recollection that does not require conscious awareness. This is the last memory component to be affected in amnesias
Protein synthesis, localized to the dendrites, enables a function known as long-term facilitation, which is a strengthening of synaptic connections in the large neurons of the sea slug Aplysia californica. cytoplasmic polyadenylation element-binding protein (CPEB), which marks active synapses, behaves like a prion in yeast cultures, and its alternative self-perpetuating form—generally associated with disease states for other prions—appears to be the protein's active form. It maintains that strengthening process by spurring local translation of ubiquitous but dormant mRNA, such as those for structural and regulatory molecules, which allow a synapse to grow : it is a relatively low-energy way of doing long-term memory. First described in maturing Xenopus oocytes, CPEB is highly conserved in vertebrates and invertebrates, but was thought to be largely just associated with germ-cell development. CPEB was found in post-synaptic regions of mammalian neonatal brains
• physiological memory : the physical storage of engrams in the brain by means of RNA.
• anterograde or remote memory / palinmnesis : a memory serviceable for events long past, but not able to acquire new recollections
• replacement memory : the replacing of one memory with a different one
• screen memory : a consciously tolerable memory serving to “screen” or conceal another memory that might be disturbing or emotionally painful if recalled.
• learning
• our brains are following the laws of artificial intelligence driving robotic behaviours : while learning good from bad, both the insula cortex and the ventral striatum are activated^ref
• human girls tend to catch on faster than boys when learning skills such as writing and drawing. These manual tasks are not dissimilar to the chimpanzee technique of using a stick to fish for termites : females pick up this skill at around 30 months of age, whereas males are usually twice as old as that. Male chimpanzees are more easily distracted, choosing to spend their time swinging in trees, turning somersaults and wrestling with each other. This failure to pay attention is reflected in their poor termite hauls, but the males are not necessarily wasting their time. While termites are a valuable food for females, males often catch larger animals such as monkeys. Their rough-and-tumble play may be a way to hone their hunting skills. Females, who often have youngsters in tow, tend to stick to termites as a safer alternative to the thrill of the hunt : hunting is a very vigorous, dangerous activity in the treetops; it is difficult for females to do. The young males' antics may also shape future social interactions : playful wrestling bouts may be a way to form alliances or establish hierarchies^ref.
• writing : the inscription of letters or other symbols, and of words, phrases, and sentences, so that they may be perceived by the eyes or, by the blind, through the fingertips.
• mirror writing : writing in which the right and left relationships of letters and words are reversed, as if seen in a mirror.
• Humans can learn skills without remembering what they have done. Such learning is seen in monkeys, but experts were unsure whether humans retained this ability, because of our tendency to think consciously about whatever we are learning. Most people gather information and abilities through a process of 'declarative' learning, in which they remember the act of learning as well as the new skill or knowledge itself. Hopefully, you'll recall reading this article, as well as remembering the nuggets of information it contains. This process of explicit thought offers a fast route to learning, but requires sophisticated mental machinery. Declarative learning is centred on a brain region called the medial temporal lobe, which is thought to coordinate the storage of memories in the brain. Other animals, which lack our cognitive powers, use a slower, more primitive method called habit learning. If one item in a pair of objects is designated the 'correct' item, monkeys can learn to select this particular item by simple trial and error. Without realizing they are doing it, they gradually acquire the habit of picking the right option. Neuroscientists had been unsure whether humans share this primitive ability, or whether our capacity for conscious learning has rendered it obsolete. To find out, the task of identifying the correct items in 8 pairs were given to patients with severe damage to their medial temporal lobe. Healthy humans can master the task in no time, because of declarative learning. The study's two volunteers, both of whom had permanent amnesia as a result of encephalitis, did not remember the objects or the task at the start of each session. But they were still able to master the task, albeit over several weeks. Despite ultimately achieving success rates of 85% and 92.5%, the two patients could not explain why they thought a given item was the correct one to choose. The patients were surprised and one asked 'How am I doing this?'. To prove that the subjects had learned the task purely by rote, the researchers gave them all of the objects together and asked them to sort them into 'correct' and 'incorrect' groupings. They were unable to do this, despite having mastered the task when presented with the items in pairs^ref. The fact that humans can learn in the absence of conscious memory is a surprise. We thought it unlikely that such successful habit learning would be revealed, because we expected that performance would be dominated by efforts to engage in declarative memory. The exact function of habit learning in humans remains unclear. but it has a fundamental role in shaping healthy minds as well as those of amnesiacs. Here arise our preferences, dispositions, skills and myriad ways of interacting with the world
Memories of images begin to fade days or even hours after viewing, whereas recall of smells remains unimpaired for as much as a year^{ref1, ref2}.
Is a single cell in your brain devoted to Jennifer Aniston or Bill Clinton? Maybe so. A recent experiment showed that single neurons in people's brains react to the faces of specific people. Researchers see the findings as evidence that our brains use fewer cells to decode a given image than previously thought. The subject of visual processing has sparked much scientific speculation in the past. Exactly how our brains extract meaning from an image remains unclear. At one end of the spectrum of possibilities, a network of cells would process various bits of information in a scene and piece it all together to form an understandable picture. At the other extreme, the brain would contain a separate neuron to recognize each and every object in the world. Neurobiologist Jerome Lettvin coined the term 'grandmother cell' to parody this view, as it would mean that the brain contains a specific cell to recognize one's own grandmother. Very few experts believe that grandmother cells exist. 8 patients suffering from epilepsy had been temporarily implanted with devices to monitor brain-cell activity as part of their treatment : this opportunity was used to monitor the firing behaviour of their neurons. Using a laptop, they presented the subjects with a series of one-second snapshots of celebrities, animals, objects and landmark buildings. Each person was shown a total of almost 2,000 pictures; in each sitting they saw about 90 pictures showing roughly a dozen distinct items. The recordings taken as they viewed the photographs revealed just how selective cells within the medial temporal lobe - located deep inside the brain- can be. For example, a neuron of one patient responded almost solely to different pictures of Bill Clinton. These types of cell are involved in sophisticated aspects of visual processing to identify a person, for example, rather than just a simple shape. Various pictures of Jennifer Aniston elicited a response in a single neuron inside the medial temporal lobe of another patient. Interestingly, images of her with her former husband Brad Pitt did not sway this cell. A lone neuron in one subject responded selectively to various pictures of the actress Halle Berry - as well as drawings of her and her name written down. Other cells were found to respond to images of characters in The Simpsons or members of The Beatles. These brain cells probably respond to a range of different items, but that this limited study didn't include all the various pictures that might make a particular cell light up. Despite appearing to find a 'Halle Berry cell', nobody's saying that it's a grandmother cell. Nevertheless, the results hint that we might use fewer brain cells to recognize familiar objects than previously thought^ref.
• intelligence (see also disorders of intelligence): the ability to comprehend or understand, according to the background of knowledges, the effectiveness of psychic functions and the interest in problem solving. It is assessed with intelligence test : a set of problems or tasks posed to assess an individual's innate ability to judge, comprehend, and reason
• Army General Classification test : an intelligence test whose results are used for placement in the military.
• alpha test : a test of intelligence administered by the U.S. Army in World War I to persons who could read.
• beta test : a test of intelligence administered by the U.S. Army in World War I to persons who could not read or did not speak English
• group test : a test of intelligence or aptitude given to a number of persons at one time.
• aptitude tests : tests given to determine aptitude or ability to undertake study or training in a particular field
• performance test : an intelligence test in which the subject is required to carry out certain actions evaluating abilities, capacities and acquired knowledges rather than to answer questions.
• Porteus maze test : a performance test in which the subject is required to trace with a pencil through printed mazes of increasing difficulty
• Goodenough draw-a-man or draw-a-person test : a method of testing the general intelligence of children by asking the subject to draw a picture of a man to the best of his or her ability.
• Goodenough-Harris drawing test : a revision of the Goodenough draw-a-man test, in which scoring emphasizes the presence or absence of body and clothing detail rather than artistic skill
• Binet's test : a method of testing the mental capacity of children and youth by asking a series of questions adapted to, and standardized on, the capacity of normal children at various ages. According to the answers given, the mental age of the subject is ascertained.
• Kuhlmann's test : a modification of Binet's test for use in infants
• Stanford-Binet test : a modification of Binet's test, translated, adapted, and standardized on children in the USA
• Cattell Infant Intelligence Scale : a test of general motor and cognitive development, assessed by performance of tasks, in the first 18 months of life.
• Wechsler Intelligence Scale for Children (WISC) : a group of tests for assessment of intellectual functioning in children ages 5 to 15
• WISC revised (WISC-R)
• Wechsler-Bellevue test => Wechsler Adult Intelligence Scale (WAIS) : a group of tests for assessment of intellectual functioning in adults.
• WAIS revised (WAIS-R)
• intelligence quotient (IQ) = (patient's mental age as ascertained by the Binet test / chronological age) x 100. Normal if between 90 and 110. A few have IQ > 110 (hyperdotated)





Theories :

• anarchic theory : sum of particular functions
• monarchic theory : highly differentiated activity
• factorial theory : a general (G) factor coordinates the whole of specific (S) factors
Ever since German anatomist and physiologist Frederick Tiedmann wrote in 1836 that there exists “an indisputable connection between the size of the brain and the mental energy displayed by the individual man,” scientists have been searching for biological evidence to prove his claim. > 25 years ago, a weak correlation was found between IQ and overall brain size. Others have suggested that level of intelligence is due to the size of the frontal lobe. Now, however, a common view is that more subtle characteristics are likely to be involved, such as the speed at which nerve impulses travel in the brain, or the number of neuronal connections present. A new study challenges that idea, suggesting that people with high IQ scores had significantly more grey matter in 24 brain regions known to be related to memory, attention and language. Only about 6% of the total grey matter in the brain seems to be related to IQ. For all age and sex groups, it is now very clear that brain volume and intelligence are related, based on the most comprehensive study of this kind, drawing conclusions from 26 previous – mostly recent – international studies involving brain volume and intelligence. It was only 5 years ago, with the increased use of MRI-based brain assessments, that more data relating to brain volume and intelligence became available. On average, intelligence increases with increasing brain volume. Intelligence was measured with standardised intelligence tests, which have important consequences on peoples' lives, such as where they’ll go to college or what kind of job they get. Critics have called the tests inaccurate or irrelevant to the real world, but when intelligence is correlated with a biological reality such as brain volume, it becomes harder to argue that human intelligence can’t be measured or that the scores do not reflect something meaningful. Employers will appreciate his findings because intelligence tests are the single best predictor of job performance. On average, smarter people learn quicker, make fewer errors, and are more productive. The use of intelligence tests in screening job applicants has substantial economic benefits for organizations. Before MRIs, scientists often used external skull measurements or waited until a person died to estimate brain size. The external skull measurements were only approximate estimates of brain volume^ref.
Dominant rats have around 30% more neurons in their hippocampus than their subordinates : around 9,000 new nerve cells are born every day, but most die within a week. In the dominant animals, however, the new cells survive for longer^ref. The finding hints that social hierarchies can influence brain structure, and raises questions over the use of standard animal behaviour tests in laboratory research : studying rats in burrows is likely to be much more relevant to understanding human behaviour than tests carried out in standard cages as standard laboratory housing may suppress individual variability, so the behaviour you see may be different from that you would observe in nature. Most laboratory protocols suppress individual differences between test animals. But many researchers are now moving towards tests that enhance individual behaviour. These models should be more relevant to human disease
A person's 'need to evaluate' (NE) describes how much he or she forms opinions about things encountered in everyday life : it seems to foretell some aspects of our political behaviour. People with a high NE were much more likely to ally themselves to either the Republican or Democratic party in the USA, be a political activist or glean political information from the media. They were also simply more likely to vote. This was true even once their age, sex, income and education level had been taken into account^ref. One body of work, for example, suggests that those brought up to follow strict rules tend to favour harsh punishments for others, as do those with low self-esteem. In future, pollsters might judge whether people are likely to vote by asking a couple of questions to estimate their NE
Highly intelligent people use slightly different brain circuitry to solve IQ test problems than their less gifted peers. The findings are sparking some debate, because different experiments have given different results, leading to varying opinions on how highly intelligent brains work. Nonetheless, researchers say they’re hopeful that the findings have enough in common to eventually give clear answers—and possibly, some speculate, help researchers devise techniques to improve thinking abilities. One new study has found that although people show increased activity in several brain regions while taking IQ tests, gifted people show even greater activity in these regions. This difference was especially pronounced in a zone called the posterior parietal cortex, considered important for “working memory”—the ability to hold items actively in mind, as when remembering a phone number for a few seconds. Thus, high intelligence might partly be a fairly straightforward matter of more working memory capacity. But the claim of a special role for this brain area was somewhat unusual in light of previous studies. Of several past studies of highly intelligent people’s brain functions, most hadn’t suggested a special role for this region, though most did include it among several areas thought to be important for intelligence. However, at least one previous study did find a special role for this region. Also, this area was enlarged in Einstein’s brain. Nonetheless, the evidence overall doesn’t point to one brain area as having overarching importance in intelligence. The idea that there is only one site for general intelligence has been proposed from time to time, but the bulk of the evidence refutes it. The evidence does, however, point to a specific network of brain areas underlying intelligence. Thus, this whole network could be studied to get a better understanding of intelligence. Most of this network lies in the cerebral cortex : the network has been identified in over 20 imaging studies of both brain structure and function. In structural studies, we have found very specific brain areas where more gray matter goes with higher IQ. Gray matter refers to parts of the brain consisting mostly of the central bodies of brain cells, rather than their long, thread-like extensions, which they use to transmit signals to other cells. IQ stands for intelligence quotient, a measure of reasoning ability as determined by an intelligence test. The cerebral cortex areas Haier identifies as key for intelligence include parts of the parietal cortex but also parts of areas known as the frontal, temporal and occipital cortex. These have been tied to attention and goal-seeking behavior, language abilities, and visual information processing, respectively. One variable that has confounded IQ-test studies is that some of them actually find lower, not higher, brain activation among gifted people. This fits neatly with a hypothesis proposed by Haier—that more intelligent brains work more efficiently, so that brain circuits unnecessary for the task at hand aren’t used. But the phenomenon has perplexed researchers on the whole, since some studies show the opposite. Haier has proposed that the phenomenon may be related to how hard a task is for a particular person. Haier and colleagues in 1995 arranged a study so that gifted and average people were assigned problems that were equally difficult for their intelligence level, and found that the effect vanished. Overall, the effect seems to reflect the fact that intelligent people have more activity in less brain volume. But the effect is still not fully understood; for instance, it seems more pronounced in males than in females, for reasons unknown. Lee proposes that a better understanding of the biological basis of intelligence could help researchers devise techniques to improve learning abilities. There’s no evidence that one can enhance intelligence as a whole, but one might be able to stimulate activity in certain brain areas to enhance learning (Kun Ho Lee, Neuroimage)
• thinking : ideational mental activity (in contrast to emotional activity); the flow of ideas, symbols, and associations that brings forth concepts and reasons.
• abstract thinking : that characterized by the ability to appreciate and use metaphors, concepts, and generalizations, to think symbolically, to reason and predict, and to formulate hypotheses and draw conclusions
• concrete thinking : that grounded in the literal, limited in the use or understanding of metaphor or nuance, and representing objects or ideas as specific items rather than as abstractions, generalizations, or totalities
• preoperational thinking : a type of thinking usually characteristic of children between the ages of approximately 2 and 7; it is characterized by a capability for symbolic representation but also by egocentricity and by lack of true understanding of relational terms, the principles of conservation, or the ability to arrange series of objects in order.
• formal operations : a form of thinking following the stage of concrete operations and representing the final, most mature state of thinking; usually occurring after the age of 11 and characterized by the emergence of true logical thought, with the capability for deductive reasoning, abstract thinking, formulation and testing of hypotheses, appreciation for multiple perspectives on an issue, and the manipulation of ideas and concepts.
• primary process thinking : in psychoanalytic theory, the primitive thought processes deriving from the id and marked by illogical form, preverbal content, an emphasis on immediate wish fulfillment, and an equating of thought and action; characteristic of childhood and of dreams.
• secondary process thinking : in psychoanalytic theory, the more sophisticated thought processes, based on logic, obeying the rules of causality, and consistent with external reality; characteristic of mature conscious thought.
• thinking too hard about simple actions interferes with the learning process. Scientists already knew that consciously trying too hard to learn can cause trouble. The earliest demonstration of this came from a study in 1976, in which college students were asked to memorize strings of letters : those who were told from the start that there was a regular pattern within the letters found it harder to discriminate between strings that did or did not contain the pattern. The brain activity (as monitored by fMRI) of people who are learning without consciously trying (implicit learning) lacks a notable boost in the activity of the right frontal lobe found in people who are putting deliberate effort into mastering the challenge. The frontal lobes are valuable in a crisis, when it is necessary to make a quick decision about which course of action to take. But this conscious processing might actually inhibit the automatic learning of simpler tasks. So should we give our brains a break and stop trying to learn? It depends on the type of task, says Fletcher. For example, people who are learning to ski should try to relax as they go down the slope. If you work out every turn in advance it disrupts the processes at the motor level, but when it comes to mastering textbooks, some concentration will still be required.
• perception : the conscious mental registration of a sensory stimulus.
• depth perception : the proper recognition of depth or the relative distances to different objects in space.
• extrasensory perception (ESP) : knowledge of, or response to, an external thought or objective event by means other than the senses.
• feelings :
• somatic
• pleasure
• perfumed scent
• winning money
• caress
• food pleasure : when subjects consume slurries of tasteless cellulose mixed to the thickness of water, corn oil or runny syrup, and a mouthful of bland vegetable oil, thicker solutions trigger a brain area that partly overlaps with one known to be activated by taste : the brain builds a picture of what is in the mouth based on both taste and texture. Fatty mixtures also fire up the cingulate cortex : this backs up food-lovers' wisdom that a dollop of butter or cream makes dinner all the more appealing. Probably humans evolved ways to detect the textures of energy-dense foods, such as fats, so that they could gobble them down in case food becomes scarce.
• well-being
• satiety
• fatigue
• malaise
• psychical
• joy
• shiness
• force
• shameness
• ethico-spiritual
• researchers have long known that people place different amounts of faith in their different senses. This is exploited by ventriloquists, who fool us into thinking sound is coming from someplace it isn't by relying on the fact that people use their vision more heavily than their hearing to locate the source of a sound. This is because the eye's retina is very sensitive to the direction of light that hits it, while the ear isn't so sensitive to the direction of a noise. The cinema is the classic ventriloquist effect : we assume the voices are coming from the actors on the screen instead of from the loudspeaker somewhere else in the room. It is commonly thought that vision will always dominate over hearing in such situations, but instead the ventriloquist effect results from near-optimal bimodal integration. Instead, both visual and auditory cues are weighted by the brain, with one cue compensating for the other when it is less reliable. When 2 small and defined circles are flashed onto a computer screen, one after the other, and asked viewers which circle was further to the left, participants rely on their sight rather than their hearing to gauge the direction of movement. But, intriguingly, when the circles are large and fuzzy, observers are more likely to believe their ears over their eyes, and use the sound to judge the direction of movement (reverse ventriloquism), and it occurs because large, blurred blobs are perceived as being less trustworthy than small, sharply defined ones. When both stimuli are perfectly evenly weighted, the 2 senses would work together to produce a better judgement of motion than when only one sense was called upon.
• your eye movements may reveal something about your cultural background, researchers have found, in a study comparing the way Easterners and Westerners look at photos.

