The spinal cord and the brain make up the central nervous system (CNS). The spinal cord relays information to and from the brain in the form of electrical signals that travel through nerve fibers between the brain and the rest of the body. This pathway of information is necessary for sensation, movement and autonomic functions such as heartbeat and bladder control. Any interruption in this process, such as that caused by traumatic injury or tumor, may result in loss of sensation, motor function or bodily functions.

The spinal cord is a delicate structure that closes to form a neural tube during fetal development. The entire CNS develops from the neural tube. The spinal cord itself usually extends down to the first lumbar vertebra and divides into several individual nerve roots.

Two spinal nerves extend out at each vertebral level. There are 31 pairs of these spinal nerves in the neck and back. In the part of the back where the spinal cord ends, a group of nerves called the cauda equina continue down. Compression of these nerves, a condition known as cauda equina syndrome, demands immediate medical attention. Left untreated, cauda equina syndrome can cause permanent neurological damage.

The spinal cord is encased in the spinal canal, which is formed by the alignment of the bones and ligaments of the spinal column. The spinal cord is covered with three membranes known as meninges. The tough outermost layer called the dura mater encloses the brain and spinal cord to prevent the protective cerebrospinal fluid from leaking into the central nervous system.

The epidural space is the region between the dura mater and the spinal canal. It is filled with tissues and vessels. Medications such as anesthetics and corticosteroids are sometimes injected into the epidural space to relieve pain and inflammation on nerve roots.