Spinal Cord

The spinal cord, a thick rope of nervous tissue, is protected by a fluid-filled bony canal and extends along the back. The spinal cord in an adult is roughly 18 inches long and ends just above the waistline. It serves not only as a pathway for nerve signals to travel to and from the brain, but also as a center for coordinating many reflex actions independently of the brain, like jerking your hand away from something hot.