The discs that sit in between each vertebra are incredibly strong and resilient. Each is made of a tough outer layer of collagen fibers, called the annulus fibrosus, surrounding a soft core of a gel-like substance called the nucleus pulposus. The two structures work together to distribute pressure across the disc; this provides essential cushioning between the vertebrae and allows for bending, twisting, shock absorption, and weight bearing.
Thinned disc: The more the discs are compressed, the looser and weaker the fibers of the annulus fibrosus become, and tears can develop in the annulus. In addition, the nucleus pulposus can lose fluid. Both of these conditions contribute to discs thinning over time.
While this may sound like permanent damage, degenerative discs can heal if given the chance. The inflammatory process automatically kicks in to repair the disc, and if compression on the spine is reduced and muscular patterns are improved, degenerative discs can heal and resume their normal size and function. However, the annulus fibrosus has a limited blood supply, so doctors estimate that the healing process can take up to two years.
Bulging disc: When compression is constant, a disc may bulge or protrude from its normal boundaries. Sometimes it will press on a nerve root or the spinal cord, causing pain or another nerve sensation. If the bulge doesn’t press on nerve tissue, you may not feel anything at all.
Herniated disc: This is the same as a ruptured disc. If a disc is put under a great deal of strain from constant compression or a sudden increase in pressure, the contents of the nucleus pulposus can push out through a tear in the annulus. If the herniation presses on a nerve root, you may experience pain, numbness, or weakness.