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
• 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 pe