Spinalnerverna

Spinalnerverna are a set of paired mixed nerves that emerge from the spinal cord and exit the vertebral column through the intervertebral foramina. In humans, there are 31 pairs: eight cervical (C1–C8), twelve thoracic (T1–T12), five lumbar (L1–L5), five sacral (S1–S5), and one coccygeal (Co1). Each spinal nerve is formed by the union of a dorsal root, which carries sensory fibers, and a ventral root, which carries motor fibers, producing a mixed nerve that then divides into branches.

Dorsal (posterior) rami innervate the intrinsic back muscles and the overlying skin, while ventral (anterior) rami supply the majority of the trunk’s and limbs’ muscles and skin. In the thoracic and upper lumbar regions, connecting branches called the white and gray rami communicantes link certain ventral rami to the sympathetic nervous system, contributing to autonomic innervation.

The dorsal root contains the cell bodies of sensory neurons located in the dorsal root ganglion. After formation, the spinal nerve typically splits into a dorsal ramus and a ventral ramus, though some fibers may form regional networks such as nerve plexuses in the cervical, brachial, lumbar, and sacral regions, from which named nerves originate.

Clinical relevance includes injury or compression of spinal nerves, such as radiculopathy from disc herniation or spinal stenosis, which can cause pain, weakness, or sensory disturbances in the corresponding dermatome and myotome. Understanding spinal nerve organization informs diagnostic approaches and regional anesthesia techniques.