noun, plural: spinal nerves
The spinal nerve is a nerve that occurs in pairs emerging from the spinal cord. Each pair is attached to the cord by two roots, i.e. the anterior (ventral) and posterior (dorsal) roots. The latter is provided with a spinal ganglion. Although these two roots unite in the intervertebral foramen they divide again into anterior division (or ventral ramus) and posterior division (or dorsal ramus). The anterior division is the one that supplies the foreparts of the body and the limbs whereas the posterior division supplies the muscles and the skin of the back.1
In humans, there are 31 pairs of spinal nerves emerging from the spinal cord and are grouped based on the corresponding regions of the spine from where they emerge, i.e. cervical, thoracic, lumbar, sacral, and coccygeal spinal nerves. In particular, there are 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.
The spinal nerves are part of the peripheral nervous system.
1 spinal nerve. (n.d.). The American Heritage® Science Dictionary. Retrieved from Dictionary.com website http://www.dictionary.com/browse/spinal-nerve