Spinal nerves carry nerve impulses to and from the spinal cord through two nerve roots:
In the center of the spinal cord, a butterfly-shaped area of gray matter helps relay impulses to and from spinal nerves. The "wings" are called horns.
Impulses travel up (to the brain) or down (from the brain) the spinal cord through distinct pathways (tracts). Each tract carries a different type of nerve signal either going to or from the brain. The following are examples: