noun
: any of the paired nerves that leave the spinal cord of a craniate vertebrate by way of the intervertebral foramina, supply muscles of the trunk and limbs, and connect with the nerves of the sympathetic system, that arise by a short motor ventral root and a short sensory dorsal root which bears a spinal ganglion close to the cord and unites with the ventral root just beyond the ganglion forming a nerve of mixed function which passes through the foramen and divides into two mixed nerves of which one supplies dorsal and the other ventral bodily structures, and that normally aggregate 31 pairs in man and are divided according to the part of the cord from which they arise into 8 cervical pairs, 12 thoracic pairs, 5 lumbar pairs, 5 sacral pairs, and one coccygeal pair