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Anatomy Atlases: Atlas of Microscopic Anatomy: Appendix V: Nervous System Glossary of Terms Atlas of Microscopic Anatomy

Appendix V: Nervous System Glossary of Terms

Ronald A. Bergman, Ph.D., Adel K. Afifi, M.D., Paul M. Heidger, Jr., Ph.D.
Peer Review Status: Externally Peer Reviewed

Abducens: L. abducere, to move away. The abducens nerve supplies the lateral rectus muscle, which draws the pupil of the eye away from the midline.

Amygdala: L. from Gr. amygdalO, almond. An almond-shaped structure in the tip of the temporal lobe.

Ansa: L. loop, handle (of a jug). Ansa lenticularis loops around the internal capsule on its way from globus palliclus to thalamus.

Aqueduct: L. aqueductus, a conduit or canal. Cerebral aqueduct connects the fourth and third ventricles.

Arcuate: L. arcuatus, bowed. Arcuate nucleus of medulla oblongata. Internal arcuate fibers of medulla oblongata.

Brachium: L. from Gr. brachion, arm. Brachium conjunctivurn, brachium of inferior colliculus, brachium of superior colliculus.

Callosum: L. hard. Corpus callosum, a massive bundle of myelinated fibers connecting the two cerebral hemispheres. Galen described the corpus callosurn as a firm, tough body.

Caudate: L. tailed, having a tail. Cauclate nucleus has a head, body, and slender tail.

Centrum: L. from Gr. kentron, a center. Centrum semiovale, the mass of white matter composing the interior of the cerebral hemisphere. Has a sernioval shape in horizontal sections.

Cerebellar: Pertaining to cerebellum.

Cerebellum: L. diminutive of cerebrum, the brain. The cerebellum is thus the little brain. The term appeared in English in 1565.

Cerebrum: L. brain. The word first appeared in English in 1565.

Chiasma: Gr. chiasma, two crossing lines. Optic chiasma is the site of crossing of optic nerve fibers to form the optic tract.

Choroid: Gr. choroeid6s, a delicate membrane. Choroid plexus within the brain ventricles was first described by Herophilus (~300 BC).

Cingulate: Pertaining to cingulum. Cingulate gyrus of the limbic lobe.

Cingulum: L. a girdle, from cingere, to bind or gird. The white matter core of the cingulate gyrus surrounds the corpus callosurn like a girdle.

Claustrum: L. a barrier or fence, from claudere, to shut or close. A thin layer of gray matter between the cortex of the insula (island of Reil) and the putamen. The claustrum was described by Meynert (1833 -1892).

Cochlea: L. snail shell. The receptor organ of hearing is so-named because of its striking resemblance, with its two and a half turns, to a snail shell.

Cochlear: Pertaining to cochlea.

Colliculus: L. diminutive of collis, hill. A small elevation. Superior and inferior colliculi are elevations on the dorsal surface of the mid-brain.

Column: L. columna, a pillar, a vertical object. Posterior (dorsal) columns of the spinal cord are disposed in a vertical manner.

Commissure: L. a joining together, from corn-mitto, to bring together. The anterior, posterior, and habenular commissures join two sides of the nervous system.

Corona: L. from Gr. koróné, a crown. Corona radiata, fibers radiating out like a crown from the internal capsule to various parts of the cerebral hemispheres. The corona radiata was described and named by Reil (1759-1813).

Corpus: L. body. The corpus callosurn Is a massive bundle (body) of myelinated nerve fibers connecting the two cerebral hemispheres. The term corpus callosurn is a translation of Galen's term (callosus, hard), who noted the structure and called it the firm, tough body.

Crus: L. leg. The crus of the fornix. Crus cerebri.

Cuneatus: L. cuneus, wedge. Wedge-shaped. Nucleus and tractus cuneatus.

Decussation: L. decussatio, from decussis, the intersection of two lines, the letter x. Crossing of tracts, motor clecussation, sensory clecussation.

Dentate: L. dentatus, toothed. Dentate nucleus of cerebellum; dentate gyrus of hippocampal formation.

Diencephalon: Gr. dia, through, between; enkephalos, brain. The between brain.

Fasciculus: L. fascis, bundle. Fiber bundle or tract. Fasciculus gracilis, fasciculus cuneatus, medial longitudinal fasciculus.

Fimbria: L. firnbria, fringe or border. Fimbria of fornix.

Folia: plural of folium, L. leaf. A leaf-like structure. Cerebellar folia.

Forceps: L. a pair of tongs. U-shaped, or pincer-like appearance of forceps major and forceps minor of the corpus callosum.

Fornix: L. arch. The forn'x is an arched structure connecting the hippocampus with the mamillary body. First described by Vesalius (1514-1564).

Funiculus: L. funis, cord. A cord-like area of white matter containing several neural tracts. Anterior and lateral funiculi of spinal cord.

Geniculate: L. geniculo, to bend the knee, from genu, knee. Lateral and medial geniculate nuclei.

Genu: L. genu, knee. Genu of the corpus callosurn betwee-n its body and head. Genu of internal capsule between the anterior and posterior limbs. Genu of facial nerve in the pons.

Globus: L. globe, sphere, round body, a ball. Globus pallidus, the pale globe. Globose nucleus of cerebellum.

Glossopharyngeal: Gr. glossa, tongue; pharynx, throat. Relating to tongue and throat. Glossopharyngeal nerve.

Gracilis: L. slender. Fasciculus gracilis, a long and slender fiber tract in the spinal cord.

Gyrus: L. from Gr. gyros, circle. Cerebral gyri.

