What is a Disc Tear?

tearing of the discs annular tissue

Before describing what a torn disc is and it's effects on the body, it's necessary to first understand the physical makeup of a vertebral disc and its functions. The two main parts of the vertebral disc are the annulus fibrosis and the nucleus pulposus. The Annulus is the tough outer shell that contains the nucleus, a soft gel like substance called the nucleus pulposus. There is a disc located between each of our vertebrae in the spine providing us with stability, and also acting like a shock absorber.

What Is a Torn Disc?

A torn disc generally refers to a tear in the annular tissue (the outer layer of the spinal disc). A disc tear is typically caused by a combination of disc degeneration and trauma. When this combination occurs, the central disc material (nucleus) often moves into the torn area of the outer layer of the disc, forming an interpositional disc herniation. A torn disc can also escelate in severity when a portion of this nucleus seeps through the tear leading to a herniated disc.

One of the easiest ways to understand a torn disc is to picture a jelly donut.  The jelly inside would be the nucleus, while the donut exterior would be the annulus.  As the donut starts to get stale and dry up little cracks begin to form, and once these cracks tear, some of the jelly seeps into and eventually through the tear.  Although a torn disc is technically a little more complicated than this, this is the basic concept behind it.

The Difference between a Healthy Disc and a Disc Tear

A healthy disc is composed of a tough outer shell and a soft inner material called the nucleus pulposus. When a disc tears, the tough outer shell either cracks or tears allowing the inner material to seep through, causing painful disc tear symptoms.

The figures below show the differences between a healthy disc and a torn disc.

Healthy Lumbar Disc with no disc tears or seepage
Figure 1a. Healthy and strong vertebral disc.
Spinal disc tear with nucleus herniating, leading to pressure being placed on the spinal nerves.
Figure 1b. Disc degeneration that has resulted in a torn disc.