Sample map of a Chinese viewer's gaze on a photograph :

Sample map of an American viewer's gaze on a photograph :

Chinese and American people tend to move their eyes over the photos in distinctly different patterns. Previous studies have revealed differences in thought processes between cultures: North Americans tend to be analytical and pay more attention to foreground objects, while East Asians tend to be more holistic and rely on contextual information. Cultural differences emerged within the first second of viewing : American students looked at the foreground object more quickly and fixated on it longer than did Chinese students, while Chinese students made more quick glances to the background. Previously reported cultural differences in thought processes may be related to variations in what people focus on as they view a scene. These variations may reflect greater importance of context and social interrelationships in East Asian culture compared with Western culture^ref.
• perception of physical attractiveness :
• waist-to-hip ratio (WHR), which relates to the distribution of fat between the upper and lower body, and gives an overall indication of health.
• body mass index (BMI) = weight [kg] / h² [m]. Although more commonly used to describe health rather than attractiveness, previous investigations have shown that women with a BMI of 18 to 19, for example, are ranked as the most lovely. That's at the slim end of the normal BMI range, 18.5 to 24.9.
• volume-height index (VHI) = V [m³] / h² [m], proposed by Jintu Fan, a clothing scientist at the Hong Kong Polytechnic University, believed in the importance of the BMI, but doubted that it fully captures a person's physical appeal. Viewers cannot estimate another person's weight by just viewing them, so he felt this may be a consequence, rather than a direct cue to body attractiveness. He and his fellow researchers turned their attention to size, reasoning that it is easier for us to judge another person's volume than his or her weight.
• female VHI : if VHI were used alone to rate attractiveness, a woman with a straight tube of a body could come out as well as a curvaceous one : people size up other body proportions when they rate attractiveness. They gauge how long a woman's legs are relative to her total tallness, or assess waist-to-hip ratios. But this doesn't mean that those with a roving eye are churning through tortuous sums in their heads to assess attractiveness. People probably make an instinctive assessment of shape that tallies with more accurate measures of size. Both sexes were in agreement about the most attractive body shape : the most attractive VHI for females is around 14 l / m^2ref.
• male VHI : the group used lasers to produce 3D scans of 94 men (69 of them Chinese and the other 25 Caucasian) and then calculated their VHIs from the measurements. In the next step, Fan and his colleagues asked 43 male and female volunteers to rate how attractive they found each of the 3D body images on a scale of 1 to 9, and then compared these ratings with various parameters including WHR, BMI and VHI. They found that VHI was the best at predicting how attractively a body would be rated. The average VHI of the males in the sample group was just over 20 l / m². But the researchers found that female viewers preferred slimmer body types, with an optimum VHI of around 17.5 l / m², whereas males appreciated a slightly beefier 18 l / m² the most. All the viewers were from Hong Kong and were of Chinese origin, however, so the most attractive body type might be different for other societies or ethnic groups^ref.
A person's volume may be a better indicator of their fitness level than their body weight : for example, a heavy person with a solid muscular body is fit, although he may have a relatively high BMI.
• female physical attractiveness
• how female facial attractiveness varies during their menstrual cycle, to see if that might convey the level of their fertility (other animals have more obvious ways of letting their mates know when they are fertile: for example, female chimps' genital areas swell and turn pink) : 51-59% of both men and women choose the most attractive woman's face picture as that showing a fertile woman - a statistically significant result. A few women had changed their hairstyle between pictures : covering up the hair and ears on the pictures did not make much of a difference to a woman's looks as far as the men were concerned. But, while women still picked the picture of the fertile woman more often, they did so less reliably when the hair was disguised. The results indicate that men and women rely on different cues to judge another woman's attractiveness. Women in particular may have evolved to be sensitive to other women's cycles : this would let them assess their biggest competitor when vying for mates^ref
• earlier studies have indicated that men might use other clues, such as female body odour, to help them pinpoint their partner's fertility. Others have shown that a woman's ears and breasts actually become more symmetrical in the days leading up to ovulation.
• female intrasexual competition decreases female facial attractiveness : when women are at the most fertile point in their monthly cycle they tend to have a lower opinion of other women's looks. And that's not just because of mood swings : menstrual phase had no effect on how the same women rated the looks of men^ref. This could even help to explain the popularity of magazines featuring photos of celebrities looking less than their best
• women prefer masculine-looking men when they are ovulating. At other times they prefer softer features that are associated with more social and caring behaviour
• sympathy : compassion for another person's thoughts, feelings, and experiences
• empathy : intellectual and emotional awareness and understanding of another person's thoughts, feelings, and behavior, even those that are distressing and disturbing. Empathy emphasizes understanding, sympathy emphasizes sharing, of another person's feelings and experiences
• empathy for pain lights up the same affective components of the brain as personal injury despite it does not involve sensory components of pain : empathic response probably enables us to forge loving bonds, such as between a mother and child and it has an evolutionary function. In a broader sense, empathy can help us understand what someone else is feeling , be it pain, joy or anger : such an ability may serve to help ward off danger.
• insight : in psychiatry, the patient's awareness and understanding of the origins and meaning of his attitudes, feelings, and behavior and of his disturbing symptoms; self-understanding
• intellectual insight : understanding of the objective reality of a situation without the ability to apply that knowledge in the future or without true feeling.
• true insight : understanding of the objective reality of a situation coupled to true feeling and to the motivation and capability to use the understanding in the future
• humans have a unique ability to learn more than one language — a skill that is thought to be mediated by functional (rather than structural) plastic changes in the brain. Learning a second language increases the density of grey matter in the left inferior parietal cortex and that the degree of structural reorganization in this region is modulated by the proficiency attained and the age at acquisition. This relation between grey-matter density and performance may represent a general principle of brain organization^ref
• non-natives find each other at least as intelligible as native English speakers, regardless of whether they share a first language, as long as the proficiency of the speakers is not too low. Natives find each other more intelligible than non-natives, just as one would suspect.
• because human languages vary in sound and meaning, children must learn which distinctions their language uses. For speech perception, this learning is selective: initially infants are sensitive to most acoustic distinctions used in any language, and this sensitivity reflects basic properties of the auditory system rather than mechanisms specific to language; however, infants' sensitivity to non-native sound distinctions declines over the course of the first year. The sensitivity of 5-month-old infants in an English-speaking environment to a conceptual distinction that is marked in Korean but not English; that is, the distinction between 'tight' and 'loose' fit of one object to another. Like adult Korean speakers but unlike adult English speakers, these infants detected this distinction and divided a continuum of motion-into-contact actions into tight- and loose-fit categories. Infants' sensitivity to this distinction is linked to representations of object mechanics that are shared by non-human animals. Language learning therefore seems to develop by linking linguistic forms to universal, pre-existing representations of sound and meaning^ref
• existing languages do share fundamental rules. But this may simply be because different languages have influenced each other as they evolved. It has long been debated to what extent our brains are a 'blank slate', able to learn any structure of language to which we are exposed, or whether they are hard-wired with grammatical rules. Linguists have attempted to answer the question by examining languages as they arise. For example, when people who speak different languages are pulled together, as they were by immigration or slavery, they rapidly evolve a pidgin language that can be polished over the years into a more sophisticated creole. But in these cases the communications are based on pre-existing languages. Deaf Nicaraguan kids in the country lived in effective isolation until they were brought together in specialist schools in the late 1970s and 80s. Once the deaf children started to mingle, they began to communicate in their free time using gestures. They tend to stick with the signs they have acquired by the time they reach adolescence, so oldest set of children uses a relatively crude set of gestures. But younger generations have continued to refine them, forming a completely new language with its own grammatical rules. A property common to most spoken and sign languages around the world is that expressions are constructed from pieces with smaller meaning. By the second 'generation' of children, those speaking the newborn Nicaraguan language had a similar system. Rather than have one sign for 'rollingdown', which would be the most economical option, they had 2 separate gestures for "rolling" and "down". This suggests that children are born with a natural ability to break down language in this way. Hard wired rules like this help explain how language is acquired so easily. It is not clear whether this ability to break concepts into parts is specific to language, or whether it might be part of a wider ability that could be applied to other learning tasks. It takes years and years of evolution, and then one language emerges in a generation.
• the Pirahã tribe, a hunter-gatherer group of about 200 people, whose counting system consists of words which mean, approximately, 'one', 'two' and 'many'. Psychologists, anthropologists and linguists have long wondered whether animals, young children or certain cultures can conceptualize numbers without the language to describe them. The tribe members struggle to perform these tasks accurately after the numbers are greater than 3; and their performance gets worse the higher the numbers climb, but showed a constant coefficient of variation, which is suggestive of an analog estimation process^ref. Some believe that children and some animals are born with 2 basic types of 'counting' but that these are limited. First, they can recognize 1, 2 or 3 objects by recording an image in their memory. Second, they can make estimates of larger numbers, such as 'about 20'.
• new languages can develop consistent rules of grammar within a single generation of their birth, a study of an Israeli sign language has shown. The Al-Sayyid Bedouins, who live in Israel's Negev region, have a high rate of congenital deafness. In a population of about 3,500, roughly 150 people are deaf. The community, which was founded about 200 years ago, has developed its own sign language over the past 70 years, with no apparent outside influences. This is the first documented example of a language evolving from scratch in such isolation. Sentences in Al-Sayyid Bedouin sign language have a word order of 'subject, object, verb' (SOV), as in the phrase 'I apple give'. Israel's spoken languages, Arabic and Hebrew, use 'subject, verb, object' (SVO). The same goes for English, as in 'I give apple'. The discovery suggests that grammar appears early in the development of face-to-face languages. Written language can take centuries to develop consistent grammar. Speedy development in sign language has been seen before. Nicaraguan deaf people have adopted a common sign language over the past 25 years, since they were brought together in a specialist school system for the deaf. But the Al-Sayyid Bedouins are the first group to be studied that has developed a sign language with no outside influence. The language's rapid progress is impressive. This finding suggests that the human mind has the motive and means to create an expressive, grammatical language without requiring many generations of fine-tuning. But there is nothing remarkable about the contrast between the signers' SOV structure and the SVO grammar of Israel's spoken languages. Languages are split between the 2 and some switch from one to the other, as shown by archaic English phrases that use SOV, such as "With this ring, I thee wed." The simple structure of Al-Sayyid Bedouin sign language is an important convention that will allow later sophistication. The Al-Sayyid Bedouins can sign 'James Jan kiss' and know that James has kissed Jan, rather than the other way around. Once a language is unambiguous outside its immediate context, complicated rules about agreements between subjects and verbs are able to evolve. But it will take many generations for such further subtleties to emerge.
• affectivity : the capacity to feel emotions; the degree of responsiveness or susceptibility to emotional stimuli.
• a woman who cannot recognize fear in people's faces is causing neuroscientists to rethink theories of how our brains read emotions. Scientists have been testing the 38-year-old woman for more than a decade. She has a rare disease that has damaged both sides of her amygdala, the almond-shaped part of the brain that is known from imaging studies to be involved in recognizing facial expressions. The woman, known as SM, finds it very difficult to tell from facial expressions when another person is afraid, although she has no problem recognizing other emotions, such as happiness, sadness and anger. Originally, researchers thought this meant that different emotions are processed by distinct neural circuits in the brain. But new studies with SM suggest quite a different explanation^ref  : researchers showed SM photographs of various different facial expressions and asked her what emotion she thought the people were feeling. Researchers have done this many times before. But this time, to find the part of the faces on which SM was focusing, the team used a 'bubble test' in which only part of the face is revealed at a time. The researchers were intrigued to find that SM totally avoided looking at people's eyes. She discerned her information simply from looking around the nose and mouth. This was generally enough for her to identify emotions such as happiness or anger, where features such as a smile, or bared teeth, are important. But wide eyes are a particularly important component of a fearful expression. Because SM was only looking at the nose and mouth, she did not notice the eyes and concluded that the person was feeling neutral. First you have to look at the eyes, and then the brain has to make use of that information to figure out it's fear. When the researchers simply told SM to look at people's eyes, she did, and her ability to distinguish fear dramatically improved. She needed constant reminding, as otherwise she stopped looking at the eyes. But this ability to regain lost function simply through receiving the correct instructions is extremely unusual in patients with brain damage. It suggests that SM doesn't have a problem processing the visual cues at all. Instead the area she has damaged may tell us where and how to look. If our brains simply took in all the information around us, we would be completely overwhelmed : what's needed is selectivity of some kind, to decide what's important, and the amygdala is a critical component of such a mechanism. This new understanding could be used to help develop treatments for people with disorders such as autism, who find it difficult to read emotions and are known to focus abnormally on certain facial features. Giving them direct reminders of how to look at other people's faces could help them to improve their perception of social cues.
• fear : stathmin 1 / oncoprotein 18, an inhibitor of microtubule formation, as highly expressed in the lateral nucleus (LA) of the amygdala as well as in the thalamic and cortical structures that send information to the LA about the conditioned (learned fear) and unconditioned stimuli (innate fear). Whole-cell recordings from amygdala slices that are isolated from stathmin knockout mice show deficits in spike-timing-dependent long-term potentiation (LTP). The knockout mice also exhibit decreased memory in amygdala-dependent fear conditioning and fail to recognize danger in innately aversive environments. By contrast, these mice do not show deficits in the water maze, a spatial task dependent on the hippocampus, where stathmin is not normally expressed. Stathmin is required for the induction of LTP in afferent inputs to the amygdala and is essential in regulating both innate and learned fear^ref.

