The intervertebral disc consists of an outer fibrous body called the annulus fibrosus and an inner gel-like substance called the nucleus pulposus. It acts as a shock absorber and spacer for the spine giving room for the intervertebral neural foramina which are the portals for the exit of the spinal nerves. The nucleus pulposus contains noxious chemicals which can be irritating to nerves.

 

The intervertebral discs lie between the vertebral bodies. In front, they are bound by the anterior longitudinal ligament and behind, by the posterior longitudinal ligament. Behind the posterior longitudinal ligament lies the spinal cord.

 

Wear and tear can cause the annulus fibrosus to weaken allowing bulges. These blulges may protrude out enough to touch the spinal cord causing irritation to the nerves. These large disc bulges are termed disc herniations. With extreme forces, these disc bulges may tear the annulus fibrosus and allow leakage of the nucleus pulposus. This may be observed as sudden sharp pains radiating down the leg. The chemicals of the nucleus pulposus can cause swelling of the nerves resulting in constant burning pain. These pains are termed lumbar radiculopathy or commonly sciatica, which is usually described as pain radiating from the low back down the legs to the feet.