Bulging Disc

We’ll note at the start that a “bulging disc” is not the same as a “herniated disc.”

The spine is made up of a series of individual bones called vertebrae that are stacked to form the spinal column. Between the vertebrae are flat, round, rubbery cushions known as intervertebral discs, which act as shock absorbers and keep the spine flexible. Each disc has a soft, gel-like center, called the nucleus pulposus, surrounded by a tough, fibrous outer layer called the annulus.

When these intervertebral discs deteriorate with age, they may lose fluid and become dried out. As this happens, these cushioning discs become compressed. This may lead to a breakdown of the tough outer annulus ring. In turn, this lets the nucleus pulposus to bulge out. This is called a bulging disc (or disc protrusion).

Note that the term “disc” is often used interchangably with the alternative “disk.” In both cases, we are referring to the same intervertebral discs (or intervertebral disks).

What is the Difference Between a Bulging Disc and a Herniated Disc?

A bulging disc bulges out around the circumference of a disc, but it remains whole. However, if the bulging disc continues to break down or stress the spine, the situation can worsen. The inner nucleus pulposus of the disc may rupture out from the annulus. This is known as a or herniated, or ruptured, disc.

With a herniated disc, the fragments of disc material can then press on the nerve roots located just behind the disc space. This condition can cause pain, weakness, numbness, or changes in sensation.

Bulging Disc Symptoms

The symptoms of a bulging disc are usually progressive and gradual. It can cause pain in the buttocks, legs, or back. It can also affect your ability to walk.

Bulging discs generally occur with multiple discs at the same time. It can also cause other disc degeneration-related issues, like lumbar stenosis.

Illustration of a bulging disc between the vertebrae in a spine.
In the illustration above, a bulging disc presses on nerves, causing pain. However it has not ruptured as is the case with a herniated disc.