The annulus fibrosus is the tough, outer layer of an intervertebral disc, which is found between the vertebrae in the spine. It consists of several layers of collagen fibers that provide strength and stability, helping to contain the inner gel-like substance called the nucleus pulposus. This structure plays a crucial role in absorbing shock and allowing for movement in the spine. In addition to its supportive function, the annulus fibrosus helps to protect the nucleus pulposus from injury and degeneration. When the annulus fibrosus is damaged, it can lead to conditions such as herniated discs, which may cause pain and discomfort in the back and surrounding areas.