Healthy spine. Coloured magnetic resonance imaging (MRI) scan of a healthy human spine seen from the side (sagittal section). The front of the spine is on the left. The spine is a flexible column of 33 bones called the vertebrae (red blocks), which are separated by intervertebral discs (white) made of cartilage. It extends from the base of the skull to the bottom of the back, supporting the head and trunk as well as enclosing and protecting the spinal cord.
