The intervertebral discs lie between the vertebrae. These are composed of round, spongy pads of cartilage called intervertebral discs that allow for flexibility in the lower back and act much like shock absorbers throughout the spinal column to cushion the bones as the body moves.
The outer part of the disc is composed of a fibrous envelope (annulus fibrosis). This is composed of multiple layers of specialised protein fibres (collagen).The inner part of the disc is composed of a complex protein gel (proteoaminoglycan) which absorbs water. As we age the proteins within the disc degenerate, losing their ability to retain water and the disc gradually deflates.
Bands of tissue, known as ligaments and tendons hold the vertebrae in place and attach the muscles to the spinal column.