Web resources : Fear and the amygdala
• brain sexual differentiation and behavior :
• the classic view is that gonadal steroid hormones act directly to promote sex differences in neural and behavioral development. In particular, the actions of testosterone and its metabolites induce a masculine pattern of brain development, while inhibiting feminine neural and behavioral patterns of differentiation
• an alternative hypothesis is that genes, by directly inducing sexually dimorphic patterns of neural development, can influence the sexual differences between male and female brains : sing microarrays and RT-PCR, 54 candidate genes for differential sex expression have been detected, and at least 7 murine genes which show differential expression between the developing brains of male and female mice at stage 10.5 days post coitum (dpc), before any gonadal hormone influence, have been confirmed. The identification of genes differentially expressed between male and female brains prior to gonadal formation suggests that genetic factors may have roles in influencing brain sexual differentiation, refuting 30 years of scientific theory that sexuality is entirely determined by sexual steroid hormones. In facts, transgender persons possess normal hormonal levels and gender dysphoria—feeling that you have been born into the body of the wrong sex—could have biological origins^ref
• pregnant rats supped on water laced with soluble aspirin for 2 weeks around the time they gave birth. But as their sons matured, their sex drives didn't. The males were slower at initiating sex than normal littermates, taking 2-3 times longer to mount females. They were also less likely to penetrate females and less likely to ejaculate. Mothers took a dose each day that was equivalent to the dose a human would take for a headache. Newborn female rat pups injected with PGE₂ (sometimes given to infants with a particular type of heart defect) when grown up have a sexual behaviour similar to that of males, as they mounted other females and pretended to mate with them. PGE₂-treated female rats had more synapses in the brain area related to sexual function^ref
• the sexually dimorphic nucleus (SDN) is up to 7 times larger in male brains than in female. Sheep are one of the few animal models in which natural variations in male sexual preferences have been studied experimentally. Approximately 8% of rams exhibit sexual preferences for male partners (male-oriented rams) in contrast to most rams, which prefer female partners (female-oriented rams). The ovine sexually dimorphic nucleus (oSDN) is a cell group within the medial preoptic area/anterior hypothalamus of adult sheep that is significantly larger in adult rams than in ewes. In addition to a sex difference, the volume of the oSDN is 2 times greater in female-oriented rams than in male-oriented rams. The dense cluster of neurons that comprise the oSDN express cytochrome P450 aromatase. Aromatase mRNA levels in the oSDN are significantly greater in female-oriented rams than in ewes, whereas male-oriented rams exhibit intermediate levels of expression. Because the medial preoptic area/anterior hypothalamus is known to control the expression of male sexual behaviors, these results suggest that naturally occurring variations in sexual partner preferences may be related to differences in brain anatomy and capacity for estrogen synthesis.
• visual sexually arousing stimuli : men are generally more interested in and responsive to than are women and fMRI shows that the amygdala and hypothalamus are more strongly activated in men than in women when viewing identical sexual stimuli. This is true even when women reported greater arousal. Sex differences are specific to the sexual nature of the stimuli, are restricted primarily to limbic regions, and are larger in the left amygdala than the right amygdala. Men and women show similar activation patterns across multiple brain regions, including ventral striatal regions involved in reward. The amygdala mediates sex differences in responsiveness to appetitive and biologically salient stimuli; the human amygdala may also mediate the reportedly greater role of visual stimuli in male sexual behavior, paralleling prior animal findings^ref.
• in general it is estimated that just 23% of women are not faithful : genes alone do not determine whether somebody is likely to be unfaithful - much is down to social factors. But if one of a pair of twins had a history of infidelity, the chances her sister would also stray were about 55%.
• vasopressin receptor gene, which helps to regulate social behaviour and pair bonding, introduced directly into the brain of male meadow voles (Microtus pennsylvanicus) cause normally promiscuous rodents to lose their lust for the ladies. Increasing the number of vasopressin receptors in the ventral forebrain, a brain region known to regulate addiction and reward, gives an animal a sense of reward when it forms a close pair bond, so lecherous animals calm their errant ways^ref. The animals' brain chemistry and behaviour resembles that of their relative, the monogamous prairie vole (Microtus ochrogaster). These faithful creatures mate for life and have many vasopressin receptors in the ventral forebrain. Earlier work has shown that boosting vasopressin receptor levels speeds up pair bond formation in monogamous voles. Promiscuous and monogamous monkey species have different patterns of vasopressin receptor expression that closely match those seen in the voles, so it is possible that philandering and faithful humans may share similar brain chemistry, but pair bonding in humans is more complex : social factors, economics, history and individual differences all play a role.
• females prefer males who have been seen wooing a mate. Female zebra finches given a choice of 3 males (1 that the birds had seen in a cage with another female, and 2 that had been cooped up together) chose the previously paired male, even if he was not genetically better than the others
• activity : the state of being active; the ability to produce some effect; the extent of some function or action.
• ambidexterity : the ability to perform acts requiring manual skill with either hand, some ordinarily being performed with one and some with the other.
• behavior : deportment or conduct; any or all of a person's total activity, especially that which can be externally observed.
• sociobiology : the branch of theoretical biology which proposes that all animal (including human) behavior has a biological basis, which is controlled by the genes; the study of the biological basis of behavior.
• sociology : the science dealing with social relations and phenomena
• sociometry : the branch of sociology concerned with the measurement of human social behavior.
• automatic behavior / automatism : aimless and apparently undirected behavior that is not under conscious control and is performed without conscious knowledge; seen in psychomotor epilepsy, catatonic schizophrenia, dissociative fugue, and other conditions
• ambulatory automatism : a condition in which the patient walks about and performs acts mechanically and without consciousness of what he is doing.
• command automatism : the performance of suggested acts without exercise of critical judgment; seen in catatonic schizophrenia and in the hypnotic state.
• invariable behavior : activity whose character is determined by innate structure, such as reflex action.
• variable behavior : behavior that is modifiable by individual experience.
• classical, pavlovian or respondent conditioning or behavior : learning in which a stimulus initially incapable of evoking a certain response acquires the ability to do so by repeated pairing with another stimulus that does elicit the response
• aversive conditioning : learning in which punishment or other unpleasant stimulation is used to associate negative feelings with an undesirable response and so reduce the frequency of that response.
• operant or instrumental conditioning / operant behavior : learning in which the frequency of a particular voluntary response is altered by the application of positive or negative consequences
• avoidance conditioning : a form of operant conditioning in which an organism is trained to avoid certain responses or situations associated with negative consequences.
• aggressiveness : a lack of symmetry is known to be a hallmark of slightly imperfect development, so people with ill-matched external features may also have small defects in their nervous systems, which impair their ability to control aggressive impulses. Those with uneven ears, wrists, palms, ankles, feet and elbows  are more prone to angry reactions to stressful telephone conversations and replace the receiver more forcefully after the call. Female volunteers were more likely to be enraged by the rude call recipients. But male subjects slammed the phone down harder on the polite charity targets. So why did the men not become the most angry when faced with both rejection and rudeness? Men can become aggressive more quickly then women, but are also quicker to back down if things start to look hairy. They don't seem to be able to tolerate as much anger as women : men are much more attentive to their bodily state, such as heart-beat. Nevertheless, both sexes, no matter how symmetrical, can suffer unproductive attacks of rage. As a final part of the study, the researchers asked volunteers to select one of three follow-up letters to send to the charity targets. Subjects generally chose the harshest letter for the rude respondent, telling them that they were doing "a disservice to the community", which was hardly the best way to encourage future donations^ref.
• masculinity : a scientist set out to prove an old adage of pop psychology: men will overcompensate by acting excessively “manly” when their masculinity is threatened. But to do it, he had to play mind tricks on some unsuspecting men. It seems he got what he wanted. Men in his study were found to profess greater support of the Iraq war if they were told that their recent responses on a questionnaire marked them as “feminine” types. What they weren’t told was that this information about their masculinity had no factual basis. These men also voiced more anti-gay attitudes and greater willingness to buy a big car than other men. If you made men more insecure about their masculinity, they displayed more homophobic attitudes, tended to support the Iraq War more and would be more willing to purchase an SUV. Masculine overcompensation is the idea that men who are insecure about their masculinity will behave in an extremely masculine way as compensation. I wanted to test this idea and also explore whether overcompensation could help explain some attitudes like support for war and animosity to homosexuals. Willer administered a gender identity survey to a sample of male and female Cornell undergraduates in the fall of 2004. Participants were randomly assigned to receive feedback that their responses indicated either a masculine or a feminine identity. While women’s responses were unchanged regardless of the feedback they received, men’s reactions were strongly affected by this feedback. Masculinity-threatened men also reported feeling more ashamed, guilty, upset and hostile than did masculinity-confirmed men. The notion that masculinity-threatened men overcompensate is rooted in the theories of Sigmund Freud, the 19th-and early-20th century psychologist. The idea has become a common part of household wisdom, though, with the more pro-women’s-rights culture that has established itself in the the last few decades in Western societies. Nonetheless, the idea still hasn’t been properly tested. 111 Cornell undergraduate students were questioned about their political attitudes, including how they felt about a same-sex marriage ban and their support for President Bush’s handling of the Iraq War.  I created composites from subjects’ answers to these and other questions. I also gave subjects a car-buying vignette, presented as part of a study of purchasing a new car. Masculinity-threatened participants also showed more interest in buying an SUV. There were no increases for other types of cars. The study produced the predicted results. The intention of the study was to explore whether masculine overcompensation exists and where. But the point isn’t to suggest these are the only factors that can explain these behaviors. Likewise, there may be a wide variety of other behaviors that could increase when men are concerned about their levels of masculinity. Willer and a colleague are planning additional research on subjects’ attitudes regarding violence toward women, using the same method for manipulating masculine insecurity.  I’m planning another follow-up to the study that involves taking testosterone samples from participants to see if testosterone levels are a factor in this process.
• socialization : the process by which society integrates the individual, and the individual learns to behave in socially acceptable ways. Like many of us, sheep do not like being alone. They are also excellent at recognizing individual faces, and can remember the features of up to 50 sheep and 10 humans over a two-year period^ref. As soon as the animals were left alone, their heart rates began to soar. At the end of the first 15 minutes, adrenalin and stress hormone levels had increased, indicating clear signs of stress. But after 15 minutes of simulated sheep company, the animals became calmer. Heart rates fell to pre-isolation levels. Stress hormone and adrenaline levels more than halved, and the number of unhappy bleating noises dropped by 20-fold. Goat pictures produced intermediate effects, suggesting that sheep find photographs of their own species more comforting than those of other animals^ref
• social conformity—a desire to act, talk, dress and even think like everyone else—is a human tendency that has helped glue societies together for ages, while perennially irritating some of the greatest thinkers, scientists and artists.  Now, researchers have found we share this monkey-see-monkey-do mindset with—perhaps unsurprisingly—chimps. This shows conformity has deep evolutionary roots. During the study, 3 groups of chimps at the Yerkes National Primate Research Center of Emory University in Atlanta, Ga., were presented with a problem also known to their wild cousins: some enticing food was stuck just out of reach, behind a blockage. This was achieved by a system of tubes the researchers called the Pan-pipes. Unseen by their group-mates, one chimp from each of two of the groups was shown a different way to use a stick to retrieve the food. One was taught to use the tool to lift the blockage up so the food fell towards her. The other was trained instead to poke the blockage, pushing it so the food fell backwards and rolled down another pipe into her waiting hand. These 2 chimps, who were high-ranking members of their groups, were then reunited with their respective groups, the researchers recounted. They soon started to apply their newly-learned techniques to the Pan-pipes task. The researchers wanted to find out whether the other chimps would learn by observation the technique used by their local expert, and thus establish different traditions in the two groups. Chimpanzees in the wild show numerous local traditions described as ‘ape culture', but it is almost impossible to prove that these traditions are actually passed on by each chimpanzee learning from others, as is the case with humans. It is hard to do the necessary experiments with wild chimpanzees. The chimps in the experiment proved keen learners, according to the scientists. Members of the chimp groups gathered around their local experts, watched attentively and learned the technique. But this wasn’t true of the third group of chimps, which didn’t have the benefit of a local expert and was left to solve the task on its own. Its members couldn’t retrieve food from the pipes. In contrast, in the first experimental group the expert’s “lift” technique was soon adopted, while the “poke” method spread in the second group, the scientists said. When tested two months later, this difference in group traditions persisted, the researchers found. This is the first experimental evidence for the spread and maintenance of traditions in any primate, they claimed. Chimps copy members of their own species and they develop different traditions by doing so. It makes it likely differences in tool use between wild chimpanzee communities in Africa indeed reflect a form of culture and establishes another link between human and chimpanzee societies. A few members of each group independently discovered the alternative method for freeing food from the Pan-pipes. But this knowledge didn’t change group traditions: most of these chimps reverted to the norm set by their local expert. Choosing the group norm over the alternative method shows a level of conformity we usually associate only with our own species. These results suggest an ancient origin for the cultural conformism that is so evident in humans. Further research may reveal this tendency to be more widespread in the animal kingdom. The findings aren’t the only recent research to find unexpected commonalities between human and primate societies. These commonalities sometimes involve cultural tendencies that some of us view with contempt. For instance, one recent study concluded that monkeys may have a version of “celebrity-gazing” evident in humans. Monkeys in that study were found to prefer looking at higher-ranking members of their group, rather than lower-ranking ones. Interestingly, in the conformity study, the chimp chosen to be each group’s expert was a high-ranking female^ref.
• reward
• like many humans, monkeys tend to slack off when their goal is distant, then work harder as a deadline looms. When antisense D₂ gene is transfected into the rhinal cortex, the procrastinating  monkeys were unable to learning of cues that predict reward (how many trials were left before the reward was given) and became workaholics. They stopped procrastinating and worked hard throughout the task, making consistently fewer errors at every stage^ref. Depressed people, for example, commonly fail to find work rewarding. Sufferers of obsessive-compulsive disorder and bipolar disorder (also known as manic depression) often work frantically, sometimes for little reward.
• humor modulates the mesolimbic reward centers : cartoons activate the nucleus accumbens as cocaine, money or a pretty face
• neuroeconomics : deciding between a risky financial investment and a safe one sets two parts of the brain into competition. As centres for pleasure and anxiety battle it out, a simple brain scan of the 2 can actually predict what a person will chose to do a few seconds before they do it: when joy beats worry in our brain, a risky decision is made. Studies of how the mind handles risky behaviour have highlighted a number of neural hotspots. One is a peanut-sized region of the brain called the nucleus accumbens, which is loaded with the molecule dopamine and becomes active in anticipation of pleasure. The nucleus accumbens is known to play a role in the addictive affect of drugs. Another region, known as the anterior insula, is stimulated in anticipation of a bad sensation. This area lights up in those predicting the onset of physical pain, and in generally anxious individuals. Researchers sought to compare how these two brain regions interact by asking 20 volunteers to play an investment game for a cash reward. The participants pushed a computer button to select either a safe bond, which was guaranteed to earn them $1 in any given round, or one of two stocks. One stock had a 50% chance of earning the player $10 in a single round, and a 25% chance of losing him or her $10. The other carried a 50% chance of losing $10 and a 25% chance of winning it. But the scientists did not reveal which stock was which, making it an even riskier game to play. As the participants completed the task, a machine took snapshots using functional magnetic resonance imaging, which revealed the active parts of the brain. The results showed that the nucleus accumbens lit up about two seconds before a risky investment was made. When the anxious anterior insula was more active, the participants stuck to the safer choice. The results of this study, reveal a previously unknown interplay between these 2 brain regions. The thing to do is to work out when and why one part of our brain outdoes the other. The ultimate question is: when do you listen to one circuit and not the other? The answer might help everyone from psychologists aiming to dull anxiety in nervous patients, to marketing gurus attempting to get customers to live dangerously^ref
• temperament : an inherent, constitutional predisposition to react to stimuli in a certain way. The term is often used synonymously with personality
• character : in psychiatry, a term used, especially in the psychoanalytic literature, in much the same way as personality, particularly for those personality traits that are shaped by life experiences and developmental processes
• personality : the characteristic way that a person thinks, feels, and behaves; the relatively stable and predictable part of a person's thought and behavior; it includes conscious attitudes, values, and styles as well as unconscious conflicts and defense mechanisms. It results from combination of temperament and character.
• personality type : any of various categories of both normal and abnormal personality variants; usually they derive from a theory-based topology, such as introvert/extrovert or oral/anal/phallic.
• mood : a pervasive and sustained emotion that, when extreme, can color one's whole view of life and markedly affect behavior. Mood is generally used to refer to either elation or depression
CNS neurobiology :
• the brains of mice lacking CREST appear normal at birth, but do not develop normally in response to sensory experience after birth : this is similar to learning disorders in humans where children appear normal initially but by age of 2-3 are failing to properly acquire new knowledge. The CREST protein produced by the gene is made in several regions of the brain immediately after birth. In adults, CREST is produced in the hippocampus, an area of the brain that's important for learning and memory
• symmetricity of the 2 hemispheres of the brain is greater in females than in males : symmetry may improve communication between both sides of the brain—an anatomical difference that may explain why women can sometimes articulate their feelings more easily than men.
• 91 genes are expressed in different amounts in cerebral cortex from humans compared to chimpanzees and rhesus monkeys : 83 of these genes showed higher levels of activity in humans. The changes in gene activity in the cortex suggest increases in the rate of brain activity, providing a basis for the evolution of the enhanced cognitive abilities in humans. The human brain has increased expression of genes that protect against activity-related damage, which may explain why humans generally live longer than other primates and why humans are especially vulnerable to age-related neurodegenerative diseases such as Alzheimer's.
Reducing the size of an organ, such as the brain, while maintaining adequate function is usually beneficial. A smaller brain requires fewer materials and less energy for construction and maintenance, lighter skeletal elements and muscles for support, and less energy for carriage. The size of a nervous system can be reduced by reducing the number of neurons required for adequate function, by reducing the average size of neurons required for adequate function, by reducing the average size of neurons, or by laying out neurons so as to reduce the lengths of their connections. Just like the wires connecting components in electronic chips, the connections between neurons occupy a substantial fraction of the total volume, and the wires (axons and dendrites) are expensive to operate because they dissipate energy during signaling. Nature has an important advantage over electronic circuits because components are connected by wires in 3D space, whereas even the most advanced very large scale integration (VLSI) microprocessor chip use a small number of layers of planar wiring (a recently produced chip with 174 million transistors has 7 layers). Does 3D wiring explain why the volume fraction of wiring in the brain (40 to 60%) is lower than in chips (up to 90%) ? In chips, the components are arranged to reduce the total length of wiring. This same design principle has been established in the nematode worm Caenorhabditis elegans, which has 302 neurons arranged in 11 clusters called ganglia. An exhaustive search of alternative ganglion placements shows that the layout of ganglia minimizes wire length. Cortical projections in the early sensory processing areas are topographically organized. This is a hallmark of the 6-layer neocortex, in contrast to the more diffuse projections in older 3-layer structures such as the olfactory cortex and the hippocampus. In the primary visual cortex, for example, neighboring regions of the visual field are represented by neighboring regions in the cortex. Connectivity is much higher between neurons separated by less than 1 mm than between neurons farther apart, reflecting the need for rapid, local processing within a cortical column - an arrangement that minimizes wire length. Because cortical neurons have elaborately branched dendritic trees (which serve as inpuit regions) and axonal trees (which project the output to other neurons), it is also possible to predict the optimal geometric patterns of connectivity, including the optimal ratios of axonal to dendritic arbor volumes. These conclusions were anticipated nearly 100 years ago by the great neuroanatomist Ramon y Cajal : "After the many shapes assumed by neurons, we are now in a position to ask whether this diversity ... has been left to chance and is insignificant, or whether it is thightly regulated and provides an advantage to the organism... We realized that all of the various conformations of the neurons and its various components are simply morphological adaptations governed by laws of conservation for time, space, and material". The conservation of time is nicely illustrated in the gray matter of the cerebral cortex. Gray matter contains the synapses, dendrites, cell bodies, and local axons of neurons, and these structures form the neural circuits that process information. About 60% of the gray matter is composed of axons and dendrites, reflecting a high degree of local connectivity analogous to a local area network. An ingenious analysis of resource allocation suggests that this wiring fraction of 60% minimizes local delayes. This fraction strikes the optimum balance between 2 opposing tendencies : transmission speed and component density. Unlike the wirse in chips, reducing the diameter of neural wires reduces the speed at which signals travel, prolonging delays. But is also reduces axon volume, and this allows neurons to be packed closer together, thus shortening delays. Long-range connections between cortical areas constitute the white matter and occupy 44% of the cortical volume in humans. The thickness of gray matter, just a few millimeters, is nearly constant in species that range in brain volume over 5 orders of magnitude. The volume of the white matter scales approximately as the 4/3 power of the volume of the gray matter, which can be explained by the need to maintain a fixed bandwidth of long-distance communication capacity per unit area of the cortex. The layout of cortical areas minimizes the total lengths of the axons needed to join them. The prominent folds of the human cortex allow the large cortical area to be packed in the skull but also allow cortical areas around the convolution to minimize wire length; the location of the folds may even arise from elastic forces in the white matter during development. The global connectivity in the cortex is very sparse, and this too reduces the volume occupied by long-range connections.: the probability of any 2 cortical neurons having a direct connetion is around 1% for neurons in a vertical column 1 mm in diameter, but is 1 in 1,000,000 for distant neurons. The distribution of wire lengths on chips follows an inverse power law, so that shorter wires also dominate. If we created a matrix with 10¹⁰ rows and columns to represent the connections between every pair of cortical neurons, it would have a relatively dense set of entries around the diagonal but would have onlyu sparse entries outside the diagonal, connecting blocksof neurons corresponding to cortical areas. The sparse long-range connectivity of the cortex may offer some of the advantages of small-world connectivity. Thus, only a small fraction of the computation that occurs locally can be reported to other areas, through a small fraction of the cells that connect distant cortical areas; but this may be enought to achieve activity that is coordinated in distant parts of the brain, as reflected by the synchronous firing of action potentials in these areas, supported by massive feedback projections between cortical areas and reciprocal interactions with the thalamus. Despite the sparseness of the cortical connection matrix, the potential bandwidth of all of the neurons in the human cortex is around a terabit per second (assuming a maximum rate of 100 bits/s over each axon in the white matter), comparable to the toal world backbone capacity of the Internet in 2002. However, this capacity is never achieved in practice because only a fraction of cortical neurons have a high rate of firing at any given time. Recent work suggests that another physical constraints - the provision of energy - limits the brain's ability to harness its potential bandwidth. As the processor speeds of computers increase, the energy dissipation increases, so that cooling technology becomes critically important. Energy consumption also constraints neural processing. Nervous systems consume metabolic energy continuously at relatively high rates per gram, comparable to those of heart muscle. Consequently, powering a brain is a major drain on an animal's energy budget, typically 2 to 10% of the resting energy consumption. In humans this proportion is 20% for adults and 60% for infants, which suggests that the brain's energy demands limit its size. Energy supply limits signal traffic in the brain. Deep anesthesia blocks neural signaling and halves the brain's energy consumption, which suggests that about 50% of the brain's energy is used to drive signals along axons and across synapses. The remainder supports the maintenance of resting potentials and the vegetative function of neurons and glia. Cortical gray matter uses a higher proportion of total energy consumption for signaling, more than 75%, because it is so richly interconnected with axons and synapses. From the amouts of energy used when neurons signal, one can calculate the volume of signal traffic that can be supported by the brain's metabolic rate. For cerebral cortex, the permissible traffic is 5 action potentials per neuron per second in rat and < 1 per second in human. Given that the brain responds quickly, the permissible level of traffic is remarkably low, and this metabolic limit must influence the way in which information is processed. Recent work suggests that brains have countered this sever metabolic constraint by adopting energy-efficient designs. These designs involve the miniaturization of components, the elimination of superfluous signals, and the representation of information with energy-efficient codes. The observation that 1 mm³ of mouse cortex contains 10⁵ neurons, 10⁸ synapses, and 4 km of axon suggests that, as in chip design, the brain reduces energy consumption by reducing the sixe and active area of components. Even though axon diameter is only 0.3 mm (on average), sending action potentials along these wires consumes more than one-third of the energy supplied to cortical gray matter. Thus, as with computer chips, an efficient layout and a high component density are essential for energy efficiency - but, as is also true for chips, miniaturization raises the problems about noise. When a neuron's membrane area is reduced, the number of molecular pores (ion channels) carrying electrical current falls, leading to a decline in the signal-to-noise ratio (SNR). The noise produced by ion channels, and by other molecular signaling mechanisms such as synaptic vesicles, is potentially damaging to performance. However, the effects of noise are often difficult to determine beacuse they depend on interactions between signaling molecuels in signaling systems. These interactions can be highly nonlinear (e.g. the voltage-dependent interactions between sodium and potassium ion channels that produce action potentials) and can involve complicated spatial effects (e.g. the diffusion of chemical messengers between neurons and the transmission of electrical signals within neurons). A new generation of stochastic simulators is being developed to handle these complexities and determine the role played by molecular noise and diffusion in neural signaling. With respect to miniaturization, stochastic simulation show that channel noise places a realistic ceiling on the wiring density of the brain by setting a lower limit of about 0.1 mm on axon diameter. The buildup of noise from stage to stage may be a fundamental limitation on the logical depth to which brains can compute. The analysis of the relationships among signal, noise, and bandwidth and their dependece on energy consumption will play a central role in understanding the design of neural circuits. The cortex has many of the hallmarks of an energy-efficient hybrid device. In hybrid electronic devices, compact analog models operate on signals to process information, and the results are converted to digital data for transmission through the network and then  reconverted to analog data for further processing. These hybrids offer the ability of analog devices to perform basic arithmetic functions such as division directly and economically, combined with the ability of digital devices to resist noise. In the energy-efficient silicon cochlea, for example, the optimal mix of analog and digital data (that is, the size and number of operations performed in analog modules) is determined by a resource analysis that quantifies trade-offs among energy consumption, bandwidth for information tranmission, and precision in analog and digital components. The obvious similarities between hybrid devices and neurons strongly siggest that hybrid processing makes a substantial contribution to the energy efficiency of the brain. However, the extent to which the brain is configured as an energy-efficient hybrid device imust be establuished by a detailed resource analysis that is based on biophysical relationships among energy consumption, precision, and bandwidth in neurons. Some research strongly suggets that noise makes it uneconomical to transfer information down single neurons at high rates. Given that a neuron is a noise-limited device of restricted bandwidth, the information rate is improved with the SNR, which increases as the square root of the number of ion channels, making improvements expensive. Thus, doubling the SNR means quadrupling the number of channels, the current flow, and hence the energy cost. Given this relationship between  noise and energy cost, an energy-efficient nervous system will divide information among a large number of relatively noisy neurons of lower information capacity, as observed in the splitting of retinal signals into ON and OFF pathways. Perhaps the unreliability of individual neurons is telling us that the brain has evolved to be energy efficient. Energy efficiency is improved when one reduces the number of signals in the network without losing information. In the nervous system, this amounts to an economy of impulses that has additional advantage of increasing salience by laying out information concisely. Economy is achieved by eliminating redundancy. This important design principle is well established in sensory processing. Redundancy reduction is a goal of algorithms that compress files to reduce network traffic. In the brain, efficiency is improved by distributing signals appropriately in time and space. Individual neurons adopt distributions of firing rate. that maximize the ratio between information coded and energy expended. Networks of neurons achieve efficiency by distributing signals sparsely in space and time. Although it was already recognized that sparse coding improves energy efficiency, it was Levy and Baxter's detailed analysis of this problem that initiated theoretical studies of energy-efficient coding in nervous systems. They compared the representational capacity of signals distributed across a population of neurons with the costs involved. Sparse coding schemes, in which a small proportion of cells signal at any one time, use little energy for signaling but have a high representational capacity, because there are many different ways in which a small number of signals can be distributed along a large number of neurons. However, a large population of neurons could be expensive to maintain, and if these neurons rarely signal, they are redundant. The optimum proportion of active cells depends on the ratio between the cost of maintaining a neuron at rest and the extra cost of sending a signal. When signals are relatively expensive, it is best to distribute a few of them among a large number of cells. When cells are expensive, it is more efficient to use few of them and to get all of them signaling . Estimates of the ratio between the energy demands of signaling and maintenance suggest that, for maximum efficiency, between 1% and 16% of neurons should be active at any one time. However, it is difficult to compare these predictions with experimental data; a major problem confronting systems neuroscience is the development of techniques for deciphering sparse codes. There is an intriguing possibility that the energy efficiency of the brain is improved by regulating signal traffic at the level of the individual synaptic connection betwen neurons. A typical cortical neuron receives on the order of 10,000 synapses, but the probability that a synapse fails to release neurotransmitter in response to an incoming signal is remarkably high, between 0.5 and 0.9. Synaptic failures halve the energy consumption of gray matter, but because there are so many synapses, the failures do not necessarily lose information. The minimum number of synapses required for adequate function is not known. Does the energy-efficient cortical neuron, like the wise Internet user, select signals from sites that are most informative? This question draws energy efficiency into one of the most active and important areas of neuroscience : synaptic plasticity. Long-distance communicatgion in the brain occurs through all-or-none action potentials, which are transmitted down axons and converted to analog chemical and electrical signals at synapses. The initiation of action potentials in the cortex can occur with millisecond precision but the communication at cortical synapses is probabilistic. On a short time scale of millisecond to seconds, presynaptic mechanisms briefly increase or decrease the probability of transmission at cortical synapses over a wide range, depending on the previous patterns of activity. On longer time scales, persistent correlated firing between the presynaptic and postsynaptic neurons can produce long-term depression or potentiation of the synaptic efficacy, depending on the relative timing of the spikes in the 2 neurons. A new view of the cortical network is emerging from these discoveries. Rather than being a vast, fixed network whose connection strengths change slowly, the effective cortical connectivity is highly dynamic, changing on fast as well as slow time scales. This allows the cortex to be rapidly reconfigured to meet changing computational and communications needs. Unfortunatey, we do not yet have techniques for eaves-dropping on a large enough number of neurons to determine how global reconfiguration is achieved. Local field potentials (LFPs), extracellular electric fields that reflect the summed activity from local synaptic currents and other ion channels on neurons and glial cells, may provide hints of how the flow of information in cortical circuits is regulated. Oscillations in the 20- to 80-Hz range occur in the LFPs, and the coherence between spikes and these oscillations has been found to be influenced by attention and working memory.
• Mierzejewski effect : the disharmonious development of gray and white matter of the brain, the gray being in excess.

