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161 Cards in this Set

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Circle of Willis
The anastomotic polygon at the base of the brain, consisting of parts of theinternal carotid, anterior cerebral, and posterior cerebral arteries, interconnected by the anterior and posterior communicating arteries.
ACA
The anastomotic polygon at the base of the brain, consisting of parts of theinternal carotid, anterior cerebral, and posterior cerebral arteries, interconnected by the anterior and posterior communicating arteries.
Anterior Communicating Artery
A short vessel at the anterior end of the circle of Willis interconnecting the two anterior cerebral arteries just in front of the optic chiasm; occasionally it may be very small or, very rarely, absent.
Internal Carotid Artery
A large distributing artery, originating from the bifurcation of the common carotid artery and running cranially in the neck to enter the base of the skull and eventually the cranial vault. The internal carotid artery branches at the circle of Willis into anterior and middle cerebral arteries. The two internal carotids account for 85% of cerebral blood flow and thus supply most of the blood to the brain.
MCA
The more posterior of the two terminal branches of the internal carotid. The middle cerebral artery runs laterally beneath the basal forebrain to reach the insula, where many branches arise and exit from the lateral sulcus. It supplies the insula, most of the lateral surface of the cerebral hemisphere, and the anterior tip of the temporal lobe.
Posterior Communicating Artery
A short vessel connecting the posterior cerebral artery to the internal carotid, thereby forming one link in the circle of Willis. Normally pressures in the internal carotid and posterior cerebral arteries are balanced so that little or no blood flows around the circle, but if one vessel is occluded the posterior communicating artery may allow anastomotic flow and thus prevent neural damage.
P. Cerebral Artery
A short vessel connecting the posterior cerebral artery to the internal carotid, thereby forming one link in the circle of Willis. Normally pressures in the internal carotid and posterior cerebral arteries are balanced so that little or no blood flows around the circle, but if one vessel is occluded the posterior communicating artery may allow anastomotic flow and thus prevent neural damage.
Basilar Artery
A large vessel formed by union of the two vertebral arteries. The basilar artery runs upward along the anterior median surface of the pons and gives rise to many perforating branches that supply the pons and caudal midbrain. It also gives rise to the anterior inferior cerebellar artery and the superior cerebellar artery before bifurcating at the level of the midbrain into the two posterior cerebral arteries.
S. cerebellar artery
A branch of the basilar artery that arises just caudal to its bifurcation. Long circumferential branches supply the superior surface of the cerebellum, and shorter branches supply much of the rostral pons and caudal midbrain.
A.I.Cerebellar Artery (AICA)
A long, circumferential branch of the basilar artery arising just above the union of the two vertebrals. It supplies anterior regions of the inferior cerebellar surface, including the flocculus, and parts of the caudal pons.
P.I.Cerebellar Artery (PICA)
A long, circumferential branch of the vertebral artery, supplying much of the inferior surface of the cerebellum; en route it sends shorter branches to the choroid plexus of the fourth ventricle and to much of the lateral medulla.
Vertebral Artery
One of the two major arteries that supply each side of the CNS (see also internal carotid artery). The vertebral artery originates as the first branch of the subclavian, runs cranially through foramina in cervical vertebrae, enters the base of the skull through the foramen magnum, and ascends along the medulla. At the pontomedullary junction it unites with its contralateral counterpart to form the basilar artery. The vertebral artery and its posterior inferior cerebellar branch (PICA) supply blood to the medulla and inferior part of the cerebellum, and it supplies the cervical spinal cord via the posterior and anterior spinal arteries.
Lateral Fissure (Sylvian)
A long, deep sulcus on the lateral aspect of each cerebral hemisphere resulting from downward and forward expansion of the temporal lobe during fetal development. The insula lies hidden within the depths of this sulcus, which separates the temporal lobe from the frontal and parietal lobes and provides a route by which the middle cerebral artery accesses the lateral convexity.
Central Sulcus (of Rolando)
An anatomically and functionally important infolding of the cerebral hemisphere, beginning just medial to the superior border of the hemisphere, proceeding over its superior margin, and descending obliquely forward almost to the lateral sulcus. The central sulcus is the boundary between the frontal and parietal lobes, and the transition zone between primary motor and primary somatosensory cortex.
Frontal Lobe
The most anterior lobe of each cerebral hemisphere. The frontal lobe includes motor, premotor, and supplementary motor cortex, an extensive prefrontal region, and a large expanse of orbital cortex. The latter two regions have access via long association fibers to all other lobes and also to the limbic system, and are important (in a poorly understood way) in working memory, regulating emotional tone, prioritizing bodily/environmental demands, and stabilizing short- and long-range goal-directed activity.
