What is a Herniated Lumbar Disc?

Before we talk about what causes a herniated lumbar disc it is worth taking a minute to refresh your knowledge of the anatomy of the human spine as it’s hard to visualise this otherwise.

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The human spinal cord runs from your brain through the human spine and is protected in a bony channel by vertebrae. The vertebrae are separated from one another by spinal discs.

At each vertebral level the spinal cord branches off to form a nerve root which leaves the spinal cord, these nerve roots are then bundled together to form major peripheral nerves. In humans there are two main nerves in the legs and they are

• the sciatic nerve running down the back of the thigh
• the femoral nerve running down the front.

The Difference Between Bulging and Herniated Lumbar Discs

A bulging lumbar disc is caused by the tough outer rings of the disc weakening which allows the softer centre of the disc to push backwards, usually more to one side then another. This bulging disc can pinch a nerve but also it can just cause swelling and inflammation which causes pain. This is why the term ‘pinched’ or ‘trapped’ nerves are not so great as often the nerve is just irritated.

A bulging lumbar disc causing lumbar radiculitis or irritation of the sciatic nerve

A disc herniation or prolapse is where the softer middle contents of the disc have actually escaped right out of the disc through the tough outer layer.

A lumbar MRI scan showing a lumbar disc prolapse

Whilst many of us will have lumbar disc bulges that show up on scans very few of us will have symptoms from them, in fact less than 5% of people with lower back pain will have trouble because of lumbar discs.

More about the Causes and Symptoms of Sciatica

From Herniated Lumbar Disc to Lower Back Pain Toolkit Home Page

07-Feb-2011