Cortical white and gray matter volumes of 59 mammalian species are related by a power law that spans 5 to 6 orders of magnitude. The line is the least squares fit, with a slope around 1.23+/- 0.01 (mean +/- SD) and correlation of 0.998. The number of white matter fibers is proportional to the gray matter volume.; their average length is the cubic root of that volume. If the fiber cross section is constant, then the white matter volume should scale approximately as the 4/3 power of the gray matter volume. An additional factor arises from the cortical thickness, which scales as the 0.10 power of the gray matter volume.
The size of human brain tripled over a period of approximately 2 million years (MY) that ended 0.2-0.4 MY ago. This evolutionary expansion is believed to be important to the emergence of human language and other high-order cognitive functions, yet its genetic basis remains unknown. Abnormal spindle-like microcephaly associated (ASPM) is a gene controlling brain development, as nonsense mutations lead to primary microcephaly, a human disease characterized by a 70% reduction in brain size. Human ASPM went through an episode of accelerated sequence evolution by positive Darwinian selection after the split of humans and chimpanzees but before the separation of modern non-Africans from Africans. A German border collie has surprised scientists with his 200-word vocabulary and uncanny knack for learning new words, shedding light on the evolution of language. 9-year-old Rico knows the names of each toy in his hundred-strong collection and can retrieve items called out to him with over 90% accuracy^{ref1, ref2}. He can also learn and remember the names of unfamiliar toys after just one encounter, putting him on a par with a 3-year-old child. But canines' ability to comprehend speech can only have manifested itself after they were domesticated, some 15,000 years ago, and human speech is thought to have evolved 100,000 to 200,000 years ago : the ability to match novel words and items has evolved twice, first in humans and then in dogs.
Web resources :
• Associations :
• Cognitive Neuroscience Society (CNS)
• Cognitive Science Society
• European Brain and Behaviour Society (EBBS)
• Cognitive Neuroscience Resources by the Center for the Neural Basis of Cognition
• Cognitive and Psychological Sciences on the Internet
• Centre de Recherche in Neurosciences Cognitives (CNRS)
• Department of Cognitive and Neural Systems at Boston University
• European Institute of Cognitive Sciences and Engineering (EURISCO)
• Full-text original papers on mind
• The Brain From Top to Bottom, created by neuroscientist Bruno Dubuc of the Canadian Institutes of Health Research
• The Virtual Library - Psychology
• The Virtual Library - Stress
• Usenet sci.med.psychobiology
• peripheral nervous system (PNS) / pars peripherica systematis nervosi / systema nervosum periphericum (see also pathology of the peripheral nervous system): the peripheral part of the nervous system, consisting of the nerves and ganglia outside the brain and spinal cord
• nerve / nervus : a cordlike structure made up of a collection of fibers that convey impulses between a part of the CNS and some other region of the body. A nerve consists of a connective tissue sheath (epineurium) enclosing bundles of fibers (funiculi or fasciculi); each bundle is in turn surrounded by its own sheath of connective tissue (perineurium), the inner surface of which is formed by a membrane of flattened mesothelial cells. Very small nerves may consist of only one funiculus derived from the parent nerve. Within each such bundle, the individual nerve fibers, which are microscopic in size, are surrounded by interstitial connective tissue (endoneurium). An individual nerve fiber (an axon with its covering sheath) consists of formed elements in a matrix of protoplasm (axoplasm), the entire structure being enclosed in a thin membrane (axolemma). Each nerve fiber is enclosed by a cellular sheath (neurilemma), from which it may or may not be separated by a lipid layer (myelin sheath) derived from neurilemmal cells
• anelectrotonic state : the condition which occurs in a nerve near the anode during the passage of a continuous current
• catelectrotonic state : the condition of a nerve near the cathode during the passage of an electric current.
• ganglion : a general term for a group of nerve cell bodies located outside the CNS; occasionally applied to certain nuclear groups within the brain or spinal cord, e.g., basal ganglia.
• capsula ganglii / capsule of ganglion : the laminated connective tissue capsule surrounding a neural ganglion and continuous with epineurium of its associated nerve root.
Cell types :
• Schwann cell : any of the large nucleated cells whose cell membrane spirally enwraps the axons of myelinated peripheral neurons and is the source of myelin; a single Schwann cell supplies the myelin sheath between 2 nodes of Ranvier
• satellite cell
• Beale's ganglion cells : bipolar cells with one process coiled around the other; found in cardiac ganglia.
Anatomy :
• nervi craniales or encephalici / cranial, cerebral or encephalic nerves : the 12 pairs of nerves that are connected with the brain
• nucleus nervi cranialis / nucleus of cranial nerve : any of the nerve cells in the central nervous system that give rise to, or transmit or receive impulses from, the motor and sensory components of the cranial nerves
• nucleus originis / nucleus of origin : any of the groups of nerve cells in the CNS from which arise the motor, or efferent, fibers of the cranial nerves.
• olfactory nerve / nervus olfactorius (I) : the central processes of the olfactory receptor cells, or fila olfactoria, considered collectively
• fila olfactoria / olfactory nerves (1st cranial) : the nerves of smell, consisting of about 20 bundles which arise in the olfactory epithelium and pass through the cribriform plate of the ethmoid bone to the olfactory bulb.
• bulbus olfactorius / olfactory bulb / Morgagni's tubercle : the bulblike expansion of the olfactory tract on the under surface of the frontal lobe of each cerebral hemisphere; the olfactory nerves enter it
• mitral cells : neurons with pyramidal bodies located in the olfactory bulb, being the second stage in the pathway to the cortex; they receive impulses in the olfactory glomeruli from the olfactory cells and transmit impulses through the olfactory tracts to various areas of the cortex.
• periglomerular cells : nerve cells in the olfactory bulb that have synaptic connections with glomeruli, mitral cells, and tufted cells, and are thought to act as dampers
• tufted cells : a type of cell in the olfactory bulb, smaller, more numerous, and more superficially located than a mitral cell but with similar functions and connections.
• tractus olfactorius / olfactory tract : a narrow triangular band in the olfactory sulcus of the frontal lobe, which arises from the olfactory bulb and extends posteriorly, to end by dividing into medial and lateral olfactory striae, the latter ending in the primary olfactory cortex.
• optic nerve / nervus opticus (II) : actually part of the CNS throughout its course, misnamed as a nerve because of its cordlike appearance; it consists chiefly of axons and central processes of cells of the ganglionic layer of the retina, which leave the orbit through the optic canal, and joins with its opposite number to form the optic chiasm (the medial fibers of each nerve crossing over to the opposite side), then continues as the optic tractto end in the lateral geniculate body.
• radix lateralis tractus optici / lateral root of optic tract : fibers from the optic tract that enter the lateral geniculate body
• radix medialis tractus optici / medial root of optic tract : fibers from the optic tract that enter the superior colliculus and the pretectal region
• (common) oculomotor nerve / nervus oculomotorius (III) :
• origin : nucleus nervi oculomotorii

Emerging medial to cerebral peduncles and running forward in the cavernous sinus
• branches : superior and inferior rami
• distribution : entering the orbit through the superior orbital fissure, the branches supply the levator palpebrae superioris, medial rectus muscle of eye, superior rectus muscle, inferior rectus muscle, smaller or inferior oblique muscle, and carry parasympathetic fibers for the ciliary muscle and sphincter pupillae
• modality : motor and parasympathetic.
• pathetic or trochlear nerve / nervus trochlearis (IV) :
• origin : nucleus nervi trochlearis; the fibers of each trochlear nerve (one on either side) decussate across the median plane and emerge from the back of the brain stem below the corresponding inferior colliculus
• distribution : runs forward in lateral wall of cavernous sinus, traverses the superior orbital fissure, and supplies greater or superior oblique muscle of eyeball
• modality : motor
• trigeminal nerve / nervus trigeminus (V)
• nuclei of trigeminal nerve : 4 nuclei located along the trigeminal nerve, chiefly in the pons and medulla oblongata but also extending as far down as the upper cervical spinal cord
• nucleus mesencephalicus nervi trigemini
• tractus mesencephalicus nervi trigeminalis / tractus mesencephalicus nervi trigemini / mesencephalic tract of trigeminal nerve : a group of sensory fibers of the entering trigeminal nerve that continues rostrally along the medial aspect of the superior cerebellar peduncles; their cell bodies are located in the nucleus of the mesencephalic tract.
• nucleus motorius nervi trigemini
• nucleus principalis nervi trigemini
• nucleus spinalis nervi trigemini
• tractus spinalis nervi trigeminalis / tractus spinalis nervi trigemini / spinal tract of trigeminal nerve : a descending tract of the trigeminal nerve that extends from the level of entrance of the sensory root of the trigeminal nerves into the pons to the upper cervical segments of the spinal cord. Lying lateral to the nucleus of the spinal tract of the trigeminal nerve, in which its fibers synapse, this tract carries mainly pain and temperature impulses from the face.
It emerges from the lateral surface of the pons as :
• radix motoria nervi trigemini / motor root of trigeminal nerve : the smaller of the two roots by which the trigeminal nerve is attached to the side of the pons; it contains proprioceptive as well as motor fibers, and continues deep to the trigeminal ganglion to join the mandibular nerve
• some intermediate fibers
• radix sensoria nervi trigemini / sensory root of trigeminal nerve : the larger of the two roots by which the trigeminal nerve is attached to the side of the pons. It contains sensory fibers and expands into a large flat ganglion (the trigeminal ganglion) which gives rise to the ophthalmic, maxillary, and mandibular nerves.
• ganglion of trigeminal nerve / ganglion trigeminale / Gasser's ganglion / gasserian, semilunar or trigeminal ganglion : a ganglion on the sensory root of the fifth cranial nerve, situated in a cleft within the dura mater (trigeminal cave) on the anterior surface of the petrous portion of the temporal bone, and giving off the ophthalmic and maxillary and part of the mandibular nerve; it contains the cells of origin of most of the sensory fibers of the trigeminal nerve
• ophthalmic nerve / nervus ophthalmicus / ophthalmic division of trigeminal nerve
• origin : trigeminal ganglion
• branches :
• tentorial rami
• nervus frontalis / frontal nerve : enters the orbit through the superior orbital fissure; branches :
• nervus supraorbitalis / supraorbital nerve : branches, lateral and medial rami; distribution, leaves orbit through supraorbital notch or foramen, and supplies the skin of upper eyelid, forehead, anterior scalp (to vertex), mucosa of frontal sinus; modality, general sensory
• nervus supratrochlearis / supratrochlear nerve : distribution, leaves orbit at medial end of supraorbital margin and supplies the forehead and upper eyelid; modality, general sensory.
...; distribution, chiefly to the forehead and scalp; modality, general sensory.
• nervus lacrimalis / lacrimal nerve : entering the orbit through the superior orbital fissure; distribution, lacrimal gland, conjunctiva, lateral commissure of eye, and skin of upper eyelid; modality, general sensory.
• nervus nasociliaris / nasociliary nerve : branches :
• nervi ciliares longi / long ciliary nerves : distribution, dilator pupillae, uvea, cornea; modality, sympathetic and general sensory.
• nervus ethmoidalis anterior / anterior ethmoidal nerve : continuation of nasociliary nerve; branches, internal, external, lateral, and medial rami; distribution, mucosa of upper and anterior nasal septum, lateral wall of nasal cavity, skin of lower bridge and tip of nose; modality, general sensory.
• nervus ethmoidalis posterior / posterior ethmoidal nerve : distribution, mucosa of posterior ethmoid cells and of sphenoidal sinus; modality, general sensory
• nervus infratrochlearis / infratrochlear nerve : branches, palpebral rami; distribution, skin of root and upper bridge of nose and lower eyelid, conjunctiva, lacrimal duct; modality, general sensory
• a communicating branch to the ciliary ganglion
...; modality, general sensory.
• distribution : runs forward in lateral wall of cavernous sinus, eyeball and conjunctiva, lacrimal gland and sac, nasal mucosa and frontal sinus, external nose, upper eyelid, forehead, and scalp
• modality : general sensory
• maxillary nerve / nervus maxillaris / maxilary division of  trigeminal nerve, passing through the foramen rotundum, and entering the pterygopalatine fossa
• origin : trigeminal ganglion
• branches :
• meningeal ramus
• nervus zygomaticus / zygomatic nerve : entering the orbit through the inferior orbital fissure; branches :
• zygomaticofacial ramus
• zygomaticotemporal ramus
..., distribution, communicates with the lacrimal nerve and supplies the skin of the temple and adjacent part of the face; modality, general sensory.
• posterior superior alveolar rami
• infraorbital nerve
• pterygopalatine nerve
• indirectly, the branches of the pterygopalatine ganglion
• distribution : extensive distribution to skin of face and scalp, mucous membrane of maxillary sinus and nasal cavity, and teeth
• modality : general sensory
• mandibular nerve / nervus mandibularis / mandibular division of trigeminal nerve, passing through the foramen ovale to the infratemporal fossa
• origin : trigeminal ganglion
• branches :
• meningeal ramus
• nervus massetericus / masseteric nerve : distribution, masseter muscle and temporomandibular joint; modality, motor and general sensory.
• nervi temporales profundi / deep temporal nerves : usually 2 in number, anterior and posterior, with a third middle one often seen; distribution, temporal muscles; modality, motor.
• nervus pterygoideus lateralis / lateral pterygoid nerve : distribution, lateral pterygoid muscle; modality, motor
• nervus pterygoideus medialis / medial pterygoid nerve : distribution, medial pterygoid, tensor tympani, and tensor veli palatini muscles; modality, motor.
• nervus buccalis / buccal nerve : distribution, skin and mucous membrane of cheeks, gums, and perhaps the first two molars and the premolars; modality, general sensory
• nervus auriculotemporalis / auriculotemporal nerve : origin, by two roots from the mandibular nerve; branches :
• nervi auriculares anteriores / anterior auricular nerves : distribution, skin of anterosuperior part of external ear; modality, general sensory
• nervus meatus acustici externi / nerve of external acoustic meatus : distribution, skin lining external acoustic meatus, and tympanic membrane; modality, general sensory.
• parotid branches
• branch to tympanic membrane
• branches communicating with facial nerve
...; its terminal branches are superficial temporal to the scalp; modality, general sensory.
• nervus lingualis / lingual nerve : descending to the tongue, first medial to the mandible and then under cover of the mucous membrane of the mouth; branches :
• nervus lingualis / lingual nerve : descending to the tongue, first medial to the mandible and then under cover of the mucous membrane of the mouth; branches :
• nervus sublingualis / sublingual nerve : distribution, sublingual gland and overlying mucous membrane; modality, parasympathetic and general sensory
• lingual ramus
• ramus to the isthmus of the fauces
• rami communicating with the hypoglossal nerve and chorda tympani
...; modality, general sensory
• nervus alveolaris inferior / inferior alveolar nerve : origin, mandibular nerve; branches :
• nervus mylohyoideus / mylohyoid nerve / nerve to mylohyoid : distribution, mylohyoid muscle, anterior belly of digastric muscle; modality, motor
• inferior dental
• nervus mentalis / mental nerve : branches, mental, gingival, and inferior labial rami; distribution, skin of chin, and lower lip; modality, general sensory.
• inferior gingival nerve
...; modality, motor and general sensory.
• modality : general sensory and motor
• abducens nerve / nervus abducens (VI)
• origin : nucleus nervi abducentis, emerging from the brain stem anteriorly between the pons and medulla oblongata
• distribution : runs forward in lateral wall of cavernous sinus, lateral rectus muscle of eye
• modality : motor
• facial nerve / nervus facialis / nervus intermediofacialis (VII) :
• origin : inferior border of pons, between olive and inferior cerebellar peduncle, consisting of 2 roots
• a large motor root from nucleus motorius nervi facialis, which supplies the muscles of facial expression
• branches :
• upper temporofacial branch
• orbicularis oculi muscle
• nervus stapedius / stapedius nerve : distribution, stapedius muscle; modality, motor
• nervus auricularis posterior / posterior auricular nerve : branches, occipital ramus; distribution, auricularis posterior and occipitofrontalis muscles and skin of external acoustic meatus; modality, motor and general sensory.
• parotid plexus
• digastric ramus
• temporal ramus
• zygomatic ramus
• lower cervicofacial branch
• buccal ramus (orbicularis oris and mentonier muscles)
• lingual ramus
• marginal mandibular ramus
• cervical ramus
• communicating ramus with the tympanic plexus
• distribution
• modality : motor, parasympathetic, general sensory, special sensory
• a smaller root, the nervus intermedius / Wrisberg's intermediate nerve, lying between the main root and the vestibulocochlear nerve; it joins the main root at, or merges with, the geniculate ganglion at the geniculum of the facial nerve
• branches :
• radix parasympathica ganglii sublingualis / radix parasympathica ganglii submandibularis / chorda tympani. NOTE: when considering the ganglia of the pars parasympathica, this is the preferred term in the official nomenclature.
• nervus petrosus major / greater petrosal nerve / radix parasympathica ganglii pterygopalatini (which is the term preferred in the official nomenclature when the ganglia of the pars parasympathica are being considered) / radix intermedia ganglii pterygopalatini / parasympathetic root of pterygopalatine ganglion : origin, intermediate nerve via geniculate ganglion; distribution, running forward from the geniculate ganglion, it joins the deep petrosal nerve of the pterygoid canal, and reaches lacrimal, nasal, and palatine glands and nasopharynx, via pterygopalatine ganglion and its branches; modality, parasympathetic and general sensory
• distribution : lacrimal, nasal, palatine, submandibular, and sublingual glands, and anterior 2/3 of tongue (taste)
• modality : parasympathetic and special sensory.
• genu nervi facialis / genu of facial nerve : the bend in the fibers arising from the nucleus of the facial nerve, which produces the facial colliculus in the floor of the fourth ventricle; it is at this point that the fibers loop around the abducens nucleus.
• plexus intraparotideus / parotid plexus / plexus parotideus : a plexus formed by anastomosis of the terminal branches of the temporal, zygomatic, buccal, marginal mandibular, and cervical rami of the facial nerve, arising in the parotid gland
• vestibulocochlear nerve / nervus vestibulocochlearis / nervus acusticus / acoustic nerve (VIII) emerges from the brain between the pons and the medulla oblongata, at the cerebellopontine angle and behind the facial nerve. It divides near the lateral end of the internal acoustic meatus into 2 functionally distinct and incompletely united components, the vestibular nerve and the cochlear nerve, and is connected with the brain by corresponding roots :
• radix cochlearis or inferior nervi vestibulocochlearis : the central continuation of the cochlear nerve from the spiral ganglion, passing dorsal to the inferior cerebellar peduncle to enter the brain
• nervus cochlearis / cochlear nerve / pars cochlearis nervi octavi / pars cochlearis nervi vestibulocochlearis : the part of the vestibulocochlear nerve concerned with hearing, consisting of fibers that arise from the bipolar cells in the spiral ganglion and have their receptors in the spiral organ of the cochlea
• radix vestibularis or superior nervi vestibulocochlearis / superior or vestibular root of vestibulocochlear nerve : the central continuation of the vestibular nerve from the vestibular ganglion, entering the brain, just lateral to the intermediate nerve and in front of the inferior cerebellar peduncle
• nervus vestibularis / vestibular nerve / pars vestibularis nervi octavi or vestibulocochlearis : the posterior part of the vestibulocochlear nerve, which is concerned with equilibration. It consists of fibers arising from bipolar cells in the vestibular ganglion, and divides peripherally into a rostral and a caudal part, with receptors in the ampullae of the semicircular canals, the utricle, and the saccule
• nervus ampullaris anterior / anterior ampullar nerve : the branch of the vestibular nerve that innervates the ampulla of the anterior semicircular duct, ending around the hair cells of the ampullary crest.
• nervus ampullaris lateralis / lateral ampullar nerve : the branch of the vestibular nerve that innervates the ampulla of the lateral semicircular duct, ending around the hair cells of the ampullary crest.
• nervus ampullaris posterior / posterior ampullar nerve : the branch of the vestibular nerve that innervates the ampulla of the posterior semicircular duct, ending around the hair cells of the ampullary crest.
• nervus utriculoampullaris / utriculoampullary nerve : a nerve that arises by peripheral division of the vestibular nerve, and supplies the utricle and ampullae of the semicircular ducts.
• nervus utricularis / utricular nerve : the branch of the vestibular nerve that innervates the macula of the utricle
• glossopharyngeal nerve / nervus glossopharyngeus (IX)
• origin : nucleus nervi glossopharyngei; several rootlets from lateral side of upper part of medulla oblongata, between the olive and the inferior cerebellar peduncle
• branches :
• nervus tympanicus / Jacobson's tympanic nerve : origin, inferior ganglion of glossopharyngeal nerve; branches, helps form tympanic plexus; distribution, mucous membrane of tympanic cavity, mastoid air cells, auditory tube, and, via lesser petrosal nerve and otic ganglion, the parotid gland; modality, general sensory and parasympathetic.
• pharyngeal ramus
• stylopharyngeal ramus
• tonsillar ramus
• lingual ramus
• ramus to the carotid sinus
• ramus communicating with the auricular ramus of the vagus nerve
• distribution : it has 2 enlargements
• ganglion rostralis or superius nervi glossopharyngei / jugular, rostral or superior ganglion of glossopharyngeal nerve / Ehrenritter's ganglion : the upper of 2 ganglia on the glossopharyngeal nerve as it passes through the jugular foramen; it contains cell bodies for some of the afferent fibers of the nerve
• ganglion caudalis or inferius nervi glossopharyngei / caudal or inferior ganglion of glossopharyngeal nerve / inferior petrosal or petrous ganglion : the lower of 2 ganglia on the glossopharyngeal nerve as it passes through the jugular foramen; it contains cell bodies for some of the afferent fibers of the nerve
... and supplies the tongue, pharynx, and parotid gland
• intumescentia tympanica / tympanic enlargement / ganglion tympanicum / tympanic ganglion of Valentin / Valentin's pseudoganglion : a pseudoganglion on the tympanic branch (nerve) of the glossopharyngeal nerve
• modality : motor, parasympathetic, and general, special, and visceral sensory.
• cardiopneumogastric or vagus nerve / nervus vagus (X)
• origin : nuclei of vagus nerve; by numerous rootlets from lateral side of medulla oblongata in the groove between the olive and the inferior cerebellar peduncle
• branches :
• nervus laryngealis or laryngeus recurrens / recurrent laryngeal nerve : branches :
• nervus laryngealis or laryngeus inferior / inferior laryngeal nerve : origin, recurrent laryngeal nerve, especially the terminal portion of this nerve; distribution, intrinsic muscles of larynx, except cricothyroid; communicates with the internal laryngeal nerve; modality, motor
• tracheal ramus
• esophageal ramus
• inferior cardiac ramus
...; modality, parasympathetic, visceral afferent, and motor
• nervus laryngealis or laryngeus superior / superior laryngeal nerve : origin, inferior ganglion of vagus nerve; branches, external, internal, and communicating rami; distribution, inferior constrictor of the pharynx, cricothyroid muscle, and mucous membrane of back of tongue and larynx—see individual branches, under ramus; modality, motor, general sensory, visceral afferent, and parasympathetic
• meningeal ramus
• auricular ramus
• pharyngeal ramus
• cardiac ramus
• bronchial ramus
• gastric ramus
• hepatic ramus
• celiac ramus
• renal ramus
• pharyngeal plexus
• pulmonary plexus
• esophageal plexus
• truncus vagalis anterior / anterior vagal trunk : a nerve trunk (or trunks) formed by fibers from both left and right vagus nerves, collected from the anterior part of the esophageal plexus; it descends through the esophageal opening of the diaphragm to supply branches to the anterior surface of the stomach.
• truncus vagalis posterior / posterior vagal trunk : a nerve trunk or trunks formed by fibers from both left and right vagus nerves, collected from the posterior part of the esophageal plexus; it descends through the esophageal opening of the diaphragm to supply branches to the posterior surface of the stomach.
• distribution : descending through the jugular foramen, it presents as:
• ganglion rostralis or superius nervi vagi / jugular, rostral or superior ganglion of vagus nerve : a small ganglion on the vagus nerve in the jugular foramen, giving off a meningeal and an auricular branch and containing cell bodies for some of the afferent fibers of the nerve
• ganglion caudalis or inferius nervi vagi / caudal or inferior ganglion of vagus nerve / nodose ganglion : a ganglion of the vagus nerve just below the jugular foramen, in front of the transverse processes of the first and second cervical vertebrae; it contains cell bodies for some of the afferent fibers of the nerve
..., and continues through the neck and thorax into the abdomen. It supplies sensory fibers to the ear, tongue, pharynx, and larynx, motor fibers to the pharynx, larynx, and esophagus, and parasympathetic and visceral afferent fibers to thoracic and abdominal viscera
• modality : parasympathetic, visceral afferent, motor, general sensory.
• accessory nerve / nervus accessorius (XI)
• origin : by cranial roots from
• the side of the medulla oblongata (nucleus nervi accessorii)
• radix cranialis nervi accessorii / cranial root of accessory nerves / pars vagalis nervi accessorii : any of the nerve roots originating from the nucleus ambiguus and emerging from the side of the medulla oblongata below the roots of the vagus nerve; they then unite with the spinal portion in the jugular foramen. Their constituent fibers then form the internal branch, which joins the vagus nerve and is distributed to the soft palate, constrictors of the pharynx, and the larynx
• spinal roots from the side of the spinal cord (nucleus spinalis nervi accessorii from the upper 3 or more cervical segments)
• radix spinalis nervi accessorii / spinal root of accessory nerve / pars spinalis nervi accessorii : any of the nerve roots originating from the gray matter of the spinal cord and emerging from the side of the cord as far down as a level between the C3 and C7 nerves; they then form a trunk that ascends in the vertebral canal, passes through the foramen magnum, and unites with the cranial portion in the jugular foramen. The constituent fibers then form the external branch, which supplies the sternocleidomastoid and trapezius muscles
The roots unite to form the truncus nervi accessorii / trunk of accessory nerve, which divides into an internal branch (cranial portion) and an external branch (spinal portion)
• distribution : the internal branch to the vagus and thereby to the palate, pharynx, larynx, and thoracic viscera; the external branch branches to the sternocleidomastoid and trapezius muscles
• modality : parasympathetic and motor
• hypoglossal nerve / nervus hypoglossus (XII)
• origin : nucleus nervi hypoglossi; several rootlets in the anterolateral sulcus between the olive and the pyramid of the medulla oblongata; it passes through the hypoglossal canal to the tongue
• branches : lingual rami
• distribution : geniohioid, thyrohioid, styloglossus, hypoglossus, and genioglossus muscles and intrinsic muscles of the tongue
• modality : motor
• spinal nerves / nervi spinales : the 31 pairs of nerves that arise from the spinal cord and pass out between the vertebrae