Parietal Lobe
A cerebral lobe bounded by the frontal, temporal, and occipital lobes on the lateral surface of each hemisphere, and by the frontal, limbic, and occipital lobes on the medial surface. The parietal lobe contains primary somatosensory cortex in the postcentral gyrus, areas involved in language comprehension (in the inferior parietal lobule, usually on the left), and regions involved in complex aspects of spatial orientation and perception.
Temporal Lobe
The most inferior lobe of each cerebral hemisphere, inferior to the lateral sulcus and anterior to the occipital lobe. The temporal lobe includes auditory sensory and association cortex, part of posterior language cortex, visual and higher-order association cortex, primary and association olfactory cortex, the amygdala, and the hippocampus. (The parahippocampal gyrus, a major part of the limbic lobe, is also commonly referred to as part of the medial temporal lobe.)
Occipital Lobe
The most posterior lobe of each cerebral hemisphere. The occipital lobe includes the primary visual cortex in the banks of the calcarine sulcus and adjoining areas of visual association cortex.
Precentral gyrus
A vertically oriented convolution of the frontal lobe immediately anterior to the central sulcus. The precentral gyrus is the site of primary motor cortex (Brodmann's area 4).
Postcentral gyrus
A vertically oriented convolution of the parietal lobe immediately posterior to the central sulcus. The postcentral gyrus is the site of primary somatosensory cortex (Brodmann's areas 3, 1, and 2).
Broca's speech area
The opercular and triangular parts of the inferior frontal gyrus, usually on the left. Broca's area has traditionally been considered critical for the production of language, but more recent work indicates that other structures such as the insula and the head of the caudate nucleus may be at least equally important.
Wernicke's speech area
The posterior part of the superior temporal gyrus (Brodmann's area 22), usually on the left. Wernicke's area, along with the angular and supramarginal gyri and parts of the middle temporal gyrus, is important for the comprehension of language.
Olfactory bulb/tract
Projections from olfactory bulb neurons (mitral and tufted cells) to olfactory (piriform) cortex and the amygdala. The olfactory tract also conveys modulatory efferents traveling from deeper olfactory centers back to the olfactory bulb.
Optic nerve
The second cranial nerve, containing axons of the various types of retinal ganglion cells projecting to the lateral geniculate nucleus of the thalamus, superior colliculus, pretectal area, suprachiasmatic nucleus of the hypothalamus, and a few other sites.
Optic chiasm
The site at which optic nerve fibers from ganglion cells in the nasal half of each retina decussate, so that each optic tract contains fibers arising in the temporal retina of the ipsilateral eye and the nasal retina of the opposite eye.
Optic tract
Axons of ganglion cells from corresponding halves of each retina (i.e., temporal half of the ipsilateral retina and nasal half of the contralateral retina) on their way to the lateral geniculate nucleus, superior colliculus, pretectal area, and a few other sites.
Mammilary Body
A prominent component of the posterior hypothalamus. The mammillary body receives afferents from the hippocampus (chiefly the subiculum) via the fornix, and sends efferents to the anterior nucleus of the thalamus via the mammillothalamic tract. This is part of a historic neural circuit proposed by James Papez in 1937 as an anatomical substrate for emotion. Although it was derided by some then and viewed as simplistic by others now, the Papez circuit—a grand loop from hippocampus through hypothalamus, thalamus, and neocortex back to hippocampus again—was unquestionably the impetus for the decades of research that led to the limbic system concept of today.
Pons
The second of the three parts of the brainstem, continuous rostrally with the midbrain and caudally with the medulla. The pons is overlain by the cerebellum and includes an enlarged basal region (see basal pons).
cerebellum
The second of the three parts of the brainstem, continuous rostrally with the midbrain and caudally with the medulla. The pons is overlain by the cerebellum and includes an enlarged basal region (see basal pons).
Olives
Protuberance on the lateral aspect of the medulla, just dorsolateral to the pyramid, caused by the underlying inferior olivary nucleus. (GREY MATTER = NUCLEI)
Pyramids
Corticospinal fibers from the ipsilateral precentral gyrus and adjacent areas of cerebral cortex, forming a prominent fiber bundle (roughly triangular in cross section, which gave rise to the name) on the ventral surface of the medulla.
Decussation of the pyramids
The site, located at the spinomedullary junction, at which most fibers in each pyramid cross the midline to form the contralateral lateral corticospinal tract. (WHITE MATTER = AXONS)
Uncus
A medial protuberance from the anterior end of the parahippocampal gyrus caused by the underlying amygdala. The proximity of its surface to the adjacent cerebral peduncle can cause clinical problems during cerebral edema or as a result of space-occupying masses, because the uncus can herniate through the tentorial notch and compress the midbrain.
