| 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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| recurrent meningeal branch of spinal nerves | A branch from the initial (mixed) part of each spinal nerve passing in a recurrent fashion back through the intervertebral foramen to supply spinal meninges, the posterior longitudinal ligament, posterolateral periphery of the intervertebral disc, and periosteum of the vertebrae. Synonym: ramus meningeus nervorum spinalium, recurrent meningeal branch of spinal nerves, sinuvertebral nerves. (05 Mar 2000) |
| glioma of the spinal cord | A glial tumour of the spinal cord, commonly an ependymoma; neoplasms of the spinal cord are relatively rare, but glioma's constitute approximately one-fourth of the total. (05 Mar 2000) |
| central canal of spinal cord | The ependyma-lined lumen (cavity) of the neural tube, the cerebral part of which remains patent to form the ventricles of the brain, while the spinal part in the adult often is reduced to a solid strand of modified ependyma. Synonym: canalis centralis medullae spinalis, central canal of spinal cord, tubus medullaris. Synonym: syringocele. (05 Mar 2000) |
| medullary spinal arteries | A large caliber spinal or radicular artery which courses centrally along a dorsal or ventral root, perhaps supplying it and the surrounding meninges in the fashion of any spinal/radicular artery, but which continues on to reach and anastomose with the anterior or posterior (longitudinal) spinal artery. Only 4-9 of the spinal arteries are medullary spinal arteries, found mainly in the lower cervical, lower thoracic and upper lumbar levels, the largest of which is the great radicular artery. (05 Mar 2000) |
| cervical enlargement of spinal cord | A spindle-shaped swelling of the spinal cord extending from the third cervical to the second thoracic vertebra, with maximum thickness opposite the fifth or sixth cervical vertebra, consequential to the innervation of the upper limb. Synonym: intumescentia cervicalis, cervical enlargement of spinal cord. (05 Mar 2000) |
| cervical part of spinal cord | The part of the spinal cord that consists of the eight cervical segments and gives rise to the first eight pairs of spinal nerves. Synonym: pars cervicalis medullae spinalis. (05 Mar 2000) |
| cervical segments of spinal cord | The eight cervical segments [C1-C8] of the spinal cord which give rise to the eight pairs of cervical spinal nerves and constitute the cervical part of the spinal cord. Synonym: segmenta medullae spinalis cervicalia. (05 Mar 2000) |
| meningeal branch of spinal nerves | A branch from the initial (mixed) part of each spinal nerve passing in a recurrent fashion back through the intervertebral foramen to supply spinal meninges, the posterior longitudinal ligament, posterolateral periphery of the intervertebral disc, and periosteum of the vertebrae. Synonym: ramus meningeus nervorum spinalium, recurrent meningeal branch of spinal nerves, sinuvertebral nerves. (05 Mar 2000) |
| groove for spinal nerve | <anatomy, nerve> The laterally directed groove on the superior surface of the transverse processes of typical cervical vertebrae between the anterior and posterior tubercles along which the emerging spinal nerve passes. Synonym: sulcus nervi spinalis. (05 Mar 2000) |
| coccygeal part of spinal cord | The terminal part of the spinal cord consisting of the three coccygeal segments of the spinal cord from which the three pairs of coccygeal nerves originate. Synonym: pars coccygea medullae spinalis, segmenta medullae spinalis coccygea. (05 Mar 2000) |
| coccygeal segments of spinal cord | The three coccygeal segments [Co1-Co3] of the spinal cord which give rise to the three pairs of coccygeal spinal nerves and constitute the coccygeal part of the spinal cord. (05 Mar 2000) |
| communicating branches of spinal nerves | Short nerves arising from the initial portion of the ventral primary rami of the thoracic and upper lumbar spinal nerves through which all presynaptic sympathetic nerve fibres must pass to reach the sympathetic trunks; also conveyed by the white rami communicans are visceral afferent (sensory) fibres which were conveyed to the sympathetic trunks in splanchnic nerves. Most fibres conveyed by the white rami communicantes are myelinated. Synonym: rami communicantes nervorum spinalium, communicating branches of spinal nerves. (05 Mar 2000) |
| communicating rami of spinal nerves | The communicating branches of spinal nerves, small bundles of nerve fibres connecting spinal nerves with sympathetic ganglia; the fibres passing from the ganglion to the spinal nerve are nonmyelinated and are called gray rami communicantes, those passing in the reverse direction are myelinated and are called white rami communicantes. (05 Mar 2000) |
| plexus of spinal nerves | An intermingling of fibre fascicles from adjacent spinal nerves to form a network; the major plexus's are the cervical, brachial, and lumbosacral. Synonym: plexus nervorum spinalium. (05 Mar 2000) |