• 8 nervi cervicales / cervical nerves : the 8 pairs of nerves (C1–C8) that arise from the cervical segments of the spinal cord and, except for the last pair, leave the vertebral column above the correspondingly numbered vertebra. The ventral branches of the upper four, on either side, unite to form the cervical plexus, and those of the lower four, together with the ventral branch of the first thoracic nerve, form most of the brachial plexus.
• 12 nervi thoracici / thoracic nerves : the 12 pairs of spinal nerves (T1–T12) that arise from the thoracic segments of the spinal cord, each pair leaving the vertebral column below the correspondingly numbered vertebra. They innervate the body wall of the thorax and upper abdomen.
• 5 nervi lumbales or lumbares / lumbar nerves : the 5 pairs of nerves (L1–L5) that arise from the lumbar segments of the spinal cord, each pair leaving the vertebral column below the correspondingly numbered vertebra. The ventral branches of these nerves participate in the formation of the lumbosacral plexus
• 5 nervi sacrales / sacral nerves : the 5 pairs of nerves (S1–S5) that arise from the sacral segments of the spinal cord; the ventral branches of the first four pairs participate in the formation of the sacral plexus.
• 1 nervus coccygeus / coccygeal nerve : either of the 31^st pair of spinal nerves (Co), arising from the coccygeal segment of the spinal cord.
At the beginning :
• fila radicularia nervi spinalis / rootlets of spinal nerve / root filaments of spinal nerve : the threadlike filaments by which the anterior and posterior roots of each spinal nerve are attached to the spinal cord
• radicle / radicula / ramulus : any one of the smallest branches of a vessel or nerve
• radix anterior nervi spinalis / anterior root of spinal nerve / ventral or motor root of spinal nerve / radix ventralis nervi spinalis / radix motoria nervi spinalis : the motor division of each spinal nerve, attached centrally to the spinal cord and joining peripherally with the corresponding posterior (sensory) root to form the nerve before it emerges through the intervertebral foramen. It conveys motor fibers to skeletal muscle and contains preganglionic autonomic fibers at thoracolumbar and sacral levels
• radix posterior nervi spinalis / posterior root of spinal nerve / dorsal or sensory root of spinal nerves / radix dorsalis nervi spinalis / radix sensoria nervi spinalis : the sensory division of each spinal nerve, attached centrally to the spinal cord and joining peripherally with the anterior (motor) root to form the nerve before it emerges through the intervertebral foramen: each posterior root conveys sensory fibers to the spinal cord and bears a
• ganglion sensorium nervi spinalis / spinal ganglion / ganglion spinale / dorsal root ganglion (DRG) : the ganglion found on the posterior root of each spinal nerve, composed of the unipolar nerve cell bodies of the sensory neurons of the nerve
• aberrant ganglion : a small ganglion sometimes found on a dorsal cervical nerve root between the spinal ganglia and the spinal cord.
• ansae nervorum spinalium / loops of spinal nerves : loops of nerve fibers joining the ventral roots of the spinal nerves.
• truncus nervi spinalis / trunk of spinal nerve : the usually very short nerve trunk formed by the ventral and dorsal roots of a spinal nerve. It emits :
• recurrent meningeal branches
• white communicating branches (myelinated preganglionic orthosympathetic fibers) which synapse with ganglion cell / gangliocyte (a form of large nerve cell characteristic of ganglia) in ganglia of sympathetic trunk
... and receive gray communicating branches (unmyelinated postganglionic orthosympathetic fibers).
Hilton's law : all motor nerves also innervate the joint moved by the innervated muscle and the skin above it => no purely motor nerve exist !
Then each nerve divides into :
• dorsal or posterior branch : all of them are mixed nerves for paravertebral skin and muscles, excepted the suboccipital nerve which is purely motor. The greater occipital and third occipital nerves give branches for sensory innervation of meninges of posterior cranial fossa that follow the IX, X, and XII cranial nerves in the reverse direction.
• nervus suboccipitalis / suboccipital nerve : origin, dorsal ramus of first cervical nerve; distribution, emerges above posterior arch of atlas and supplies muscles of suboccipital triangle and semispinalis capitis muscle; modality, motor.
• nervus occipitalis major / greater occipital nerve : origin, medial branch of dorsal ramus of C2; distribution, semispinalis capitis muscle and skin of scalp as far forward as the vertex; modality, general sensory and motor.
• nervus occipitalis tertius / third occipital nerve : origin, medial branch of dorsal ramus of C3; distribution, skin of upper part of back of neck and head; modality, general sensory.
• ventral or anterior branch, which from C1 to T1 and from T12 to Co1 intermingle with anterior bracnh of 1 or more other spinal nerve(s) to form plexus nervorum spinalium / plexus of spinal nerves. From T1 to T12 no plexuses are formed as cutaneous and muscular metamery is conserved during ontogenesis.
• plexus cervicalis / cervical plexus (C1-C4) : arranged as an irregular series of loops, it gives off
• superficial branches
• nervus occipitalis minor / lesser occipital nerve : origin, superficial cervical plexus—C2–C3; distribution, ascends behind the auricle and supplies some of the skin on the side of the head and on the cranial surface of the auricle; modality, general sensory.
• nervus auricularis magnus / great auricular nerve : origin, cervical plexus—C2–C3; branches, anterior and posterior rami; distribution, skin over parotid gland and mastoid process, and both surfaces of auricle; see individual branches under ramus; modality, general sensory.
• nervus transversus colli / transverse cervical nerve / cutaneous or transverse nerve of neck / nervus transversus cervicalis : origin, cervical plexus—C2–C3; branches, superior and inferior rami; distribution, skin on side and front of neck; modality, general sensory
• nervi supraclaviculares / supraclavicular nerves : a term denoting collectively the common trunk, which is a branch of the cervical plexus (C3–C4) and which emerges under cover of the posterior border of the sternocleidomastoid muscle and divides into
• nervi supraclaviculares intermedii / intermediate supraclavicular nerves : origin, cervical plexus—C3–C4; distribution, descend in the posterior triangle, cross the clavicle, and supply the skin over pectoral and deltoid region; modality, general sensory.
• nervi supraclaviculares laterales or posteriores / lateral supraclavicular nerves : origin, cervical plexus—C3–C4; distribution, descend in the posterior triangle, cross the clavicle, and supply the skin of superior and posterior parts of shoulder; modality, general sensory
• nervi supraclaviculares mediales / medial supraclavicular nerves : origin, cervical plexus—C3–C4; distribution, descend in posterior triangle, cross the clavicle, and supply the skin of medial infraclavicular region; modality, general sensory.
• deep branches
• nervus phrenicus / phrenic nerve : origin, cervical plexus—C4–C5; branches, pericardiac and phrenicoabdominal rami; distribution, pleura, pericardium, diaphragm, peritoneum, and sympathetic plexuses; modality, general sensory and motor.
• nervi phrenici accessorii / accessory phrenic nerves : an inconstant contribution of the fifth cervical nerve to the phrenic nerve; when present, they run a separate course to the root of the neck or into the thorax before joining the phrenic nerve.
• ansa cervicalis / ansa hypoglossi / loop of hypoglossal nerve : a nerve loop in the neck that supplies the infrahyoid muscles and that presents an anterior (superior) root, which connects with the hypoglossal nerve (and actually consists of fibers of the second or first cervical nerve), and an inferior root (nervus descendens cervicalis), which connects with the second and third cervical nerves
• radix anterior or superior ansae cervicalis / anterior or superior root of ansa cervicalis : fibers of the first or second cervical nerve, descending in company with the hypoglossal nerve, connecting it with the ansa cervicalis and helping supply the infrahyoid muscles
• radix inferior or posterior ansae cervicalis / inferior or posterior root of ansa cervicalis : a strand of filaments connecting the ansa cervicalis with branches of the second and third cervical nerves
• muscular nerves
• plexus brachialis / brachial plexus (C5-T1) : situated partly in the neck and partly in the axilla, it is composed successively of
• radices plexus brachialis / roots of brachial plexus : the anterior branches of the four lower cervical spinal nerves and the first thoracic nerve, which combine to form the trunks of the brachial plexus
• rami ventrales nervorum cervicalium
• rami ventrales nervorum thoracicorum
• trunci plexus brachialis / trunks of brachial plexus : the 3 trunks (superior, middle, and inferior) of the brachial plexus, arising from the anterior branches of the lower four cervical nerves and the first thoracic nerve near the lateral border of the scalenus anterior muscle; they continue laterally and downward, above and behind the subclavian artery, and near the clavicle each splits into an anterior and a posterior division. The anterior divisions of the superior and medial trunks unite to form the lateral fasciculus and that of the inferior trunk forms the medial fasciculus of the plexus; and the posterior divisions of the three trunks form the posterior fasciculus of the plexus.
• truncus superior plexus brachialis / superior trunk of brachial plexus / upper trunk of brachial plexus : the trunk of the brachial plexus that is formed by the anterior branches of the fifth and sixth cervical nerves. Its anterior division helps form the lateral cord of the plexus, its posterior division helps form the posterior cord, and it gives rise directly to the suprascapular and subclavian nerves; modality, general sensory and motor
• fasciculus medialis plexus brachialis / medial cord of brachial plexus : the medial bundle of fibers of the brachial plexus, formed by the anterior division of the inferior trunk, C8 through T1, and from which arise the medial pectoral, medial brachial cutaneous, and medial antebrachial cutaneous nerves, and the medial root of the ulnar and the median nerves.
• posterior fasciculus of brachial plexus / fasciculus posterior plexus brachialis / posterior cord of brachial plexus : the posterior bundle of fibers of the brachial plexus, formed by the union of the posterior divisions of the superior, middle, and inferior trunks, C5 through C8 and sometimes T1, and from which arise the subscapular, thoracodorsal, radial, and axillary nerves.
• truncus medius plexus brachialis / middle trunk of brachial plexus : the trunk of the brachial plexus that is formed by the anterior branch of the seventh cervical nerve. Its anterior division, from which lateral pectoral nerves may arise, helps form the lateral cord of the plexus, and its posterior division helps form the posterior cord; modality, general sensory and motor.
• lateral cord or fasciculus of brachial plexus / fasciculus lateralis plexus brachialis : the lateral bundle of fibers of the brachial plexus, formed by the union of the anterior divisions of the superior and middle trunks, C5 through C7, and from which arise the lateral pectoral and musculocutaneous nerves and the lateral root of the median and the ulnar nerves.
• truncus inferior plexus brachialis / inferior or lower trunk of brachial plexus : the trunk of the brachial plexus that is formed by the anterior branches of the eighth cervical and first thoracic nerves; medial pectoral nerves may arise from it. Its anterior division becomes the medial cord of the plexus, and its posterior division helps form the posterior cord; modality, general sensory and motor
• ventral branches and trunks (supraclavicular part) which are related to the subclavian artery and which give off the
• nervus dorsalis scapulae / dorsal scapular nerve : origin, brachial plexus—ventral ramus of C5; distribution, rhomboid muscles and occasionally the levator scapulae muscle; modality, motor
• nervus thoracicus longus / long thoracic nerve / Bell external respiratory nerve : origin, brachial plexus—ventral rami of C5–C7; distribution, descends behind brachial plexus to serratus anterior muscle; modality, motor.
• nervus subclavius / subclavian nerve : origin, upper trunk of brachial plexus—C5; distribution, subclavius muscle and sternoclavicular joint; modality, motor and general sensory.
• nervi subscapulares / subscapular nerves : origin, posterior cord of brachial plexus—C5; distribution, usually 2 or more nerves, upper and lower, supplying subscapularis and teres major muscles; modality, motor
• infraclavicular part consists of divisions which lie approximately behind the clavicle and cords and branches in the axilla in relation to the axillary artery. Its branches are
• nervus pectoralis lateralis / lateral pectoral nerve : origin, lateral cord of brachial plexus or anterior divisions of upper and middle trunks (C5–C7); distribution, usually several nerves supplying the musculus pectoralis minor and acromioclavicular and shoulder joints; modality, motor and general sensory.
• nervus pectoralis medialis / medial pectoral nerve : origin, medial cord or lower trunk of brachial plexus (C8, T1); distribution, usually several nerves supplying the musculus pectoralis major and musculus pectoralis minor; modality, motor.
• nervus cutaneus brachii medialis / medial cutaneous nerve of arm / medial brachial cutaneous nerve : origin, medial cord of brachial plexus (T1); distribution, skin on medial and posterior aspects of arm; modality, general sensory
• nervus cutaneus antebrachii medialis / medial cutaneous nerve of forearm / medial antebrachial cutaneous nerve : origin, medial cord of brachial plexus (C8, T1); branches, anterior and ulnar; distribution, skin of front, medial, and posteromedial aspects of forearm; modality, general sensory
• nervi subscapulares / subscapular nerves : origin, posterior cord of brachial plexus—C5; distribution, usually 2 or more nerves, upper and lower, supplying subscapularis and teres major muscles; modality, motor
• nervus thoracodorsalis / thoracodorsal nerve : origin, posterior cord of brachial plexus—C7–C8; distribution, latissimus dorsi muscle; modality, motor.
• nervus axillaris / axillary nerve
• origin, posterior cord of brachial plexus (C5–C6)
• branches
• nervus cutaneus brachii lateralis superior / superior lateral cutaneous nerve of arm / superior lateral brachial cutaneous nerve : origin, axillary nerve; distribution, skin of back of arm; modality, general sensory
• muscular rami
• distribution, deltoid and teres minor muscles, skin on back of arm
• modality, motor and general sensory
• nervus musculocutaneus / musculocutaneous nerve
• origin, lateral cord of brachial plexus—C5–C7
• branches :
• nervus cutaneus antebrachii lateralis / lateral cutaneous nerve of forearm / lateral antebrachial cutaneous nerve : origin, continuation of musculocutaneous nerve; distribution, skin over radial side of forearm and sometimes an area of skin of dorsum of hand; modality, general sensory
• muscular rami
• distribution, coracobrachialis, biceps brachialis muscles, the elbow joint, and skin of radial side of forearm
• modality, general sensory and motor
• nervus radialis / radial nerve
• origin, posterior cord of brachial plexus—C6–C8, and sometimes C5 and T1
• branches
• nervus cutaneus brachii posterior / posterior cutaneous nerve of arm / posterior brachial cutaneous nerve : origin, radial nerve in the axilla; distribution, skin on back of arm; modality, general sensory
• nervus cutaneus brachii lateralis inferior / inferior lateral cutaneous nerve of arm / inferior lateral brachial cutaneous nerve : origin, radial nerve; distribution, skin of lateral surface of lower part of arm; modality, general sensory
• nervus cutaneus antebrachii posterior / posterior cutaneous nerve of forearm / posterior antebrachial cutaneous nerve : origin, radial nerve; distribution, skin of dorsal aspect of forearm; modality, general sensory
• muscular ramus
• deep ramus
• superficial ramus
• distribution, descending in the back of arm and forearm, it is ultimately distributed to skin on back of arm, forearm, and hand, extensor muscles on back of arm and forearm, and elbow joint and many joints of hand
• modality, general sensory and motor.
• nervus medianus / median nerve :
• origin, lateral and medial cords of brachial plexus—C6–T1
• radix medialis nervi mediani / medial root of median nerve : the fibers contributed to the median nerve by the medial cord of the brachial plexus.
• radix lateralis nervi mediani / lateral root of median nerve : the fibers contributed to the median nerve by the lateral cord of the brachial plexus.
• branches, anterior interosseous nerve of forearm, common palmar digital nerves, and muscular and palmar rami, and a communicating branch with the ulnar nerve
• distribution, ultimately, skin on front of lateral part of hand, most of flexor muscles of front of forearm, most of short muscles of thumb and elbow joint, and many joints of hand
• modality, general sensory
• nervus ulnaris / ulnar nerve
• origin, medial and lateral cords of brachial plexus—C7–T1
• branches, muscular, dorsal, palmar, superficial, and deep rami
• distribution, ultimately to skin on front and back of medial part of hand, some flexor muscles on front of forearm, many short muscles of hand, elbow joint, many joints of hand
• modality, general sensory and motor
• 11 pairs of nervi intercostales / intercostal nerves / anterior or ventral branches of thoracic nerves / rami anteriores or ventrales nervorum thoracicum: branches of the first eleven thoracic spinal nerves, situated between the ribs. The first three send branches to the brachial plexus as well as to the thoracic wall; the fourth, fifth, and sixth supply only the thoracic wall; and the seventh through eleventh are thoracoabdominal in distribution. The primary anterior division of the twelfth thoracic nerve is subcostal rather than intercostal in position and is known as the nervus subcostalis / subcostal nerve (origin, anterior ramus of twelfth thoracic nerve; distribution, skin of lower abdomen and lateral side of gluteal region, parts of transversus, oblique, and rectus muscles, and usually the pyramidalis muscle, and adjacent peritoneum; modality, general sensory and motor). It differs in course and relationship from the other anterior branches and so is classified separately
• plexus lumbosacralis / lumbosacral plexus : a term applied to the lumbar and sacral nerve plexuses together, because of their continuous nature
• plexus lumbalis / lumbar plexus (L2-L5) : in the psoas major muscle (the branches of the L1 nerve often are included)
• the lower division of the L4 nerve joins L5, and the lumbosacral trunk thus formed becomes part of the sacral plexus
• the branches of the first lumbar nerve are
• nervus ilioinguinalis / ilioinguinal nerve : origin, lumbar plexus—L1 (sometimes T12); accompanies the spermatic cord through the inguinal canal; branches, anterior scrotal or labial rami; distribution, skin of scrotum or labia majora, and adjacent part of thigh; modality, general sensory
• nervus iliohypogastricus / iliohypogastric nerve / nervus iliopubicus / iliopubic nerve : origin, lumbar plexus—L1 (sometimes T12); branches, lateral and anterior cutaneous rami; distribution, the skin above the pubis and over the lateral side of the buttock, and occasionally the pyramidalis; modality, motor and general sensory
• branches of the plexus proper are :
• femoral nerve / nervus femoralis
• origin, lumbar plexus—L2–L4; descending behind the inguinal ligament to the femoral triangle
• branches
• nervus saphenus / saphenous nerve : origin, termination of femoral nerve, descending first with femoral vessels and then on medial side of leg and foot; branches, infrapatellar and medial crural cutaneous rami; distribution, knee joint, subsartorial and patellar plexuses, skin on medial side of leg and foot—see individual branches, under ramus; modality, general sensory.
• muscular and anterior cutaneous rami
• distribution, the skin of the thigh and leg, the muscles of the front of the thigh, and the hip and knee joints
• modality, general sensory and motor.
• nervus genitofemoralis / genitofemoral nerve : origin, lumbar plexus—L1–L2; branches, genital and femoral rami; modality, general sensory and motor.
• nervus cutaneus femoris lateralis / lateral femoral cutaneous nerve / lateral cutaneous nerve of thigh
• origin, lumbar plexus—L2–L3
• distribution, skin of lateral and frontal aspects of thigh
• modality, general sensory
• obturator nerve / nervus obturatorius : origin, lumbar plexus—L3–L4
• branches : anterior, posterior, and muscular rami
• distribution, adductor muscles and gracilis muscle, skin of medial part of thigh, and hip and knee joints
• modality, general sensory and motor.
• plexus sacralis / sacral plexus (L4-S3)
• truncus lumbosacralis / lumbosacral trunk (L4-L5) descends to the sacral plexus.
It has 12 named branches :
• 5 supplying pelvic structures
• nervus musculi piriformis / nerve to piriformis / nervus piriformis / piriform nerve : origin, dorsal branches of ventral rami of S1–S2; distribution, anterior piriform muscle; modality, general sensory and motor
• pelvic splanchnic nerves / nervi splanchnici pelvici / radix parasympathica gangliorum pelvicorum
• pudendal plexus / plexus pudendalis (S2-S4) :
• nervus pudendus / pudendal nerve : origin, sacral plexus— S2–S4; branches, enters the pudendal canal, gives off the inferior rectal nerve, and then divides into the perineal nerve and dorsal nerve of the penis (clitoris); distribution, muscles, skin, and erectile tissue of perineum—see individual branches; modality, general sensory, motor, and parasympathetic.
• nervi perineales / perineal nerves : origin, pudendal nerve in the pudendal canal; branches, muscular branches and posterior scrotal or labial nerves; distribution, muscular branches supply the bulbospongiosus, ischiocavernosus, superficial transversus perinei muscles and bulb of the penis and, in part, the sphincter ani externus and levator ani; the scrotal (labial) nerves supply the scrotum or labium majus; modality, general sensory and motor.
• 7 helping supply the buttocks and lower limbs :
• nervus gluteus inferior / inferior gluteal nerve : origin, sacral plexus—L5–S2; distribution, gluteus maximus muscle; modality, motor.
• nervus gluteus superior / superior gluteal nerve : origin, sacral plexus—L4–S1; distribution, gluteus medius and minimus muscles, tensor fasciae latae, and hip joint; modality, motor and general sensory.
• nervus cutaneus femoris posterior / posterior femoral cutaneous nerve / posterior cutaneous nerve of thigh : origin, sacral plexus—S1–S3; branches, rami clunium inferiores and perineal rami; distribution, skin of buttock, external genitalia, and back of thigh and calf; modality, general sensory
• nervus cutaneus perforans / perforating cutaneous nerve : one of the inferior clunial nerves which pierces the sacrotuberous ligament and supplies the skin over the inferomedial gluteus maximus; it is absent in one third of the population.
• nervus musculi quadrati femoris / nerve to quadratus femoris / nervus quadratus femoris : origin, ventral branches of ventral rami of L4–L5; distribution, gemellus inferior, anterior quadratus femoris muscle, hip joint; modality, general sensory and motor
• nervus musculi obturatorii interni / nerve to obturator internus / nervus obturatorius internus / obturator nerve : origin, ventral branches of ventral rami of L5, S1–S2; distribution, posterior gemellus superior muscle and obturator internus muscle; modality, general sensory and motor
• sciatic nerve / nervus sciaticus / nervus ischiaticus : the largest nerve of the body:
• origin, sacral plexus—L4–S3; it leaves the pelvis through the greater sciatic foramen
• branches : in lower third of thigh it divides into ...
• nervus tibialis / tibial nerve / internal or medial popliteal nerve :
• branches
• nervus interosseus cruris / interosseous nerve of leg / crural interosseous nerve :
• distribution, interosseous membrane and tibiofibular syndesmosis
• modality, general sensory
• nervus cutaneus surae medialis / medial sural cutaneous nerve / medial cutaneous nerve of calf : usually joins peroneal communicating branch of common peroneal nerve to form the sural nerve
• distribution, may continue as the sural nerve
• modality, general sensory
• nervus suralis / sural nerve
• origin, medial sural cutaneous nerve and peroneal communicating branch of common peroneal nerve
• branches, lateral dorsal cutaneous nerve and lateral calcaneal rami; distribution, skin on back of leg, and skin and joints on lateral side of heel and foot
• modality, general sensory
• nervus plantaris lateralis / lateral plantar nerve
• origin, the smaller of terminal branches of tibial nerve
• branches, muscular, superficial, and deep rami
• distribution, lying between first and second layers of muscles of sole, it supplies the quadratus plantae, abductor digiti minimi, flexor digiti minimi brevis, adductor hallucis, interossei, and second, third, and fourth lumbrical muscles, and gives off cutaneous and articular twigs to lateral side of sole and fourth and fifth toes
• modality, general sensory and motor
• nervus plantaris medialis / medial plantar nerve :
• origin, the larger of the terminal branches of tibial nerve
• branches, common plantar digital nerves and muscular rami
• distribution, abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and first lumbrical muscles, and cutaneous and articular twigs to the medial side of the sole, and to the first to fourth toes
• modality, general sensory and motor.
• muscular and medial calcaneal rami
• distribution, while still incorporated in the sciatic nerve, it supplies the semimembranosus and semitendinosus muscles, long head of biceps, and adductor magnus muscle; it supplies the knee joint as it descends in the popliteal fossa and, continuing into the leg, supplies the muscles and skin of the calf and sole of the foot, and the toes
• common fibular or peroneal nerve / nervus fibularis or peroneus communis / external or lateral popliteal nerve
• branches and distribution, supplies
• short head of biceps femoris muscle (while still incorporated in sciatic nerve)
• gives off lateral sural cutaneous nerve and fibular communicating branch as it descends in popliteal fossa, supplies knee and superior tibiofibular joints and tibialis anterior muscle, and divides into superficial and deep fibular nerves
• modality, general sensory and motor
• plexus coccygeus / coccygeal plexus (S4-Co3)
• nervus anococcygeus / anococcygeal nerve : origin, coccygeal plexus; distribution, sacrococcygeal joint, coccyx, skin over the coccyx; modality, general sensory.
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• autonomic nervous system (ANS)