Medulla Oblongata
The most caudal of the three subdivisions of the brainstem, continuous rostrally with the pons and caudally with the spinal cord. This small structure is important out of proportion to its size: it is crucial to vital functions (respiratory, cardiovascular, visceral activity) and other integrative activities; most sensory and motor tracts of the CNS run rostrally and caudally through it. (Closed & Open...)
Obex
Apex of the V-shaped caudal fourth ventricle, where the ventricle narrows into the central canal of the caudal medulla and spinal cord. (decussation of fibers happens at this 'V')
Fourth ventricle
The most caudal of the brain ventricles, shaped like a tent with a peaked roof protruding into the overlying cerebellum and a diamond-shaped floor formed by the upper surface of the pons and rostral medulla; confluent with the third ventricle via the cerebral aqueduct and open to subarachnoid space through three foramina: one median aperture (of Magendie) and two lateral apertures (of Luschka).
Pontine tegmentum
A general anatomical term for the area anterior to the ventricular spaces of the medulla, pons, and midbrain. „Tegmentum” is a useful umbrella term (Latin for „covering”) for all structures covering the basal components of the brainstem (pyramids, basal pons, cerebral peduncles) and includes the reticular formation, nuclei of cranial nerves, most ascending and descending tracts (except the corticospinal tract), the red nuclei, and substantia nigra.
Basal pons
A mass of gray and white matter, oriented transversely and filled with transversely and longitudinally coursing fibers, on the anterior surface of the pons. The basal pons looks like a bridge (for which the pons was named) between the two cerebellar hemispheres, but in fact it is a key link between the cerebrum and cerebellum: corticopontine fibers end in its scattered pontine nuclei, which in turn project across the midline into the cerebellum via the middle cerebellar peduncle.
Cerebral aqueduct (Sylvius)
The narrow channel through the midbrain connecting the third and fourth ventricles. The aqueduct is a remnant of the lumen of the embryonic mesencephalon; it lacks a choroid plexus and serves only as a conduit for CSF descending through the ventricular system (its stenosis or obstruction is the most common cause of congenital hydrocephalus).
Midbrain (mesencephalon)
The most rostral of the three subdivisions of the brainstem. The midbrain remains tubular in plan but features a great variety of structures: the superior and inferior colliculi in its roof (tectum), aqueduct and periaqueductal gray, oculomotor and trochlear nuclei and pretectal area, upper part of the reticular formation, red nuclei, substantia nigra, and cerebral peduncles. Like the medulla, a small region of enormous importance.
tectum
The superior and inferior colliculi, the „roof” of the midbrain; posterior of brain stem superior to midbrain.
tegmentum
A general anatomical term for the area anterior to the ventricular spaces of the medulla, pons, and midbrain. „Tegmentum” is a useful umbrella term (Latin for „covering”) for all structures covering the basal components of the brainstem (pyramids, basal pons, cerebral peduncles) and includes the reticular formation, nuclei of cranial nerves, most ascending and descending tracts (except the corticospinal tract), the red nuclei, and substantia nigra.
superior colliculus (=hill)
A large, rounded mass of gray matter in the roof of the rostral midbrain. The superior colliculus receives afferents from the retina and visual cortex, sends efferents to the pulvinar and other structures, and plays a role in directing visual attention and controlling eye movements. LARGER & Posterior
inferior colliculus (=hill)
A large, rounded mass of gray matter in the roof of the caudal midbrain. The inferior colliculus is a major link in the auditory system, receiving the lateral lemniscus and giving rise to the brachium of the inferior colliculus, which in turn conveys auditory fibers to the medial geniculate nucleus of the thalamus. SMALLER & Posterior
pineal body
A dorsal outgrowth of the diencephalon, protruding from the third ventricle immediately above and posterior to the paired habenular nuclei. The pineal is an endocrine gland important in seasonal cycles of some animals; in humans it secretes melatonin with a circadian rhythm and participates in adjusting the phase of the rhythm.
thalamus
A collection of nuclei that collectively are the source of most extrinsic afferents to the cerebral cortex. Some thalamic nuclei (relay nuclei) receive distinct input bundles and project to discrete functional areas of the cerebral cortex. Others (association nuclei) are primarily interconnected with association cortex. Still others have diffuse cortical projections, and one has no projections to the cortex at all: from anteromedial clockwise = Anterior, Ventral anterior, Ventrolateral, Ventral posterolateral, Pulvinar, Dorsomedial
hypothalamus
"The most inferior of the four divisions of the diencephalon, the hypothalamus plays a major role in orchestrating visceral and drive-related activities. It has three general zones:
interventricular foramen (of Monro)
The narrow orifice between each lateral ventricle and the third ventricle.
