Spine. Computer illustration of three views of a healthy human spine. It is seen from the back at left, the side at centre, and from the front at right. The spine is a column of 33 cylindrical bones called vertebrae which support the trunk and head and protect the spinal cord. Between the vertebrae are intervertebral discs (brown) which allow a degree of flexibility and cushion the vertebrae during movement. Each vertebra has bony projections which provide attachment sites for the muscles and ligaments that hold the spine together. Running through the spine is the spinal cord (not seen), a bundle of nerves which links the brain to the rest of the body.