• neurons
• adrenergic neurons
• cholinergic neurons
• peptidergic neurons
• preganglionic neurons : neurons in the ANS whose cell bodies lie in the CNS and whose efferent fibers terminate in the autonomic ganglia
• ganglion autonomicum / autonomic ganglion / visceral ganglion / ganglion viscerale : the ganglia found
• along the truncus sympatheticus / truncus sympathicus / sympathetic trunk : 2 long nerve strands, one on each side of the vertebral column, extending from the base of the skull to the coccyx. Interconnected by nerve strands, each has cervical, thoracic, lumbar, and sacral sympathetic ganglia. These receive preganglionic fibers from thoracic and upper lumbar anterior roots by way of rami communicantes, send postganglionic fibers to anterior roots by rami communicantes, and give branches to prevertebral plexuses and adjacent viscera and blood vessels.
• on the peripheral plexuses
• within the walls of organs supplied by the autonomic nervous system
They are divided into 2 structurally similar groups, the sympathetic ganglia and the parasympathetic ganglia
• ganglion parasympathicum / parasympathetic ganglion : one of the aggregations of cell bodies of primarily cholinergic neurons of the parasympathetic nervous system, located near to or within the wall of the organs being innervated
• ganglion sympatheticum or sympathicum / sympathetic ganglion : any of the aggregations of cell bodies of primarily adrenergic neurons of the sympathetic nervous system, including the
• ganglia intermedia / intermediate or accessory ganglia : small groups of sympathetic nerve cells present on spinal nerves and on rami communicantes, especially in the cervical, lower thoracic, and upper lumbar regions
• prevertebral ganglia : sympathetic ganglia (other than those of the sympathetic trunk) in the prevertebral plexuses of the thorax and abdomen.
• some ganglionic cells in the autonomic plexuses.
• ganglia trunci sympathetici or sympathici / ganglia of sympathetic trunk : sympathetic ganglia that are arranged in a chainlike fashion along each sympathetic trunk, about twenty to twenty-three on either side
• ganglion cervicale superius / superior cervical ganglion : the uppermost ganglion on the sympathetic trunk, lying behind the internal carotid artery and in front of the second and third cervical vertebrae; it gives rise to postganglionic fibers to the heart via cervical cardiac nerves, to the pharyngeal plexus and thence to the larynx and pharynx, and to the head via the external and internal carotid plexuses.
• ganglion cervicale medium / middle cervical ganglion : a variable ganglion, often fused with the vertebral ganglion, on the sympathetic trunk at about the level of the cricoid cartilage; its postganglionic fibers are distributed mainly to the heart, cervical region, and upper limb.
• ansa subclavia / subclavian loop / ansa of Vieussens / annulus of Vieussens : nerve filaments that pass anterior and posterior to the subclavian artery to form a loop interconnecting the middle and inferior cervical ganglia
• ganglion cervicale inferioris / inferior cervical ganglion : an inconstant ganglion formed in place of the usual cervicothoracic ganglion by fusion of the lower two cervical ganglia in instances where the first thoracic ganglion remains separate.
• ganglion cervicothoracicum / cervicothoracic ganglion / stellate ganglion / ganglion stellatum : a ganglion on the sympathetic trunk at the level of the 7th cervical and 1st thoracic vertebrae, anterior to the 8th cervical and 1st thoracic nerves; it has two components, the inferior cervical and first thoracic ganglia, which are usually fused, partially or completely. Its postganglionic fibers are distributed to the head and neck, heart, and upper limb
• ganglia thoracica / thoracic ganglia : the ganglia on the thoracic portion of the sympathetic trunk, about eleven or twelve on either side.
• ganglion thoracicum splanchnicum / splanchnic thoracic ganglion / ganglion splanchnicum and splanchnic ganglion : a small ganglion formed on the greater thoracic splanchnic nerve near the twelfth thoracic vertebra
• postganglionic neurons : neurons in the ANS whose cell bodies are situated in the autonomic ganglia and whose purpose is to relay impulses beyond the ganglia
• portions
• pars thoracica autonomica / thoracic autonomic part / pars thoracica systematis autonomici : the portion of the autonomic nervous system contained within the thorax; its sympathetic components are derived from the upper thoracic spinal cord and its parasympathetic components from the vagus nerves. It also contains preganglionic sympathetic fibers that reach abdominal viscera by way of thoracic splanchnic nerves
• pars abdominalis autonomica / abdominal autonomic part / abdominal or lumbar part of autonomic nervous system / pars abdominalis systematis autonomici : the portion of the autonomic nervous system contained within the abdomen; part of its parasympathetic components (the vagus nerves) arise from the medulla oblongata and the sacral spinal cord, and its sympathetic components arise from the thoracic and upper lumbar cord
• pars sympathica divisionis autonomici systematis nervosi / sympathetic nervous system / thoracolumbar division and thoracolumbar part of autonomic nervous system : the portion of the autonomic nervous system that receives its fibers of connection with the CNS through the thoracolumbar outflow of visceral efferent fibers. These fibers (preganglionic) arise from cells in the thoracic and upper lumbar levels of the spinal cord, leave by way of ventral roots, and, by way of rami communicantes, enter sympathetic trunks, where some synapse with ganglion cells. The fibers (postganglionic) of these ganglion cells return to spinal nerves by way of rami communicantes to supply the blood vessels, smooth muscle, and glands of the trunk and limbs, or go as visceral branches to the blood vessels, smooth muscles, and glands of the head and neck, and the viscera of the thorax, abdomen, and pelvis. Some preganglionic fibers pass through the sympathetic trunks and synapse in the prevertebral ganglia; postganglionic fibers from those ganglia supply adjacent viscera
• Cannon-Bard emergency theory : the theory that the adrenal medulla is stimulated during emotional excitement, pain, and bodily emergencies
• alarm reaction / fight-or-flight reaction : the physiologic effects in response to acute stress, fright, or rage (increased blood pressure and cardiac output, increased blood flow to skeletal muscles, decreased flow to the viscera, increased rate of glycolysis and blood glucose concentration), mediated by sympathetic nervous system discharge and release of adrenal medullary hormones
• stress reaction : any of the biological reactions to adverse stimuli, physical, mental, or emotional, internal or external, that tend to disturb the organism's homeostasis; should these compensating reactions, physiological or psychological, be inadequate or inappropriate, they may lead to disorders (general adaptation syndrome, acute stress disorder, adjustment disorder, and posttraumatic stress disorder)
• relaxation response : a group of physiologic changes that cause decreased activity of the sympathetic nervous system and consequent relaxation after stimulation of certain regions of the hypothalamus. They are the opposite of the alarm reaction and may be self-induced through techniques such as meditation and biofeedback.
• pars parasympathica divisionis autonomici systematis nervosi / parasympathetic nervous system / craniosacral division and craniosacral part of autonomic nervous system : the craniosacral division of the autonomic nervous system, its preganglionic fibers traveling with cranial nerves III, VII, IX, X, and XI, and with the second to fourth sacral ventral roots; it innervates the heart, the smooth muscle and glands of the head and neck, and the thoracic, abdominal, and pelvic viscera. The ganglion cells with which these fibers synapse are in or near the organs innervated
• pars cranialis partis parasympathici divisionis autonomici systematis nervosi / cranial part of parasympathetic part of autonomic division of nervous system : the part of the parasympathetic nervous system that includes cranial nerves III, VII, IX, and X and the ciliary, pterygopalatine, otic, and submandibular ganglia.
• ganglion ciliare / ciliary ganglion : a parasympathetic ganglion in the posterior part of the orbit; it receives preganglionic fibers from the oculomotor nerve, and its postganglionic fibers supply the ciliary muscle and the sphincter pupillae. Sensory and postganglionic sympathetic fibers pass through the ganglion.
• nervi ciliares breves / short ciliary nerves : origin, ciliary ganglion; distribution, smooth muscle and tunics of eye; modality, parasympathetic, sympathetic, and general sensory.
• radix oculomotoria or parasympathica ganglii ciliaris / parasympathetic root of ciliary ganglion / ramus nervi oculomotorii ad ganglion ciliare / motor, short, or oculomotor root of ciliary ganglion : a short collection of fibers passing from the inferior branch of the oculomotor nerve to the posterior inferior portion of the ciliary ganglion; it contains preganglionic parasympathetic fibers for the sphincter papillae and the ciliary muscle
• radix sensoria ganglii ciliaris / sensory root of ciliary ganglion / radix nasociliaris ganglii ciliaris / ramus communicans nervi nasociliaris cum ganglio ciliari / long or nasociliary root of ciliary ganglion : sensory fibers from the cornea, iris, ciliary body, and choroid that pass through the ciliary ganglion to the nasociliary nerve
• radix sympathetica ganglii ciliaris / radix sympathica ganglii ciliaris / sympathetic root of ciliary ganglion / ramus sympatheticus ganglii ciliaris / ramus sympathicus ganglii ciliaris : postganglionic fibers from the superior cervical ganglion, derived from the internal carotid plexus, to the ciliary ganglion, for distribution by the short ciliary nerves to the dilator muscle of the pupil, orbital muscle and tarsal muscles, and blood vessels of the eyeball
• ganglion pterygopalatinum / Meckel's pterygopalatine, sphenomaxillary or sphenopalatine ganglion : a parasympathetic ganglion in the pterygopalatine fossa; its preganglionic fibers are derived from the facial nerve via the greater petrosal nerve and the nerve of the pterygopalatine canal. Its postganglionic fibers supply the lacrimal, nasal, and palatine glands; sensory and sympathetic fibers pass through the ganglion
• radix sympathica ganglii pterygopalatini / nervus petrosus profundus. NOTE: when considering the ganglia of the pars parasympathica, this is the preferred term in the official nomenclature.
• radix parasympathica ganglii pterygopalatini / nervus petrosus major. NOTE: when considering the ganglia of the pars parasympathica, this is the preferred term in the official nomenclature.
• ganglion oticum / otic ganglion : a parasympathetic ganglion in the infratemporal fossa, medial to the mandibular nerve and just inferior to the foramen ovale: its preganglionic fibers are derived from the glossopharyngeal nerve via the lesser petrosal nerve, and its postganglionic fibers supply the parotid gland. Sensory and postganglionic sympathetic fibers pass through the ganglion.
• radix parasympathica ganglii otici / nervus petrosus minor. NOTE: when considering the ganglia of the pars parasympathica, this is the preferred term in the official nomenclature.
• ganglion sublinguale / sublingual ganglion : a ganglion of nerve cells sometimes found on the fibers passing distally from the submandibular ganglion to the lingual nerve.
• ganglion submandibulare / submandibular ganglion : a parasympathetic ganglion located superior to the deep part of the submandibular gland, on the lateral surface of the hyoglossus muscle; its preganglionic fibers are derived from the facial nerve by way of the chorda tympani and lingual nerve, and its postganglionic fibers supply the submandibular and sublingual glands; sensory and postganglionic sympathetic fibers pass through the ganglion.
• pars pelvica partis parasympatheticae systematis nervosi autonomici / pelvic part of parasympathetic part of autonomic division of nervous system : the part of the parasympathetic nervous system that includes the second to fourth anterior sacral roots and the sacral splanchnic nerves.
• prevertebral plexuses : autonomic nerve plexuses situated in the thorax, abdomen, and pelvis, anterior to the vertebral column; they consist of visceral afferent fibers, preganglionic parasympathetic fibers, preganglionic and postganglionic sympathetic fibers, and ganglia containing sympathetic ganglion cells, and they give rise to postganglionic fibers. All are closely related to the aorta; those in the abdomen and pelvis supply adjacent viscera by subdivisions which accompany the branches of the aorta and which are named usually after these branches, but sometimes according to the organ supplied. The major plexuses are
• cardiac
• plexus pulmonalis : a nerve plexus formed by several strong trunks of the vagus nerve that are joined at the root of the lung by branches from the sympathetic trunk and cardiac plexus. The plexus is often described as having anterior and posterior parts; filaments from each accompany the blood vessels and bronchi into the lungs.
• anterior pulmonary plexus : the smaller portion of the pulmonary plexus, located in front of the root of the lung and interconnected with the posterior pulmonary plexus.
• posterior pulmonary plexus : the larger portion of the pulmonary plexus, located behind the root of the lung and interconnected with the anterior pulmonary plexus.
• plexus oesophagealis or oesophageus / esophageal plexus : a plexus surrounding the esophagus formed by branches of the left and right vagi and sympathetic trunks and containing also visceral afferent fibers from the esophagus; it is subdivided into anterior and posterior parts.
• plexus celiacus or coeliacus / celiac or solar plexus : a prevertebral plexus that lies on the front and sides of the aorta at the origins of the celiac trunk and superior mesenteric and renal arteries. It contains the paired celiac ganglia, the superior mesenteric ganglion (or ganglia), and small unnamed ganglionic masses. Branches of the plexus extend along all of the adjacent arteries
• plexus hepaticus / hepatic plexus : a subdivision of the celiac plexus accompanying the hepatic artery to the liver.
• plexus pancreaticus / pancreatic plexus : a subdivision of the celiac plexus, accompanying pancreatic arteries.
• plexus splenicus / splenic plexus : a subdivision of the celiac plexus, which accompanies the splenic artery
• plexus renalis / renal plexus : a subdivision of the celiac plexus, accompanying the renal artery.
• plexus suprarenalis / suprarenal plexus : a subdivision of the celiac plexus, in proximity with and supplying nerve fibers to an adrenal (suprarenal) gland.
• plexus gastrici / gastric plexuses : subdivisions of the celiac portion of the prevertebral plexuses, accompanying the gastric arteries and branches and supplying nerve fibers to the stomach
• inferior gastric plexus : the inferior portion of the gastric plexuses, located on the greater curvature of the stomach
• superior gastric plexus / left gastric plexus : the superior portion of the gastric plexuses, accompanying the left gastric artery on the lesser curvature of the stomach
• plexus mesentericus inferior / inferior mesenteric plexus : a subdivision of the aortic plexus accompanying the inferior mesenteric artery
• plexus mesentericus superior / superior mesenteric plexus : a subdivision of the celiac plexus accompanying the superior mesenteric artery
• plexus intermesentericus / intermesenteric plexus : the part of the aortic plexus that is located between the origins of the superior and inferior mesenteric arteries.
• plexus hypogastricus / hypogastric plexus : the hypogastric portion of the prevertebral plexuses
• plexus hypogastricus inferior / inferior hypogastric plexus / pelvic plexus / plexus pelvicus / plexus pelvina : the plexus formed on each side at the front of the lower part of the sacrum by the junction of the hypogastric and pelvic splanchnic nerves; branches are given off to the pelvic organs
• plexus prostaticus / prostatic plexus / Santorini's plexus : a subdivision of the inferior hypogastric plexus that supplies nerve fibers to the prostate and adjacent organs
• plexus uterovaginalis / uterovaginal plexus : the subdivision of the inferior hypogastric plexus that supplies nerve fibers to the uterus, ovary, vagina, urethra, and erectile tissue of the vestibule.
• plexus vesicalis / vesical plexus : the subdivision of the inferior hypogastric plexus that supplies sympathetic nerve fibers to the urinary bladder and parts of the ureter, ductus deferens, and seminal vesicle
• plexus hypogastricus superior / superior hypogastric plexus / nervus presacralis / presacral nerve : the downward continuation of the aortic plexus; it lies in front of the upper part of the sacrum, just below the bifurcation of the aorta, receives fibers from the lower lumbar splanchnic nerves, and divides into the right and left hypogastric nerves
• plexus periarterialis / periarterial plexus : a network of autonomic and sensory nerve fibers in the adventitia of an artery, some of which follow the course of the artery to reach and innervate other structures and some of which innervate the artery itself
• superficial temporal plexus : a plexus of nerve fibers accompanying the superficial temporal artery.
• inferior thyroid plexus : a nerve plexus accompanying the inferior thyroid artery to the larynx, pharynx, and thyroid region.
• superior thyroid plexus : a nerve plexus accompanying the superior thyroid artery to the larynx, pharynx, and thyroid region.
• tonsillar plexus : a plexus around the tonsil, formed by communications between the middle and posterior palatine nerves and the tonsillar branches of the glossopharyngeal nerve; fibers are supplied to the tonsil, soft palate, and region of the fauces.
• plexus subclavius / subclavian plexus : a sympathetic nerve plexus on the subclavian artery, arising from the cervicothoracic ganglion, contributing fibers to the phrenic nerve and to the branches of the subclavian artery, and continuing to the axillary artery
• plexus vertebralis / vertebral plexus : a nerve plexus accompanying the vertebral artery, formed by fibers from the vertebral and cervicothoracic ganglia and carrying sympathetic fibers to the posterior cranial fossa via cranial nerves.
• plexus pharyngeus nervi vagi / pharyngeal plexus of vagus nerve / plexus pharyngealis nervi vagi : a plexus formed chiefly by fibers from branches of the vagus nerves, but also containing fibers from the glossopharyngeal nerves and sympathetic trunks, and supplying motor, general sensory, and sympathetic innervation to the muscles and mucosa of the pharynx and soft palate, except for the tensor veli palatini muscle
• phrenic plexus : a nerve plexus accompanying the inferior phrenic artery to the diaphragm and suprarenal glands.
• plexus aorticus thoracalis / plexus aorticus thoracicus / thoracic aortic plexus : a plexus around the thoracic aorta formed by filaments from the sympathetic trunks and vagus nerves, and from which fine twigs accompany branches of the aorta. It is continuous below with the celiac plexus and the abdominal aortic plexus
• plexus aorticus abdominalis / abdominal aortic plexus : an unpaired plexus composed of interconnecting bundles of fibers that arise from the celiac and superior mesenteric plexuses and descend along the aorta. Receiving branches from the lumbar splanchnic nerves, it becomes the superior hypogastric plexus below the bifurcation of the aorta. Branches of the plexus are distributed along the adjacent branches of the aorta
• plexus testicularis / testicular plexus / spermatic plexus : a subdivision of the aortic plexus accompanying the testicular arteries
• plexus uretericus / ureteric plexus : a plexus supplying the ureter and derived from the renal and hypogastric plexuses.
• ileocolic plexus : the part of the superior mesenteric plexus that accompanies the ileocolic artery
• plexus iliacus / iliac plexus : any of the plexuses derived chiefly from the aortic plexus and accompanying the common iliac arteries.
• plexus iliacus externus : a lymphatic plexus situated about the external iliac vessels.
• plexus rectalis inferior / inferior rectal plexus : a plexus accompanying the inferior rectal artery, derived chiefly from the inferior rectal nerve.
• plexus rectalis medius / middle rectal plexus /  middle hemorrhoidal plexus : a subdivision of the inferior hypogastric plexus, in proximity with and supplying nerve fibers to the rectum
• plexus rectalis superior / superior rectal plexus / superior hemorrhoidal plexus : a plexus accompanying the superior rectal artery to the rectum, derived from the inferior mesenteric and hypogastric plexuses
• plexus femoralis / femoral plexus : a plexus accompanying the femoral artery, derived chiefly from the aortic plexus by way of the common and external iliac plexuses.
• plexus inguinalis / inguinal plexus : a lymphatic plexus situated near the end of the long saphenous vein and along the femoral artery and vein in the iliopectineal fossa.
• patellar plexus : a plexus of nerve fibers in front of the knee, formed by communications between branches of the saphenous nerves and the femoral cutaneous nerves.
• subsartorial plexus : a nerve plexus deep to the sartorius muscle, formed by communications between branches of the medial femoral cutaneous nerve and the saphenous and obturator nerves.
• subtrapezius plexus : a term sometimes applied to a small plexus situated deep to the trapezius muscle, formed by communications between branches of the accessory nerve and cervical nerves.
• intramural plexus : a plexus of autonomous intrinsic nerve cells and fibers which are confined entirely to the intestinal and bladder walls, and which take part in or regulate local reflexes and activity
• plexus entericus / enteric plexus : a plexus of autonomic nerve fibers within the wall of the digestive tube, and made up of the
• submucosal plexus / plexus submucosus / submucous plexus : the part of the enteric plexus that is situated in the submucosa
• Meissner's superficial submucosal plexus
• Henle's deep submucosal plexus
• plexus myentericus / Auerbach's myenteric plexus : that part of the enteric plexus within the tunica muscularis
• plexus subserosus / subserosal plexus : the part of the enteric plexus situated deep to the serosal surface of the tunica serosa
It contains :
• visceral afferent fibers
• sympathetic postganglionic fibers
• parasympathetic preganglionic and postganglionic fibers
• parasympathetic postganglionic cell bodies
• enteric glial cell
Normally neuroblasts are found in the wall of esophagus at week 6, in colon and rectum at week 12, and mature slowly in 5 years. Defects in migration or differentiation cause Hirschprung's disease
Functional consequences of normal ANS activation :