third ventricle
The single, median, vertically oriented cavity of the diencephalon, separating the thalamus and hypothalamus of the two hemispheres. The third ventricle is confluent anteriorly with both lateral ventricles through the interventricular foramina and posteriorly with the fourth ventricle through the aqueduct. It has four small outpocketings:
cerebral cortex
The 1.5- to 4.5-mm thick layer of gray matter that covers the surface of each cerebral hemisphere. The cerebral cortex includes olfactory areas (paleocortex) and the hippocampus (archicortex), but most of it is six-layered neocortex. The neocortex is made up of a huge number of columnar functional modules, organized into primary sensory and motor areas, unimodal association areas, multimodal association areas, and limbic areas.
corpus callosum
(Latin for „hard body”), a massive curvilinear bridge of commissural fibers, shaped in sagittal sections like an overturned canoe. The corpus callosum interconnects most cortical areas of the two cerebral hemispheres and serves to join them functionally, providing the substrate for a unitary consciousness.
anterior commissure
A small, sharply defined bundle of commissural fibers between the rostrum of the corpus callosum (to which it is closely related developmentally) and the columns of the fornix as they turn down toward the hypothalamus; a few inconspicuous anterior fibers interconnect olfactory structures, while its many large posterior fibers link the temporal cortex of the two sides of the brain.
lamina terminalis
A thin membrane at the anterior end of the third ventricle, curving down from the rostrum of the corpus callosum to the optic chiasm and corresponding (roughly, if not precisely) to the rostral end of the neural tube. The lamina terminalis connects the two telencephalic vesicles of the embryonic forebrain and provides a route through which commissural fibers that will later comprise the anterior commissure and corpus callosum begin to grow.
choroid plexus
Long, grapevine-like, highly convoluted and vascularized strands in the lateral, third, and fourth ventricles where most of the CSF is produced.
gracile tubercle
A conspicuous swelling, just caudal to the obex, located dorsomedially on the medulla overlying the nucleus gracilis, which mediates that part of the posterior column–medial lemniscus pathway carrying tactile and proprioceptive information from the leg and lower body.
cuneate tubercle
A conspicuous swelling on the dorsolateral aspect of the mid-medulla overlying the cuneate nucleus, which mediates that part of the posterior column-medial lemniscus pathway carrying tactile and proprioceptive information from the arm and upper body.
hypoglossal trigone
A triangular elevation in the floor of the caudal fourth ventricle formed by the underlying hypoglossal nucleus.
vagal trigone (dorsal motor nucleus of the vagus)
A small elevation in the floor of the caudal fourth ventricle with boundaries forming a triangle just lateral to the hypoglossal trigone. Each vagal trigone is a fusiform swelling produced by the underlying dorsal motor nucleus of the vagus.
facial colliculus
A swelling in the floor of the fourth ventricle in the caudal pons, caused by the underlying internal genu of the facial nerve looping around the abducens nucleus.
middle cerebellar peduncle
The largest of the cerebellar peduncles, containing fibers from contralateral pontine nuclei that end as mossy fibers in almost all areas of cerebellar cortex. Sometimes referred to as the brachium pontis (the „arm of the pons”).
superior cerebellar peduncle
The major efferent route from the cerebellum, containing projections from deep cerebellar nuclei on their way to the contralateral red nucleus and thalamus (VL/VA). Sometimes referred to as the brachium conjunctivum (a „joined-together arm,” named for its course through a decussation with its contralateral counterpart). A descending limb leaves the superior cerebellar peduncle near its decussation and projects to the contralateral inferior olivary nucleus.
pia mater
The innermost and thinnest of the three meninges, attached to the surface of the CNS and connected to the arachnoid by arachnoid trabeculae.
arachnoid mater
The thin meningeal layer that lines and is attached to the dura mater, and is interconnected with the pia mater by arachnoid trabeculae.
dura mater
The outermost and most substantial of the three meningeal layers. Intracranial dura mater is firmly attached to the inside of the skull and serves as its periosteum. Spinal dura mater forms a sac, separate from the vertebral periosteum, within which the spinal cord is suspended. See also epidural space, subdural space, and venous sinus.
falx cerebri
The sickle-shaped dural septum between the two cerebral hemispheres.
tentorium cerebelli
The dural septum between the cerebellum and the inferior surfaces of the occipital and temporal lobes. The midbrain passes through a midline notch in the tentorium; this notch provides an aperture through which parts of the medial temporal lobe can herniate in response to expanding masses.
