| ventral primary ramus of spinal nerve | <anatomy, nerve> The larger, anterolaterally-directed major terminal branch (with the dorsal primary ramus) of all 31 pairs of mixed spinal nerves, formed at the intervertebral foramen. Most ventral primary rami, especially those involved in the innervation of the limbs, participate in the formation of the major nerve plexuses (cervical, brachial, and lumbosacral) and lose their identities. Most in the thoracic region, however, remain separate from adjacent rami to become the intercostal and subcostal nerves. Ventral primary rami provide innervation to the anterolateral body wall and trunk. Nomina Anatomica lists ventral primary rami as "rami ventrales" for each group of spinal nerves: 1) cervical (nervorum cervicalium ), 2) thoracic (nervorum thoracicorum ), 3) lumbar (nervorum lumbalium ), 4) sacral (nervorum sacralium )m, and 5) coccygeal (nervi coccygei ). Synonym: ramus ventralis nervi spinalis, anterior primary division. (05 Mar 2000) |
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| ventral root | The motor root of a spinal nerve. Synonym: radix anterior, radix motoria, anterior root, motor root, radix ventralis. (05 Mar 2000) |
| ventral sacrococcygeal ligament | <anatomy> The continuation of the anterior longitudinal ligament uniting the sacrum and coccyx. Synonym: ligamentum sacrococcygeum anterius, anterior sacrococcygeal ligament. (05 Mar 2000) |
| ventral sacrococcygeal muscle | <anatomy> An inconstant muscle on the pelvic surfaces of the sacrum and coccyx, the remains of a portion of the tail musculature of lower animals. Synonym: musculus sacrococcygeus ventralis, musculus sacrococcygeus anterior, ventral sacrococcygeal muscle. (05 Mar 2000) |
| ventral sacrococcygeus muscle | <anatomy> An inconstant muscle on the pelvic surfaces of the sacrum and coccyx, the remains of a portion of the tail musculature of lower animals. Synonym: musculus sacrococcygeus ventralis, musculus sacrococcygeus anterior, ventral sacrococcygeal muscle. (05 Mar 2000) |
| ventral sacroiliac ligaments | The strong fibrous bands that reinforce the sacroiliac joint anteriorly. Synonym: ligamenta sacroiliaca anteriora, ventral sacroiliac ligaments. (05 Mar 2000) |
| ventral spinocerebellar tract | A bundle of fibres originating in the base of the posterior horn and zona intermedia throughout lumbosacral segments of the spinal cord, crossing to the opposite side and ascending in a peripheral position in the ventral half of the lateral funiculus. In its ascent through the rhombencephalon, the tract curves sharply dorsalward along the rostral border of the trigeminal motor nucleus, entering the cerebellum in a caudal direction over the dorsal surface of the superior cerebellar peduncle, and terminating as mossy fibres in the granular layer of the cortex of the cerebellar vermis. The bundle conveys proprioceptive and exteroceptive information largely from the opposite lower extremity. Synonym: tractus spinocerebellaris anterior, Gowers' column, Gowers' tract, ventral spinocerebellar tract. (05 Mar 2000) |
| ventral spinothalamic tract | The more anterior or ventral part of the spinothalamic tract that is involved in tactile sensation. See: spinothalamic tract. Synonym: tractus spinothalamicus anterior, ventral spinothalamic tract. (05 Mar 2000) |
| ventral splanchnic arteries | Artery's that arise on the embryo from the dorsal aorta and are distributed to the digestive tube. (05 Mar 2000) |
| ventral tegmental area | A region in the mesencephalon which is dorsomedial to the substantia nigra and ventral to the red nucleus. The mesocortical and mesolimbic dopaminergic systems originate here, including an important projection to the nucleus accumbens. Overactivity of the cells in this area has been suspected to contribute to the positive symptoms of schizophrenia. (12 Dec 1998) |
| ventral tegmental decussation | See: tegmental decussations. (05 Mar 2000) |
| ventral thalamic peduncle | The massive system of fibre bundles emerging through the ventral, lateral, and anterior borders of the thalamus to join the internal capsule and parts of the corona radiata; it contains the fibres reciprocally connecting the ventral thalamic nuclei with the precentral and postcentral gyri of the cerebral cortex. Synonym: pedunculus thalami ventralis. (05 Mar 2000) |
| ventral tier thalamic nuclei | Collective term for nuclei in the ventral part of the lateral nuclear group, e.g., ventral anterior, lateral, posterolateral, and posteromedial nuclei and the medial and lateral geniculate bodies. The basoventral nuclear complex constitutes the caudal part of the ventral tier thalamic nuclei. (05 Mar 2000) |
| ventral white column | A narrow band of white substance bordering on the anterior median fissure of the spinal cord in front of the anterior gray commissure, and consisting of nerve fibres crossing over from one half of the spinal cord to the other. Synonym: commissura alba, anterior white commissure, commissura ventralis alba, ventral white column. (05 Mar 2000) |
| lateral cutaneous branches of ventral primary ramus of thoracic spinal nerves | Branches arising in approximately the anterior axillary line at the level of the second through sixth intercostal spaces. Synonym: rami mammarii laterales nervorum intercostalium, lateral cutaneous branches of intercostal nerves. (05 Mar 2000) |