	sympathetic	parasympathetic
heart rate	increased	decreased
blood pressure	increased	mildly decreased
bladder	increased sphincter tone	voiding (decreased tone)
bowel motility	decreased motility	increased
lung	bronchodilation	bronchoconstriction
sweat glands	sweating	-
pupils	dilation	constriction
adrenal glands	catecholamine release	-
sexual function	ejaculation, orgasm	erection
lacrimal glands	-	tearing
parotid glands	-	salivation

• Web resources :
• Associations :
• Australian Neuroscience Society (ANS)
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• European Neuroscience Association (ENA)
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• Swiss Society for Neuroscience
• Women in Neuroscience
• Atlante anatomico del SNC at University of Bologna, Italy
• Atlas of Primate Brain
• Brain Connection
• Change Detection Database by Daniel Simons : change blindness and related attentional phenomena
• Department of Neurobiology at Weizmann Institute of Science, Rehovot, Israel
• Department of Neuroscience at Karolinska Institute, Stockholm, Sweden
• Dipartimento di Neuroscienze Bernard B.Brodie, University of Cagliari, Italy
• Dipartimento di Neuroscienze, University of Pisa, Italy
• Dipartimento di Neuroscienze, Mario Negri Institute, Milan, Italy
• Dipartimento di Neuroscienze, San Raffaele Institute, Milan, Italy
• Dipartimento di Scienze Neurologiche, University Federico II, Neaples, Italy
• eurosciences on the Internet - Neuroguide
• GEneral NEural SImulation System (GENESIS) by Caltech
• Global Brainstem
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• Journals :
• Molecular Psychiatry
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• Probe the brain
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• The secret life of the brain : 3-D brain anatomy
• The Whole Brain Atlas
• The WWW Virtual Library - Neurobiology
• Usenet bionet.neuroscience

• central, first or upper motoneurons travel from primary motor cortex (ascending frontal gyrus and pararolandic lobule : area 4) into the corticospinal tract via the knee and anterior 2/3 of posterior limb of capsula interna.
• bilateral innervation :
• motor nucleus of trigeminal (V) nerve
• upper nucleus of facial (VII) nerve
• nuclei of origin of  glossopharyngeal (IX) nerve (nucleus nervi glossopharyngei), vagus (X) nerve (nuclei of vagus nerve), accessory (XI) nerve (nucleus spinalis nervi accessorii and nucleus nervi accessorii), and hypoglossal (XII) nerve (nucleus nervi hypoglossi)
• homolateral innervation : all others
• contralateral innervation :
• lower nucleus of facial (VII) nerve
• those for trunk and limbs mostly cross at decussatio pyramidum and travel in the lateral cord of spinal cord (crossed pyramidal tract), while a few (direct pyramidal tract) cross in the spinal cord just before they synapse with ...
• peripheral, second or lower motor neuron
• nuclei of cranial nerves in the brainstem. The nuclei of extrinsic ocular muscles innervate agonist muscles on both eyes.
• anterior horn cells
... has trophic functions on innervated muscle fibers and is modulated by
• extracorticospinal or extrapyramidal system or tract : an imprecise term referring to a functional rather than an anatomical part of the central nervous system that controls motor activities and is not part of the pyramidal tract; it includes the corpus striatum, subthalamic nucleus, substantia nigra, and red nucleus along with their interconnections with the reticular formation, cerebrum, and cerebellum; they control and coordinate especially the postural, static, supporting, and locomotor mechanisms
• extrapyramidal fibers : from area 6 and 8 and basal ganglia to mesencephalic centers (mesodiencephalic center, nucleus ruber, and substantia nigra) and rhombencephalic centers (reticular formation). The extrapyramidal system regulates muscular tone, body attitude and instinctive motor automatism.

• uncoordinated and afinalistic (e.g. seizure, fibrillation)
• coordinated in space and time and finalistic => movement (kinesiology). According to Kuypers ....
• mediated by medial systems (in spinal cord found in anterior columns and ventral part of lateral columns) => axial and proximal bilateral muscles with large motor units
• physiological reflexes :
• to annihilate stimuli
• perceptive stimuli (e.g. accommodation reflex, light or pupillary reflex, vergence reflex)
• defensive reflexes (e.g. direct and indirect myotatic reflex, scraping reflex, corneal reflex, light or pupillary reflex, plantar reflex, limb removal reflex)
• attitude reflexes
• static reflex : any of the reflexes for maintenance of position and righting of the body, such as the postural reflex, righting reflex, or vestibular reflexes.
• postural or antigravitary reflexes : a reflex which consists of some assumption of posture. The equilibrium is the ability to maintain an upright posture
• righting reflex : the ability to assume optimal position when there has been a departure from it.
• vestibular reflexes : the reflexes for maintaining the position of the eyes and body in relation to changes in orientation of the head; the neural pathways are complex, traveling from the vestibular nerve to the vestibular nuclei and thence to the involved muscles of the eye and body
• vestibulo-ocular reflex : nystagmus or deviation of the eyes in response to stimulation of the vestibular system by angular acceleration or deceleration or when the caloric test is performed (irrigation of the ears with warm or cool water or air)
• equilibration reflexes
• straighting reflexes
• taxis reflexes
They are unconditioned (genetically determined) or conditioned (supraaxial), rapid, stereotyped movements with high performance. They are expecially associated with spinal cord (spinal automatic reflexes) ... :
• crossed adductor reflex : adduction of one leg when an attempt is made to elicit the quadriceps jerk on the opposite side.
• crossed extension reflex : reflex extension of a leg or forearm in response to a noxious stimulation evoking a flexion reflex in the contralateral foot sole or hand
• nociceptive reflexes : reflexes initiated by painful stimuli
• withdrawal reflex : a nociceptive reflex in which a body part is quickly moved away from a painful stimulus.