S. sagittal sinus
A prominent venous sinus in the attached edge of the falx cerebri. Venous blood traveling posteriorly in this sinus meets up with blood from the straight sinus at the confluence of the sinuses.
I. sagittal sinus
A large, unpaired vessel arising in the superior cistern by union of the two internal cerebral veins. During its short course it receives the basal veins (of Rosenthal), then turns superiorly around the splenium of the corpus callosum and joins the inferior sagittal sinus to form the straight sinus. The great vein is a key conduit in the deep venous drainage of the brain.
Confluence of sinuses
The meeting point, near the internal occipital protuberance, where venous blood arrives through the straight and superior sagittal sinuses and leaves through the transverse sinuses.
Straight of sinus
The final recipient of blood flowing through deep cerebral veins. The straight sinus travels in the line of attachment of the falx cerebri and tentorium cerebelli and empties into the confluence of the sinuses.
Transverse sinus
The laterally directly sinus on each side in the attached edge of the tentorium cerebelli, conveying blood from the confluence of the sinuses to the sigmoid sinus.
Cavernous sinus
Superior petrosal sinus
Inferior petrosal sinus
sigmoid sinus
The continuation of each transverse sinus after it leaves the attached edge of the tentorium cerebelli. Named for the sinuous course it takes on the way to the internal jugular vein.
Internal jugular vein
notochord
mesoderm derived; induces the overlying ectoderm to form neural tube
neural tube
The tubular epithelial structure formed when the neural groove deepens, closes and detaches from the surface epithelium; the neural tube goes on to form the CNS.
neural crest
Cells near the crest of each neural fold that are not incorporated into the neural tube, but rather migrate widely, form most elements of the PNS, and contribute to many other structures:: sensory dorsal root ganglia, postganglionic autonomic neurons, Schwann cells, Chromaffin cells (adrenal)
optic vesicles
Pros: neural retina and pigment epithelium are products of this; the lens is induced from the surface ectoderm by this.
prosencephalon (Pros)
The most rostral of the three primary embryonic brain vesicles, giving rise to the cerebrum. The prosencephalon (forebrain) subsequently subdivides into the telencephalon and diencephalon.
mesencephalon (Mes)
The second of the three primary embryonic brain vesicles, the only one to remain undivided during subsequent development. See also midbrain.
rhombencephalon (Rhom)
The most caudal of the three primary embryonic brain vesicles. Named for the rhomboid shape of the fourth ventricle that develops within it, the rhombencephalon (hindbrain) subsequently subdivides into the metencephalon and myelencephalon.
telencephalon (Tele)
The most rostral of the five secondary embryonic brain vesicles. The paired telencephalic vesicles give rise to the cerebral hemispheres.
Diencephalon (Dien)
Literally the „in-between-brain,” the caudal subdivision of the embryonic forebrain, giving rise to the pineal gland, habenula, thalamus, subthalamic nucleus, retina, optic nerve and tract, hypothalamus, and neurohypophysis.
Metencephalon (Met)
The more rostral of the two secondary embryonic brain vesicles derived from the rhombencephalon; gives rise to the pons and cerebellum.
Myelencephalon (Mye)
The more caudal of the two secondary embryonic brain vesicles derived from the rhombencephalon; gives rise to the medulla.
cephalic flexure
The bend of about 80 degrees between the long axis of the brainstem and spinal cord and the anterior-posterior axis of the cerebrum: @ dien-mes juncture
ventricular zone
Cell division; contains nerublasts that are still mitotically active = closest to sulcus limitans (middle opening)
marginal zone
a cell-free zone in which the processes of the ventricular zone cells extend to contact the external surface of the cord.
intermediate zone
mantle zone; between the ventricular and marginal zones containing the post-mitotic & post-migratory neurons.
alar plate
dorsal; origin of sensory neurons throughout the spinal cord, medulla and pons
basal plate
ventral; origin of motor neurons in this region
roof plate
most dorsal portion of developing neural tube
floor plate
most ventral portion of developing neural tube
sulcus limitans
A longitudinal groove in the embryonic spinal cord and brainstem that separates the alar plate of gray matter (sensory nuclei) from the basal plate (motor nuclei). In adult brains it persists as a groove in the floor of the fourth ventricle that separates motor nuclei of cranial nerves (now medial to it) from sensory nuclei of cranial nerves.
ventral root
The anterior, motor root of a spinal nerve, coalescing from a variable number of unevenly spaced rootlets that depart the spinal cord along its anterolateral sulcus.
dorsal root
The posterior, sensory root of a spinal nerve, which divides into a variable number of regularly spaced rootlets that enter the spinal cord along its posterolateral sulcus.