Habenula: L. habena, strap or bridle rein; from habere, to hold. Habenular nuclei, so-named because early anatomists considered the pineal gland the seat of the soul, and the adjacent habenulae were the reins by which the soul controlled the brain.

Hippocampus: Gr. hippocampos, sea horse. The hippocampus is so-named because of its resemblance to a sea horse.

Hypoglossal: L. hypoglossus; from hypo, under, glossus, tongue. The hypoglossal nerve was so-named by the Danish anatomist Winslow (1669-1760).

Innominate: L. innominatus, unnamed, nameless; from in, not, nornen, name. Substantia innominata.

insula: L. island. The insula or island of Reii in the depth of the lateral (sylvian) fissure. Previously noted by other writers, it was described by Johann Christian Reil in 1809.

Lemniscus: Gr. li~mniskos, ribbon, fillet. Medial lemniscus, lateral lemniscus.

Lenticular: L. lenticula, a lentil. Relating or resembling a lens. Lenticular nucleus (putamen and globus pallidus) is so-named because of its resemblance to a lens.

Mamillary: L. mammilla, nipple. Shaped like a nipple. Mamillary bodies are nipple-like elevations from the surface of the diencephalon.

Medulla: L. medius, middle. The middle or marrow of bone. Medulla oblongata.

Mesencephalon: Gr. mesos, middle, enkephalos, brain. The mid-brain between the pons and thalamus.

Occipital: Relating to occiput.

Occiput: L. the back of the head; from ob, before or against, caput, head.

Oculomotor: L. oculomotorius; from oculus, eye, motorius, moving. Related to or causing movement of the eye. Oculomotor nerve.

Olivary: Pertaining to olive.

Olive: L. oliva, olive. The inferior olive is a smooth oval prominence on the surface of the medulla oblongata.

Optic: Gr. optikos, relating to the eye, sight. Optic nerve is the nerve of vision. Discovered by Alcmaeon about 500 B.C.

Pallidus: L. pallidus, pale. Globus pallidus, the pale gray portion of the corpus striatum.

Peduncle: L. pedunculus, diminutive of pes, foot. A stem or narrow part by which some part is attached to another. Cerebral peduncle, inferior, middle, and superior cerebellar peduncles connect different parts of the neuraxis.

Pellucidum: L. pellucidus, allowing the passage of light, transparent. Septum pellucidum is a thin membrane extending between the corpus callosurn and fornix. It separates the frontal horns of the lateral ventricle. First described by Galen (130-201 A.D.)

Pineal: L. pineus, relating to pine. Pineal gland resembles a pine cone. First described by Berengarius about 1500. Descartes (1596-1650) declared it the residence of the soul.

Pons: L. bridge. The pons is the part of the brain stem intermediate between the medulla oblongata and mid-brain. Also known as pons varolii. Described by Varolius of Padua in 1573.

Pulvinar: L, pulvinus, a cushion. The posterior extremity of the thalamus slung over the posterior aspect of the internal capsule like a cushion.

Putamen: from L. puto, to prune. That which falls off in pruning.

Pyramid: Gr. pyramis, a pyramid. The pyramidal tract was so-named by Duverney from the pyramids, two eminences on the medulla oblongata formed by the corticospinal tracts.

Radiata: L. radius, ray, atus, to shine. Corona radiata spreads out in all directions from the internal capsule like the rays of light.

Rectus: L. rectus, straight. Cyrus rectus.

Restiform: L. restis, rope, forma, shape. Shaped like a rope. Restiform body is a compact bundle of nerve fibers connecting the medulla and the cerebellum. Described and named by Humphrey Ridley, an English anatomist, in 1695.

Rostrum: L. beak, or bill of a bird. The rostrum . a furrow or groove. Stria medullaris thalami.

Substantia: L. substantia, essence, substance, material. Substantia gelatinosa of Rolandi was first described by Luigi Rolando (1773 -1831), an Italian anatomist, as a formation of a peculiar transparent substance at the tip of the posterior horn of the spinal cord. Substantia nigra is a pigmented area in the mid-brain described by Soemmering (1755 -1830).

Sulcus: L. a furrow or ditch. Suld of the brain are furrows between the gyri.

Tectal: Pertaining to tectum.

Tectum: L. roof, from tego, to cover. The tectum of the mid-brain refers to the dorsal parts of the mid- brain, the superior and inferior colliculi.

Tegmental: Pertaining to tegmentum.

Tegmentum: L. tego, cover. Tegmentum of the brain stem.

Thalamus: Gr. thalamos, inner chamber, bridal chamber. The term was used by Galen.

Trapezoid: Gr. trapezodes, from trapezoin, a table or counter, eidos, resemblance. Resembling a trapezium. The trapezoid body of the pons.

Trigeminal: L. trigerninus, three-fold. Trigeminal nerve has three divisions. It was described by Fallopius and again by Meckel in 1748. The name trigerninal was given by Winslow on account of its three divisions.

Trochlea: Gr. trochileia, a pulley. Trochlear nerve supplies the superior extraocular oblique muscle, whose tendon passes through a fibrous ring, the trochlea.

Trochlear: Relating to trochlea.

Velum: L. veil. Anterior medullary velum.

Ventricle: L. ventriculus, from venter, belly, chamber, cavity. Ventricles of the brain were so-named because it was at one time fashionable to name parts of the brain for other parts of the body that they resembled.

Vermis: L. worm. Vermis of cerebellum, so-named because of its worm-like appearance.

Vestibular: Related to vestibule. Vestibular nuclei.

Vestibule: L. vestibulum, antechamber, entrance court.

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