Spinalnervs

Spinalnervs refer to the paired mixed nerves that emerge from the spinal cord, forming part of the peripheral nervous system. Each spinalnerv is formed by the dorsal root, which carries sensory information to the spinal cord and contains a dorsal root ganglion, and the ventral root, which transmits motor signals from the spinal cord to skeletal muscles. The two roots join to form a single mixed spinal nerve shortly after exiting the spinal column.

In humans there are 31 pairs of spinalnervs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. After leaving the intervertebral foramen, each spinalnerv typically divides into a dorsal ramus and a ventral ramus. The dorsal ramus supplies the muscles and skin of the back, while the ventral ramus supplies the trunk and limbs. In the thoracic region, the ventral rami become intercostal nerves; in other regions they contribute to the formation of major nerve plexuses (cervical, brachial, and lumbosacral).

Functionally, spinalnervs carry somatic sensory information from the skin, muscles, and joints and provide motor commands to skeletal muscles. They may also transmit autonomic fibers that participate in regulating visceral functions, primarily through interactions with nearby sympathetic pathways.

Clinical relevance includes radiculopathy from nerve compression or inflammation, such as might occur with herniated discs or foraminal stenosis, producing pain, weakness, and sensory loss in a dermatomal distribution. Severe compression of multiple roots, as in cauda equina syndrome, requires urgent evaluation.

Developmentally, spinalnervs arise from the neural tube and neural crest during embryogenesis. The dorsal root ganglia derive from neural crest cells; central processes enter the spinal cord while peripheral processes extend to peripheral targets.