dorsal root ganglia
nuclei of cell bodies where synapse occurs in dorsal root sensory afferent neurons
cervical cord
widest region of spinal cord; large amounts of white matter (many axon tracts) & expansion of ventral horn (efferent motor nuclei)
thoracic cord
ratio of white:gray is highest (many axon tracts) & ventral horn gray matter is small (only innvervates axial musculatrure) & more gray matter in lateral horn (preganglionic sympathetic neurons)
lumbar cord
highest ration gray: white (reduction in white matter, large size of many nuclei bodies)
sacral cord
coccygeal cord
dorsal median septum
Divides the dorsal region of the cord into equal halves - ascending axons of dorsal root ganglion sensory neurons
ventral median fissure
pronounced separation of the ventral cord into two halves
dorsal horn
Alar plate; sensory axons; laminae (thin plate, sheet); some are interneurons w/ local axon projections and others relay sensory input to higher levels of CNS
ventral horn
Basal plate; large motor neurons; clusters
intermediate cord
many interneurons relay sensory info to motor areas; between ventral and dorsal horns
lateral horn
small lateral extension of gray matter btw dorsal and ventral horns; only thoracic & upper lumbar segments of spinal cord; preganglionic sympathetic neurons
dorsal funiculus
dorsal columns; somatosensory tracts of white matter axons
lateral funiculus
largest white matter tract region; lateral corticospinal tract is largest descending tract & several ascending tracts
ventral funiculus
btw ventral median fissure & lateral funiculus, the ventral funiculus contains several small descending tracts
genu (CC)
The kneelike sharp anterior bend, containing fibers that lead to and from prefrontal cortex.
Splenium (CC)
The thick, rounded posterior bend, containing fibers to and from the occipital and temporal lobes
Basal Ganglia
A group of subcortical nuclei, most prominently including the striatum, globus pallidus, substantia nigra, and subthalamic nucleus, that collectively modulate the output of frontal cortex. Basal ganglia damage has traditionally been considered to cause disorders characterized by involuntary movements, difficulty initiating movement, and alterations in muscle tone (e.g., Parkinson's disease). However, damage to certain parts of the basal ganglia can cause disturbances of cognition and motivation instead.
Striatum
An inclusive term for the caudate nucleus, putamen, and ventral striatum. The striatum is the major point of entry into basal ganglia circuitry, receiving inputs from most or all cortical areas and projecting inhibitory outputs to the globus pallidus and substantia nigra (reticular part).
Caudate nucleus
The more medial part of the striatum, bulging into the lateral ventricle with its large head in the wall of the anterior horn, tapering body immediately behind, and long slender tail running posteriorly into the atrium and then anteriorly into the inferior horn. It is principally connected with prefrontal and other association areas of cortex, and involved more in cognitive functions and less directly in movement.
Putamen
(lenticular nucleus) The part of the striatum involved most prominently in the motor functions of the basal ganglia. The putamen receives afferents from cerebral cortex (primarily motor and somatosensory areas), and from the substantia nigra (compact part) and the centromedian nucleus of the thalamus. It projects efferents to the globus pallidus, which in turn projects via the thalamus (VA/VL) to premotor and supplementary motor areas. The putamen forms the outer component of the lenticular nucleus (the globus pallidus is the inner part).
Globus Pallidus
A wedge-shaped nucleus medial to the putamen that gives rise to most of the efferents from the basal ganglia.
Spectum Pellucidum
separates the two lateral ventricles at the midline
Insula
The original lateral surface of the embryonic telencephalic vesicle overlying an area of fusion with the diencephalon, forming in the adult a central lobeof the cerebral hemisphere, typically convoluted into about three short gyri (located more anteriorly) and two long gyri. With rapid cerebral expansion during fetal development, the insula is overgrown and by birth concealed by frontal, parietal, and temporal opercula. It includes gustatory and autonomic areas, but is less well understood than other cortical areas due to its hidden location.
Internal capsule
A compact, curved sheaf of thalamocortical, corticothalamic, and other cortical projection fibers shaped like part of a funnel. The internal capsule is divided into five regions, based on each region's relationship to the lenticular nucleus: 1)anterior limb = separates putamen from caudate nucleus 2) genu: knee-shaped bend in internal capsule 3) posterior limb
Optic radiation
A conspicuous, sharply defined, and heavily myelinated bundle of visual fibers originating in the lateral geniculate nucleus, departing the thalamus through the retrolenticular and sublenticular parts of the internal capsule, curving in a broad fan around the atrium and the posterior and inferior horns of the lateral ventricle, and terminating in the primary visual cortex on the upper and lower banks of the calcarine sulcus. See also Meyer's loop.
