The spinal nerve roots run through the bony canal of the spinal cord, and one pair of roots exits at each level of the spine. The spinal roots exit from both the dorsal and ventral sides of the spine, states Spine-Health.com.
The spinal cord is a cylindrical structure that runs continuously from the base of the brain to the lumbar section of the back, a total distance of 40 to 50 centimeters, states Neuroscience Online. It is composed of white and gray matter that carries sensory information from the brain to other parts of the body and back again. Injuries to the spinal cord can cause temporary or permanent changes in body functions below the site of the injury, states Mayo Clinic.