Your central nervous system is made up of your brain and spinal cord.

Your spinal cord is a bundle of nerve cell bodies and fibers. It is soft and pliable, but strong.

Your spinal cord is about half an inch wide, a little smaller than a dime.

It is about 17 inches long and extends from your brain to your lower back. The portion of the spinal cord just above your waist is called the conus medullaris. Below the conus medullaris are nerve roots called the cauda equina.

Your backbone is made of 33 bones called vertebrae. Each of your vertebrae has an arch and…

…stacking them forms a tunnel. This tunnel is called the spinal canal and your spinal cord runs through it. The vertebral column gives support and flexibility to your body and protects your spinal cord.

Between each of your vertebrae are tough, fibrous vertebral discs, acting like cushions. Your vertebral discs stop your vertebrae from rubbing against each other and protect your spinal nerves where they exit between vertebrae.

Spinal nerves branch from your spinal cord. There are 31 pairs of spinal nerves and they are named by the vertebrae they pass through. There are 5 sections of the vertebral column and spinal cord: cervical, thoracic, lumbar, sacral, and coccyx. Each vertebrae and pair of spinal nerves is given a letter representing its section, C, T, L, S, and Co, and a number.

In your neck there are 7 cervical vertebrae and 8 pairs of cervical spinal nerves. Your cervical spinal nerves are numbered by the vertebra below them, except C8, which exits below C7 and above T1. The rest of your spinal nerves are numbered by the vertebra above them. Your cervical spinal nerves control your neck, arms, hands, and your main breathing muscle, the diaphragm.

In your chest there are 12 thoracic vertebrae and 12 pairs of thoracic spinal nerves. Thoracic vertebrae each have a pair of ribs attached. Your thoracic spinal nerves control your trunk and upper abdomen, helping you sit, stand, and breathe.

In your abdomen there are 5 lumbar vertebrae and 5 pairs of lumbar spinal nerves. Your lumbar spinal nerves control your abdomen and upper legs.

In your pelvis there are 5 fused sacral vertebrae, called the sacrum, and 5 pairs of sacral spinal nerves. Your sacral spinal nerves control your lower legs, bowel, bladder and sexual organs.

In your tailbone there are 4 fused coccyx vertebrae and 1 pair of coccyx spinal nerves. Your coccyx spinal nerves provide sensation to your coccyx.