Stria of Gennari
Primary visual cortex (Brodmann's area 17), located in the banks of the calcarine sulcus. Named for the sheet of myelinated fibers (the stripe of Gennari) visible with the naked eye in layer IV.
Fornix
A prominent paired fiber bundle, mostly containing hippocampal efferents, that interconnects the hippocampus of each cerebral hemisphere and the ipsilateral septal area and hypothalamus.
Cerebral peduncle
As the term is used in this book, a massive sheaf of tightly packed corticospinal, corticobulbar, and corticopontine fibers traveling along the base of the midbrain = ANTERIORLY. (Others use the term „cerebral peduncle” to refer to all of one side of the midbrain inferior to the aqueduct. In this terminology, the bundle of corticofugal fibers is called the „pes pedunculi,” „basis pedunculi,” or „crus cerebri.”)
Red nucleus
POWER WALKING: A two-part nucleus in the rostral midbrain involved in cerebellar circuitry. In humans the large parvocellular part receives inputs from the contralateral dentate nucleus and provides a massive output of uncrossed fibers to the inferior olivary nucleus; the small magnocellular part receives inputs from the contralateral interposed nucleus and gives rise to a small, crossed rubrospinal tract.
central canal
The narrow, functionless vestige of the lumen of the spinal part of the embryonic neural tube, lined by ependyma and usually obstructed by epithelial debris. It runs the length of the spinal cord, contains traces of cerebrospinal fluid, and opens into the fourth ventricle at the obex of the medulla.
internal arcuate fibers
A general term for the large collection of axons that arch across the midline of the medulla. Many internal arcuate fibers are axons leaving the nuclei gracilis and cuneatus to form the contralateral medial lemniscus; most others are olivocerebellar fibers on their way to end as climbing fibers.
medial lemniscus (ribbon)
to thalamus directly; Somatosensory afferents originating from the contralateral posterior column nuclei and trigeminal main sensory nucleus and ascending through the brainstem to the thalamus (VPL/VPM). The medial lemniscus is the principal ascending pathway for tactile and proprioceptive information.
spinal trigeminal nucleus
The termination site of the spinal trigeminal tract. The caudal part of the nucleus (in the caudal medulla, merging with the cervical posterior horn) looks like the spinal posterior horn, has a component similar to the substantia gelatinosa, and processes pain and temperature information. Its efferents project to VPM through the spinothalamic tract. More rostral parts (the interpolar and oral nuclei) transmit trigeminal information to the cerebellum and into some trigeminal reflex arcs.
spinal trigeminal tract
Central processes of primary afferents from the ipsilateral side of the face, conveying information about pain and temperature (and some tactile information) to the spinal trigeminal nucleus.
inferiory olivary nucleus
A large nucleus in the anterolateral medulla, shaped like a bag with a convoluted wall of gray matter (like a crumpled, pitted olive). Olivary afferents are diverse (from the spinal cord, red nucleus, deep cerebellar nuclei, and other places), but efferents are all olivocerebellar. They pour out of its medially facing mouth (or hilus), cross the midline as internal arcuate fibers, join the inferior cerebellar peduncle, and blanket the contralateral cerebellum as climbing fibers that form powerful excitatory synapses on Purkinje cells and other neurons.
hypoglossal nucleus
A group of lower motor neurons that innervate muscles of the ipsilateral half of the tongue. Located in the floor of the fourth ventricle in the rostral medulla, near the midline.
solitary nucleus
The principal visceral sensory nucleus of the brainstem; the site of termination of the visceral primary afferents in the solitary tract. Located near the floor of the fourth ventricle in the rostral medulla and caudal pons, just lateral to the sulcus limitans and surrounding the solitary tract.
solitary tract
The principal visceral sensory nucleus of the brainstem; the site of termination of the visceral primary afferents in the solitary tract. Located near the floor of the fourth ventricle in the rostral medulla and caudal pons, just lateral to the sulcus limitans and surrounding the solitary tract.
inferior cerebellar peduncle
A major input route to the cerebellum, containing crossed olivocerebellar fibers that end as climbing fibers, the uncrossed posterior spinocerebellar and cuneocerebellar tracts, vestibulocerebellar fibers, and other cerebellar afferents. Sometimes referred to as the restiform („ropelike”) body.
middle cerebellar peduncle
The largest of the cerebellar peduncles, containing fibers from contralateral pontine nuclei that end as mossy fibers in almost all areas of cerebellar cortex. Sometimes referred to as the brachium pontis (the „arm of the pons”).