• myotatic or stretch reflex / Liddell and Sherrington reflex : reflex contraction or irritability of a muscle (myotatic contraction) in response to sudden passive longitudinal stretching. Th basal reflex is the only monosynaptic reflex known. It is seen in extensor muscles of lower limbs and flexor (in bipeds) or extensor (in quadrupeds) muscles of upper limbs. It depends on the muscle or neuromuscular spindle : a fusiform end organ found between skeletal muscle fibers and acting as a mechanoreceptor; the muscle spindles are arranged in parallel with muscle fibers, and respond to passive stretch of the muscle but cease to discharge if the muscle contracts isotonically, thus signaling muscle length


• epilemmal endings : sensory nerve endings in striated muscle in which the nerve endings are in close contact with the muscle fibers.
• primary or annulospiral endings : wide, ribbon-like sensory nerve endings wrapped around the center of intrafusal fibers of a muscle spindle
• secondary or flower-spray endings : branched sensory nerve endings on intrafusal fibers of muscle spindles; their axons are more slender than those of annulospiral endings and they are at more peripheral locations or are confined to nuclear fibers
• Weissmann's bundle : the bundle of modified striated muscle fibers (Weissmann's intrafusal fibers) which, surrounded by fluid and enclosed in a connective tissue envelope, compose the muscle spindle
• nuclear bag fiber : an intrafusal fiber that contains a nuclear bag; it is longer and thicker and contracts more slowly than a nuclear chain fiber.
• nuclear chain fiber : an intrafusal fiber that contains a nuclear chain; it is shorter and thinner and contracts more rapidly than a nuclear bag fiber
g regulation by superior centres serves to compensate disallinement between projected a enlenthnement (whose reference level is modulated by g regulation) and that effectively realized. All afferences directed to a motor neurons also reach g motor neurons, except those coming from neuromuscular spindles. Both affererent fiber types increase their discharge frequency in the static phase after stretching, signaling the increased length of the muscle. Only the Aa/Ia fibers (that innervate also the nuclear bag fibers, which have particular sliding properties) increase their discharge frequency also in the dynamic phase of stretching, whose velocity is directly related with the intensity of the induced vibration. At the contraction of the extrafusal fibers the spindle remains sensitive thanks to a-g coactivation : the synchronism is only at the end (a motor neurons are excited later than g neurons but conduce action potentials faster). Such length negative feedback appears only in Aves. None of the 2 kinds of afferences discharges at contraction of extrafusal (such a discharge occurs in spindles from stretched antagonist muscle(s))

Actually also static nuclear bag fibers exist : they are innervated by static g-motoneurons and tonic flower spray endings Ab/II.
• idiomuscular reflex : tapping of muscle produces contraction of muscle itself; absent in advanced amyotrophia
• "inverse" myotatic reflex / stretching inverse reflex depends on Golgi's corpuscle, tendon organ or spindle / neurotendinous organ or spindle (an encapsulated nerve ending found in tendons of mammalian muscles and acting as a mechanoreceptor; arranged in series with the muscle, it is sensitive to mechanical distortion induced by either passive stretch of the tendon or isometric contraction of the muscle and thus signals muscle tension, being the receptor responsible for the lengthening reaction, or clasp-knife reflex)
• paciniform corpuscles or receptors : rapidly adapting lamellar nerve endings (corpuscula lamellosa) that are more elongated and have fewer laminae than pacinian corpuscles; found in the vibrissae and epidermis of the nose, in joint capsules, in aponeuroses, and at myotendinous junctions associated with Golgi tendon organs. They respond to muscle stretch and light pressure
Receptors increase frequency discharge with increasing tension, but they are more sensitive to muscular contraction (either isotonic or isometric) than passive stretching. This is a tension negative feedback system, unless external resistances (assessed as articular or low-threshold cutaneous afferences) supervenes.




..., but also brainstem (brainstem reflexes, whose absence is one criterion of coma, and, if prolonged, brain death) ... :
• midbrain : light or pupillary reflex
• pons :
• spontaneous and reflexed ocular movements
• corneal reflex
• bulb :
• vestibulo-ocular reflex
• pharyngeal reflex
• control of respiration
• cough reflex
• midbrain, pons & bulb :
• conjugate horizontal eyeball movements (depending on medial longitudinal fasciculus)
• oculocephalogyric reflex
.... and cerebral cortex. They are unvoluntary, but sometimes may be inhibited by will. In spinal cord the following rules :
• reciprocal inhibition between antagonist muscles
• crossed innervation between antimers
• a-g coactivation
Among both medial and lateral motor neurons, those innervating flexor muscles are more ventral than those innervating extensor muscles.
The second motor neuron is autonomous in reflex movements (negatively modulated by corticospinal tract fibers), being a part of diastaltic arch of reflexes : a reflected action or movement with segmental meaning (myelomeres) when in spinal cord; the sum total of any particular involuntary activity
• peripheral motoneuron : in a reflex arc, a motoneuron that receives impulses from interneurons
• reflex center : any center in the brain or spinal cord in which a sensory impression is changed into a motor impulse
• peripheral sensory neuron : in a reflex arc, a sensory neuron whose fibers end at synapses with interneurons
• central excitatory state : a condition in which there is stored up in a reflex center of the spinal cord a number of stimuli which do not reveal themselves in reflex response
• local excitatory state : the condition of a nerve produced by an ineffectual stimulus.
• deep reflexes are monosynaptic reflexes
• tendon jerk reaction or reflex : involuntary contraction of a muscle after brief stretching caused by percussion of its tendon
• masseterine reflex (pontine reflexogenic centre) : sudden chin percussion produces contraction of upper jaw elevator muscles
• Theimich's lip sign : a contraction of orbicularis oculi muscle (protrusion or pouting of the lips) elicited by tapping the orbicularis oris muscle.
• biceps reflex (C5 and C6) : tapping of biceps tendon (through the finger of the examiner) produces contraction of the biceps muscle via the musculocutaneous nerve and hence flexion of the elbow
• elbow or triceps reflex or jerk (C7) : tapping the tendon of the muscle 3 cm before the olecranon with the arm flexed and fully supported and relaxed produces contraction of the belly of the triceps muscle via the radial nerve (slight extension of the forearm over the arm)
• patellar reflex / knee jerk reflex / quadriceps jerk or reflex (L4) : tapping of the patellar ligament produces contraction of the quadriceps via the femural nerve (extension of the leg over the thigh)
• Jendrassik's maneuver : a procedure for emphasizing the patellar reflex: the patient hooks his hands together by the flexed fingers and pulls apart as hard as he can.
• Schreiber's maneuver : rubbing of the inner side of the upper part of the thigh while testing for patellar reflex.
• patelloadductor reflex / McCormac's reflex : crossed adduction of the thigh produced by tapping the quadriceps tendon as in the patellar reflex
• triceps surae jerk or reflex / Achilles tendon reflex or jerk / ankle jerk or reflex (L5, S1 and S2) : plantar flexion of the foot caused by a twitchlike contraction of the triceps surae muscle via the sciatic internal popliteal (tibial) nerve, elicited by a tap on the Achilles tendon preferably while the patient kneels on a bed or chair, the feet hanging free over the edge (alternatively supine patient with extrarotated thigh and mildly flexed leg)
• osteoperiosteal reflex : contraction of a muscle after tapping of a nearby bone that lies just below the surface of the skin
• radio-flexor or stiloradial reflex (C5-C6) : tapping on styloid apophysis of the radius 3 cm before the wrist (maintaining the forearm semiflexed on arm) produces contraction of supinator longus, biceps and anterior brachial muscles (flexion of the forearm over arm) via the radial nerve; when the fingers flex as well, it indicates hyperreflexia.
• cubito-pronator or ulnar reflex (C7-T1) : tapping of styloid apophysis of the dorsal side of ulna (with forearm semiflexed over arm and hand in mild supination) produces contration of pronator teres muscle (pronation of the hand) via the ulnar nerve
• mediopubic reflex (T6-L2) : tapping of pubis produces adduction of thighs and contraction of recti abdominis muscles
• tibioadductor reflex : tapping of the tibia on the inner side of the leg results either in homolateral adduction of the leg or crossed adduction from side to side.
• medioplantar reflex : tapping of foot sole produces extension of foot
• articular reflexes
• superficial reflexes : any withdrawal polysynaptic reflex elicited by noxious or tactile stimulation of the skin, cornea, or mucous membrane, traveling in poorly myelinated (slow conduction) afferent nerve fibers.
• skin reflex : a reflex occurring on stimulation of the skin; absent in pyramidal tract lesions
• infraspinatus reflex :tapping a spot over the shoulder blade on a line bisecting the angle formed by the spine of the bone and its inner border causes outward rotation of the arm and straightening of the elbow
• interscapular reflex / scapular reflex : a stimulus applied between the scapulae contracts the scapular muscles
• abdominal reflexes : contractions of the homolateral upper abdominal muscles (recti, obliqui, and transverse muscles) on scratching of the abdominal wall from the external toward the internal area. Absence may be due to flaccid (parous females) or obese abdomen.
• upper abdominal or epigastric reflex (T6, T7, and T8) : contraction of the abdominal muscles caused by stimulating the skin of the epigastrium or over the fifth and sixth intercostal spaces near the axilla.
• intermediate abdominal or mesogastric reflex (T9 and T10)
• lower abdominal or hypogastric reflex (T11 and T12)
• obliquus reflex : stimulation of the skin below Poupart's ligament contracts a part of the external oblique muscle.
• Livierato's sign : vasoconstriction when the abdominal sympathetic nerve is irritated by striking the anterior abdomen along the xiphoumbilical line
• cremasteric reflex (L1-L2) : stimulation of the skin on the front and inner side of the upper thigh produces contraction of ipsilateral cremasteric muscle (retraction of the testis)
• Brissaud's reflex : contraction of the tensor muscle of fascia lata on tickling the sole.
• plantar reflex / sole reflex (L4-S2) : with the external border of the foot ling on the bed (eextrarotated thigh and mildly flexed leg), irritation of the lateral border of the sole of the foot and then all the distal metatarsal heads causes plantar flexion of all the toes. The pyramidal tract facilitates motor neurons innervating flexor neurons and masks the avoidant reflex. Before introduction of shoes, plantar reflex served to ensure adhesion of foot to rickety lands (unless it received painful stimuli) : it is an evolutionarily conserved phenotypic trait which confers selective advantage by allow environmental exploration
• Hirschberg's sign / adductor reflex of foot : adduction, inversion, and slight plantar flexion of the foot on stroking the inner aspect (not the sole) of the foot from the great toe to the heel
• Babkin reflex : pressure by the examiner's thumbs on the palms of both hands of the infant results in opening of the infant's mouth; it is elicited in many newborn infants, normal and abnormal, except when lethargic or comatose
• Barkman's reflex : contraction of the rectus abdominis muscle on the same side after stimulation of the skin just below one of the nipples
• bulbospongiosus reflex : contraction of the bulbospongiosus muscle in response to a tap on the dorsum of the penis
• ciliospinal reflex / Parrot's sign : painful stimulation of the skin of the neck, face, or another body part dilates the ipsilateral pupil
• Geigel's reflex / inguinal reflex : a reflex in the female corresponding to the cremasteric reflex in the male; i.e., on stroking of the inner anterior aspect of the upper thigh there is a contraction of the muscular fibers at the upper edge of Poupart's ligament
• hypogastric reflex / Bekhterev's reflex : contraction of the muscles of the lower abdomen on stroking the skin of the inner surface of the thigh
• gluteal reflex : a stroke over the skin of the buttock contracts the glutei muscles
• dartos reflex / scrotal reflex : vermicular contractions of the dartos muscle when a cold or stroking stimulus is applied to the perineum
• front-tap reflex : a tap on the skin muscles of the extended leg contracts the gastrocnemius.
• Morley's peritoneocutaneous reflex : when any of the cerebrospinal nerve endings in the peritoneum or subperitoneal tissues are irritated, pain will be referred to the corresponding segmental skin area.
• anal reflex (S4 and S5) : contraction of the anal sphincter and levator ani muscles on scratching or other irritation of the skin of the anus.
• mucosal reflexes
• corneal reflexes / corneal-conjunctival or trigeminofacial reflex (pressure with cotton over a scleral conjunctiva while the patient is looking upward and at the opposite side (to prevent visual mimicking) causes bilateral contraction of eyelid constrictor muscle via trigeminal (V) nerve => facial (VII) nerve)
• corneomandibular reflex : movement of the lower jaw toward the side opposite the eye whose cornea is lightly touched, the mouth being open
• corneomental reflex : unilateral wrinkling of the muscles of the chin when pressure is applied to the cornea.
• pharyngeal or gag reflex (IX => pontine reflexogenic center => IX and X cranial nerve) : touching the back of a half soft palate, tonsil or pharynx produces bilateral retraction of the tongue, elevation of the soft palate, and contraction of the constrictor muscle of the pharynx via the glossopharyngeal (IX) nerve; often with conatus of vomiting
• bregmocardiac reflex : pressure upon the bregmatic fontanelle slows the action of the heart
• Haab's cerebral cortex reflex : bilateral pupillary contraction when the patient sits in a darkened room, and without accommodation or convergence directs attention to a bright object already within the field of vision
• Mayer's finger-thumb or basal joint reflex : passive flexion of the metacarpophalangeal joint of one of the fingers causes flexion of the basal joint and extension of the terminal joint of the thumb
• hypochondrial reflex : sudden inspiration caused by quick pressure beneath the lower border of the ribs
• Kehrer's or Kisch's reflex : closure of the eye as a result of tactile or thermal stimulation of the deepest part of the external auditory meatus and tympanum
• Kocher's testicular compression reflex : contraction of the abdominal muscle on compression of the testicle
• Landau reflex : when an infant is held in the prone position, the entire body forms a convex upward arc; gentle pressure on the head or gravity flexes the neck and hip, reversing the arc
• Bekhterev's nasal reflex : tickling of the mucosa of the nasal cavity produces contraction of the facial muscles on the same side of the face
• nasomental reflex : contraction of the mentalis muscle on tapping the side of the nose with a percussion hammer.
• neck righting reflex : rotation of the trunk in the direction in which the head of the supine infant is turned; this reflex is absent or decreased in infants with spasticity.
• Marinesco-Radovici palm-chin or palmomental reflex or sign : twitching of the chin produced by stimulating (scratching) the palm
• pectoral reflex : the subject's arm is placed half way between adduction and abduction and the examiner's finger in the muscle tendon near the humerus: a sharp blow of the finger elicits adduction and slight internal rotation.
• Philippson's reflex : excitation of the knee extensor in one leg induced by inhibition in the knee extensor of the other leg.
• pilomotor reflex : the production of goose flesh on stroking the skin; trichographism.
• placing reflex : flexion followed by extension of the leg when the infant is held erect and the dorsum of the foot is drawn along the under edge of a table top; it is obtainable in the normal infant up to the age of 6 weeks.
• Remak's femoral reflex : plantar flexion of the first three toes and sometimes of the foot, with extension of the knee on stroking of the upper anterior surface of the thigh, a sign of a spinal cord lesion
• rooting reflex : a reflex in the newborn in which stimulation of the side of the cheek or the upper or lower lip causes the infant to turn his mouth and face to the stimulus.
• scapulohumeral reflex : adduction with outward rotation of the humerus produced by percussing along the inner edge of the scapula.
• scratch reflex : a spinal reflex by which an itch or other irritation of the skin causes a nearby body part to move over and briskly rub the affected area.
• Snellen's auriculocervical nerve reflex : unilateral congestion of the ear upon stimulation of the distal end of the divided great auricular nerve
• stepping reflex : movements of progression elicited when the infant is held upright and inclined forward with the soles of the feet touching a flat surface; it is obtainable in the normal infant up to the age of 6 weeks.
• Stookey's reflex : with the leg semiflexed at the knee, the tendons of the semimembranosus and the semitendinosus muscles are tapped: flexion of the leg results.
• Strümpell's reflex : leg movement with adduction of the foot produced by stroking the thigh or abdomen.
• suprapatellar reflex : with the subject's leg extended the index finger of the examiner is crooked above the patella and is struck; the result is a kick-back of the patella.
• suprapubic reflex : stroking the abdomen above Poupart's ligament causes deviation of the linea alba toward the side that is stroked
• threat reflex : sudden closure of the eyes at a sign of danger
• toe reflex : strong flexion of the great toe flexes all the muscles of the lower extremity in pathologic states accompanied by hyperreflexia.
• tonic neck reflex : a reflex in the newborn consisting of extension of the arm and sometimes of the leg on the side to which the head is forcibly turned, with flexion of the contralateral limbs
• conditioned response / trained reflex : a response evoked by a conditioned stimulus; one occurring to a stimulus that was incapable of evoking it before conditioning.
• habituation : extinction or decrease of a conditioned reflex over time by repetition of the conditioned stimulus.
• unconditioned response / inborn or unconditioned reflex : a response elicited spontaneously by an unconditioned stimulus; an unlearned response, i.e., one that occurs naturally
• vagus reflex : abnormal sensitiveness to pressure over the course of the vagus nerve.
• vascular or vasopressor reflex : vasoconstriction with a rise in blood pressure caused by neural stimulation.
• vertebra prominens reflex : pressure upon the last cervical vertebra of an animal reduces the tone of all four limbs.
• virile reflex / Hughes' reflux : in the flaccid penis, a sudden reflexive downward jerk elicited by pulling upward the foreskin or glans penis
• zygomatic reflex : lateral motion of the lower jaw to the percussed side on percussion over the zygoma.
• Moro's embrace or startle reflex : flexion of an infant's thighs and knees, fanning and then clenching of the fingers, with arms first thrown outward then brought together as if in an embrace, produced by a sudden stimulus such as the table being struck next to the child, or by sudden extension of the neck when the head is allowed to fall backward or the child is pulled up by both hands from a lying position and then let go. It is seen normally in infants up to 3 to 4 months of age
• visceral reflex : that in which the stimulus is set up by some state of an internal organ.
• viscerocardiac reflex : reflex alteration in cardiac rhythm or contractility caused by visceral excitation.
• visceromotor reflex : contraction of abdominal muscles (abdominal rigidity) over a diseased viscus.
• viscerosensory reflex : a response or reaction to pressure on some part of the body due to disease of some internal organ.
• viscerotrophic reflex : degeneration of any peripheral tissue as a result of chronic inflammation of any of the viscera.
• rhythmic or automatic movement : cyclically repeated movements requiring will to be initiated, modulated, and terminaed (e.g. are walking, swimming, flying, breathing, chewing). Reflex or voluntary movements can overlap. They are expecially associated with brainstem
• mediated by lateral systems (in spinal cords found in dorsal parts of lateral columns) => voluntary movements in distal contralateral muscles with small motor units (limbs, face, tongue, larynx) : nonstereotypes strategic choices dependent on genetic background and past and current experiences (aesthetic needs, circumstances, ...). Voluntary movements are expecially associated with cerebral cortex (hence present only in Mammalia). E.g. are writing, speaking, mimicking, oppose the thumb

• Siegel, George J.; Agranoff, Bernard W.; Albers, R. Wayne; Fisher, Stephen K.; Uhler, Michael D. : Basic Neurochemistry, Molecular, Cellular, and Medical Aspects. 6^th ed. Philadelphia, Pennsylvania: Lippincott,Williams & Wilkins;  ©1999. ISBN 0 397 51820 X [free at  NCBI BookShelf !]
• Purves, Dale; Augustine, George J.; Fitzpatrick, David; Katz, Lawrence C.; LaMantia, Anthony-Samuel; McNamara, James O.; Williams, S. Mark : Neuroscience. 2nd ed.; Sunderland (MA): Sinauer Associates, Inc.; 2001. [free at  NCBI BookShelf !]
• Eric R.Kandel, James H.Schwartz : Principles of Neural Science, by Elsevier Science Publishing Co.
• Encyclopedia of Cognitive Science by Nature Publishing Group
• Nature Insight Molecular sensing in Nature Vol.413, 13 September 2001

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