selkäydinhermo

Selkäydinhermo, also known as a spinal nerve, is a mixed nerve that carries motor, sensory, and autonomic information between the spinal cord and the rest of the body. There are 31 pairs of spinal nerves in humans, categorized by their location in the vertebral column: 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve. Each spinal nerve originates from the spinal cord by two roots: a dorsal root, which is sensory, and a ventral root, which is motor. These roots merge to form the spinal nerve.

The dorsal root ganglion, located on the dorsal root, contains the cell bodies of sensory neurons. Once the dorsal and ventral roots combine, the spinal nerve divides into several branches, including the dorsal ramus, which innervates the muscles and skin of the back, and the ventral ramus, which forms the nerve plexuses that supply the limbs and the anterior and lateral trunk. The autonomic nervous system is also influenced by spinal nerves, particularly through sympathetic fibers originating from the thoracic and upper lumbar segments. These nerves play a crucial role in coordinating bodily functions and responding to stimuli.