Anatomy of Degenerative Disc Disease

Degenerative disc disease affects many parts of your spine. To understand how, you first need a basic understanding of what makes up your spine.

First of all, you have vertebrae, labeled in the image below as the "Vertebral Body." In your backbone, or vertebral column, you have 33 vertebrae.

Parts of the Spine

Your spine is divided into regions: there's your neck (cervical spine), mid-back (thoracic spine), and low back (lumbar spine). At the lower end of your spine, you also have the sacrum and the coccyx, which is commonly called your tailbone. Degenerative disc disease is most likely to occur in your cervical spine or your lumbar spine.

The vertebrae in your neck are labeled C1-C7, meaning that you have seven vertebrae in that region. Most adults have 12 vertebrae in the thoracic spine (T1-T12), which goes from your shoulders to your waist. Then there are five vertebrae in your low back (L1-L5), and below that, your sacrum is made up of five vertebrae between the hipbones that are fused into one bone. The coccyx is small fused bones at the very tail of your spine (hence the tailbone).

In between your vertebrae, you have intervertebral discs (also labeled on the above image). These act like pads or shock absorbers for your spine as it moves. Each disc is made up of a tire-like outer band called the annulus fibrosus and a gel-like inner substance called the nucleus pulposus. Degenerative disc disease changes the discs and makes them less able to cushion your movements. With DDD, your intervertebral discs also become more prone to problems; they may bulge or herniate.

Together, the vertebrae and the discs provide a protective tunnel (the spinal canal) to house the spinal cord and spinal nerves. These nerves run down the center of the vertebrae and exit to various parts of the body, where they help you feel and move. You can see the spinal cord running through the vertebrae in the image.

Your spine also has facet joints, which are on the posterior side (back) of your vertebrae. These joints (like all joints in your body) help facilitate movement and are very important to your flexibility.

Your spinal joints are covered by cartilage, which protects your bones as you move. Without cartilage, your bones would rub together—very painful. Unfortunately, your cartilage can be affected by general wear and tear on your spine, and it can wear away. That's when bone spurs (osteophytes) can form as your body attempts to repair itself (you'll learn more about that in the Causes of Degenerative Disc Disease article).

Your back also has muscles, ligaments, tendons, and blood vessels. Muscles are strands of tissues that power your movement. Ligaments are the strong, flexible bands of fibrous tissue that link the bones together, and tendons connect muscles to bones. Blood vessels provide nourishment. These parts all work together to help you move.