spinal nerve

n. Any of the 62 paired nerves emerging from the spinal cord, each attached to the cord by two roots, anterior or ventral and posterior or dorsal, the latter provided with a spinal ganglion.

spi′nal nerve′

n. any of a series of paired nerves that originate in the nerve roots of the spinal cord and emerge from the vertebrae on both sides of the spinal column, each branching out to innervate a specific region of the neck, trunk, or limbs. [1785–95]

Thesaurus

Noun

spinal nerve - any of the 31 pairs of nerves emerging from each side of the spinal cord (each attached to the cord by two roots: ventral and dorsal)nervus spinalisdorsal horn, dorsal root - one of the two roots of a spinal nerve that passes dorsally to the spinal cord and that consists of sensory fibersanterior horn, anterior root, ventral horn, ventral root - one of two the two roots of a spinal nerve that passes ventrally from the spinal cord and that consists of motor fibersnerve, nervus - any bundle of nerve fibers running to various organs and tissues of the bodyanterior crural nerve, femoral nerve, nervus femoralis - one of a pair of nerves that originate from lumbar nerves and supply the muscles and skin of the anterior part of the thighnervus phrenicus, phrenic nerve - one of a pair of nerves that arises from cervical spinal roots and passes down the thorax to innervate the diaphragm and control breathingcervical nerve - any of eight pairs of spinal nerves emerging from the cervical section of the spinal cordcoccygeal nerve, nervus coccygeus - the lowest pair of spinal nerveslumbar nerve - any of five pairs of spinal nerves emerging from the lumbar section of the spinal cordsacral nerve - any of five pairs of spinal nerves emerging from the sacral region of the spinal cordthoracic nerve - any of twelve pairs of spinal nerves emerging from the thoracic region of the spinal cord

Spinal Nerve

spinal nerve

[′spīn·əl ¦nərv] (neuroscience) Any of the paired nerves arising from the spinal cord.

Spinal Nerve

a short (approximately 2 cm long) strand of nerve fibers formed segmentally as a result of the fusion of the dorsal (sensory) and ventral (motor) roots of the spinal cord.

Humans have 31 pairs of spinal nerves. Each pair corresponds to a segment of the spinal cord, with eight pairs of cervical nerves, 12 pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. Sensory fibers are the processes of the cells of spinal ganglia, and motor fibers are the processes of motoneurons situated in the anterior horns of the gray substance of the spinal cord. Reaching the spinal nerves along with the motor neurons are efferent autonomic branches, which are the processes of nerve cells found in the lateral horns. Myelinated nerve fibers are most numerous in spinal nerves at the cervical spinal swelling (as many as 44,000 fibers in a nerve) and the lumbar spinal swelling (over 55,000 fibers in a nerve).

Spinal nerves emerge through corresponding intervertebral foramina symmetrically on both sides of the spine and are divided into four branches. Departing reversely from each spinal nerve is a delicate meningeal branch that participates in the innervation of the meninges of the spinal cord. The spinal nerves then divide into anterior and posterior somatic branches, which innervate the skin of the trunk and extremities and all body muscles except those of the head. Autonomic sympathetic conductors, called white communicating branches, separate from the spinal nerves or from the anterior branch of spinal nerves and proceed to the ganglia of the sympathetic trunk of the sympathetic nervous system.

The anterior branches of the four upper cervical spinal nerves form the cervical plexus, the last four cervical and the first and second thoracic spinal nerves form the brachial plexus, the twelfth thoracic and the four upper lumbar spinal nerves form the lumbar plexus, the fifth lumbar and the first three sacral spinal nerves form the sacral plexus, and the fourth and fifth sacral and the coccygeal spinal nerves form the coccygeal plexus.

The spinal nerves and the plexuses they form innervate the skin and skeletal muscles.

For injuries to the spinal nerves, seeRADICULITIS; for injuries to the plexuses, seePLEXITIS.

REFERENCES

Mnogotomnoe rukovodstvo po nevrologii, vol. 1, book 1. Moscow, 1955.

V. V. KUPRIIANOV and V. B. GEL’FAND

spinal nerve

n. Any of the 62 paired nerves emerging from the spinal cord, each attached to the cord by two roots, anterior or ventral and posterior or dorsal, the latter provided with a spinal ganglion.

spinal nerve

Anatomy Any one of the 31 pairs of nerves that arise from the spinal cord

SPINAL NERVES: Left side

SPINAL NERVES

spinal nerve

Any of the 31 sets of nerves originating in the spinal cord and emerging from the spinal canal through intervertebral foramina. Each spinal nerve is the concatenation of two sets of axons that emerge separately from the spinal cord: sensory axons (the dorsal root) and motor axons (the ventral root). See: illustrationillustrationSee also: nerve

spinal nerve

any of numerous nerves which leave the SPINAL CORD, one pair in each segment, each being connected with the cord by a dorsal and a ventral root. They are ‘mixed nerves’ (containing both sensory and motor fibres) and carry groups of AXONS to receptors and effectors in different parts of the body see REFLEX ARC.

spinal nerve

noun

Synonyms for spinal nerve

noun any of the 31 pairs of nerves emerging from each side of the spinal cord (each attached to the cord by two roots: ventral and dorsal)

Synonyms

nervus spinalis

Related Words

dorsal horn
dorsal root
anterior horn
anterior root
ventral horn
ventral root
nerve
nervus
anterior crural nerve
femoral nerve
nervus femoralis
nervus phrenicus
phrenic nerve
cervical nerve
coccygeal nerve
nervus coccygeus
lumbar nerve
sacral nerve
thoracic nerve