Spinal Nerve


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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

References in periodicals archive ?
Light Microscopic Findings: In the control group, the spinal nerve roots were observed at different diameters.
Kuntz described the lateral branches as the GRC to the sixth and seventh cervical spinal nerves. Laubmann described VG as arising from the lower part of the 6th cervical sympathetic ganglion and the GRC from VG to be connected to the 6th cervical spinal nerve.
These can grow inside joint capsules or in the intervertebral foramen, placing pressure on the existing nerve roots and emerging spinal nerves which could manifest as shooting pain, tingling, pins and needles, numbness, and specific muscle weakness.
We present our surgical experience with five such tumors, one arising from the maxillary branch of the trigeminal nerve in the maxillary sinus, second arising from the brachial plexus, third arising from the cervical vagus, and two arising from cervical spinal nerves. The clinical presentation, surgical treatment, and outcomes of patients with this pathology are described.
In the last twenty years, all patients with clinical indications of spinal nerve root deficits were evaluated with neurophysiologic studies.
Nerve branches disperse from cervicothoracic ganglion to ventral rami of the eighth cervical (C8), the first (T1) and second (T2) thoracal spinal nerves or to brachial plexus (Dursun, 2000; Pather et al., 2006; Ozgel et al., 2009; Song et al., 2010).
In males, the femoral nerve originated from the ventral branches of the fourth, sixth and seventh lumbar spinal nerves in seven animals (46.67%), from the ventral branches of the fifth and sixth lumbar spinal nerves in two animals (13.33%), from the ventral branch of the fifth lumbar spinal nerve in one animal (6.67%), from the ventral branches of the fifth, sixth and seventh lumbar spinal nerves in three animals (20.00%), from the ventral branches of the fourth and fifth lumbar spinal nerves in one animal (6.67%), and from the ventral branches of the fifth and seventh lumbar spinal nerves in one animal (6.67%).
Objective: To compare the clinical therapeutic effects of anterior decompression and posterior decompression on thoracolumbar spine fracture (TSF) complicated with spinal nerve injury (SNI).
Although perineural tumor spread in the head and neck most commonly involves the cranial nerves, particularly the trigeminal and facial nerves, the spinal nerve branches can also be affected.
Clinical and radiologic examinations, including radiography, computed tomography scan, and myelography, were indicative of neoplasia involving a spinal nerve root.
Diagnosis: Adult-onset scoliosis, an asymmetrical curvature of the spine that, if unchecked, could eventually leave me even shorter and more crooked, disabled by an entrapped spinal nerve, and dependent on a walker to maintain my balance.
If we do a quick search of the anatomy, we see that out of the neck vertebrae, the spinal nerve roots exit the spine and go to innervate the shoulders arms and hands, from the upper cervical spine the nerve roots go to the head, ears, eyes, nose sinus, and mucous membranes of the throat.

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