About Your Spine
The spine has a column of building blocks called vertebra. There are seven vertebrae that make up the cervical spine, twelve in the thoracic region and five in the lumbar region. The remainder form the sacrum and coccyx.
The vertebra form a bony tunnel called the spinal canal in which the spinal cord runs. The cord is a collection of nerves which link the brain and the body. It runs from the brain to the first or second lumbar vertebrae. The cord is protected by three membranes called meninges. The outer membrane is called the dura, the space between the spinal canal and the dural sac is called the epidural space.
The vertebras are linked by an intervertebral disc at the front and by two facet joints at the back. The intervertebral discs formed of a tough outer part called the annulus, and a softer inner part called the nucleus pulposus. The nucleus pulposus is a gelatinous substance which helps articulate the vertebra and cushion the spine.
The disc can efficiently absorb compressive and jarring forces but is more susceptible to twisting forces which can result in the outer layers weakening and occasionally tearing or stretching.
The facet joint is the joint between the vertebrae towards the back of the spine. The surfaces of the facet joints are cartilage lined and they are lubricated with synovial fluid.
Like other joints in the body they can wear (degenerate). Degeneration of both the discs and facet joints are part of the normal ageing process. These changes are often widespread and cannot be reversed. Any wear on a joint can produce arthritis.
The spinal nerve roots exit the spinal canal through foramina (holes) between the vertebra and facet joints. They are often compressed or irritated by surrounding tissues which can result in the patient experiencing leg pain, back pain or arm pain. This is known as sciatica when it affects the legs and radiculopathy in the arms.