Each vertebral bone in the spine is connected to another by an intervertebral disc, which has a strong outer ring of fibrous tissue called the annulus fibrosus. The annular fibers surround the soft jelly-like center of the disc, called the nucleus pulposus. They are responsible for connecting the vertebra together and serve to distribute pressure evenly across the disc. The nucleus serves as a shock absorber. The outer third of the annular ring is filled with pain fibers, and if it is injured, it can cause debilitating pain. A tear may heal over time, but it will leave one prone to future tears and injury. An annular tear may also lead to premature disc, facet joint, and endplate degeneration.