The spine is a column of 33 bones, called vertebrae, that stack on top of each other, extending from the base of the skull to the tailbone. Most vertebrae are separated by discs that act as shock absorbers for the spine.

The spinal column is the main structure to support movement. The structures of the spine also surround and protect the spinal cord, which is a soft bundle of nerves that stretches from the base of the brain to the lower back. The spinal cord allows complex communication between the brain and the body.

The spine is also sometimes called the spinal column or backbone.