Spinal Cord and Nerve Roots
The spinal cord is the portion of the central nervous system that extends from the base of the brain to about two-thirds of the way down the back. It runs through a cavity called the vertebral canal. The spinal cord consists of nerve cells and bundles of nerves that send signals to the brain. Because of its delicate nature and its importance to the body, the spinal cord is a heavily defended area. Three layers of protective structures encompass the spinal cord like tubing. These protective membranes are referred to as meninges and are individually called the dura, the arachnoid and the pia mater. Additionally, cerebrospinal fluid runs between each membrane and serves as a cushion protecting the spinal cord.
A pair of nerve roots emerges from the spinal cord at each vertebral level of the spine. Nerves are cordlike bundles of fibers that are responsible for conveying impulses from the central nervous system to other regions of the body. There are thousands of spinal nerves that send and receive signals from the brain.