Annular tears, also known as annular fissures, occur when the fibers that make up the annulus (the outer covering of the intervertebral disc) either separate from one another or are severed from their place of insertion on the nearby spinal bone. A tear may also be a break through the fibers of one or more of the layers of the annulus. Annular tears sometimes lead to herniated discs.
Trauma to the spine may cause an annular fissure, but often this injury is the result of long-term wear and tear. Small, imperceptible injuries to the disc and surrounding structures occur routinely because of sitting, lifting, twisting your spine, and other common movements. Over time, these small traumas may escalate to the point of injury to one or more annular fibers.
After about age 10, annular tears are common, especially in the low back. By the time you reach middle age, you'll most likely have developed as many annular tears as you ever will.