Spinal nerve

From ArticleWorld

Spinal nerve refers to the mixed spinal nerve, formed from two roots emerging from the spinal cord. The part that goes from the vertebrae through the intervertebral foramen is the spinal nerve.

The spinal nerves

There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and one coccygeal spinal nerve. The first seven cervical spinal nerves emerge from the vertebral canal above each respective cervical vertebra, and all other nerves emerge from below their respective vertebra.

How the spinal nerves are formed

A pair of roots emerge from the dorsal and, respectively, ventral part of the spinal cord, out of the gray matter. Afferent sensory axons are contained in the dorsal root, and efferent sensory axons in the ventral root. Each of these roots continue out of the spinal column, forming root ganglia, and, subsequently, a mixed spinal nerve.

Subsequently, the nerve splits into two primary branches, that further branch to form a number of other sub-nerves. The ventral rami has two branches that lead to a sympathetic ganglion. These ganglia form the sympathetic chain by connecting to the other ganglia above them.

Functions

The spinal nerve is a very important nerve of the nervous system. This nerve receives sensations from dermatomes and controls muscle contractions. Any loss of tactile sensation or muscle weakness may be a sign of nerved being adversely affected.

Any condition that affects the spinal nerves is serious should be treated as a medical emergency.