Spinal nerves are the major nerves of the body. A total of 31 pairs of spinal nerves control motor, sensory, and other functions. These nerves are located at the cervical, thoracic, lumbar, sacral, and coccygeal levels.
Motor messages to the spinal nerves originate in the brain. The motor strip (homunculus) in the brain initiates a command for muscle control. This command is sent to the spine through nerve impulses and then travels through the motor root to the spinal nerve.
These are muscle movement, sensation, and autonomic functions (control of internal organs). Because their function is so well understood, when a particular spinal nerve becomes impaired, the resulting deficit often pinpoints which spinal nerve or nerves are affected. Motor messages to the spinal nerves originate in the brain.