superior cerebellar peduncle
The major efferent route from the cerebellum, containing projections from deep cerebellar nuclei on their way to the contralateral red nucleus and thalamus (VL/VA). Sometimes referred to as the brachium conjunctivum (a „joined-together arm,” named for its course through a decussation with its contralateral counterpart). A descending limb leaves the superior cerebellar peduncle near its decussation and projects to the contralateral inferior olivary nucleus.
cochlear nuclei
The nuclei in which the primary auditory afferents of the vestibulocochlear nerve terminate. The dorsal and ventral cochlear nuclei form a continuous band of gray matter draped over the inferior cerebellar peduncle near the pontomedullary junction, and project bilaterally to the superior olivary nucleus and into the lateral lemniscus.
vestibular nuclear complex
Four elaborately subdivided secondary sensory nuclei of the vestibular division of the eighth cranial nerve in the floor of the fourth ventricle; collectively they project to the nuclei of extraocular muscles (mostly via the medial longitudinal fasciculus), the cerebellum, the reticular formation, the thalamus, and the spinal cord:
pontine nuclei
A collective term for the many small nuclei in the basal pons that receive afferents from cerebral cortex (via the internal capsule and cerebral peduncle) and project to contralateral cerebellar cortex (via the middle cerebellar peduncle).
abducens nucleus
The lower motor neurons for the ipsilateral lateral rectus, intermingled with interneurons that project through the contralateral medial longitudinal fasciculus (MLF) to medial rectus motor neurons; these interneurons provide for conjugate horizontal eye movements. Located near the midline, beneath the floor of the fourth ventricle in the caudal pons.
facial nerve
The seventh cranial nerve, which emerges anterolaterally from the brainstem along the groove between the basal pons and the medulla. The facial nerve serves nasopharyngeal, taste, and external ear sensation; controls muscles of facial expression; and regulates secretion by the submandibular, sublingual, and lacrimal glands.
facial nucleus
A group of lower motor neurons in the caudal pons that innervate muscles of the ipsilateral half of the face. Their axons loop over the abducens nucleus in the internal genu of the facial nerve.
trigeminal nerve
The fifth cranial nerve, emerging anterolaterally from the basal pons. The trigeminal nerve conveys somatosensory (and some chemosensory) fibers from the ipsilateral half of the head and efferents to ipsilateral muscles of mastication.
principal sensory nucleus of V
Termination site of large-diameter afferents (the equivalent of a posterior column nucleus for the trigeminal system). Most of its efferents project to the contralateral VPM via the medial lemniscus; some, however, project to the ipsilateral VPM via the dorsal trigeminal tract.
motor nucleus of V
Lower motor neurons for ipsilateral muscles of mastication.
lateral lemniscus
A flattened ribbon of fibers on the lateral surface of the rostral pontine tegmentum, arising from the cochlear nuclei and superior olivary nuclei. The lateral lemniscus is part of the ascending auditory pathway, conveying information from both ears to the inferior colliculus.
periaqueductal gray matter
An area of gray matter and poorly myelinated fibers surrounding the aqueduct in the midbrain. The periaqueductal gray is the site of origin of a descending pain-control pathway that relays in nucleus raphe magnus (among other connections).
trochlear nucleus
Lower motor neurons for the contralateral superior oblique muscle, located in the caudal midbrain just caudal to the oculomotor nucleus. Trochlear axons exit the paired nuclei, turn caudally in the overlying periaqueductal gray, arch posteriorly to decussate (like the old time ice-tongs used to handle large blocks of ice), and leave the brainstem at the pons-midbrain junction.
oculomotor complex
Lower motor neurons for the ipsilateral medial and inferior recti and inferior oblique, the contralateral superior rectus, and the levator palpebrae of both sides. Preganglionic parasympathetic neurons in one of its columns, the Edinger-Westphal nucleus, control the ipsilateral pupillary sphincter and ciliary muscle.
substantia nigra
dopamine: A large nucleus in the midbrain, interposed between the red nucleus and cerebral peduncle. The substantia nigra has two parts: a compact part, containing closely packed, pigmented (with neuromelanin) dopaminergic neurons that project to the striatum, and a reticular part, containing more loosely arranged neurons, receiving inputs from the striatum and projecting to the thalamus.
pretectum
The region between the superior colliculus and caudal thalamus. The pretectal area receives afferents from the retina and visual association cortex. It projects efferents bilaterally to the Edinger-Westphal nuclei, crossing both in the posterior commissure and in the ventral periaqueductal gray. It is a critical link in the pupillary light reflex.
cerebellar vermis
The most medial zone of the cerebellum, straddling the midline. Vermis is Latin for „worm.”
cerebellar hemispheres
The large paired lateral parts, important for motor planning and coordination of the limbs.
deep cerebellar nuclei
the fastigial, interposed, and dentate nuclei