Lumbar spine in longitudinal section with a herniated disc. The square-shaped segments are the bony structures of the vertebral body, in between the discs in blue. The intervertebral disc functions similar to a joint between the elements of the spine. It consists of an outer fibrous cartilage ring (annulus fibrosus) and a softer core (nucleus pulposus). Above and below is a layer of protective hyaline cartilage. The intervertebral disc core can herniate through the fiber ring, which is called prolapse (see second disc from the bottom). Depending on the direction and at which vertebrae the prolapse occurs this can lead to severals symptoms such as pain, loss of reflexes and paresis (paralysis).
