Nerve root

A nerve root is the initial segment of a nerve leaving the central nervous system. Types include:

• A cranial nerve root, the beginning of one of the twelve pairs leaving the central nervous system from the brain stem or the highest levels of the spinal cord;
• A spinal nerve root, the beginning of one of the thirty-one pairs leaving the central nervous system from the spinal cord. Each spinal nerve root consists of the union of a sensory dorsal root and a motor ventral root.