Understanding the back
The
spine is made up of many bones called vertebrae. These are roughly circular and
between each vertebra is a 'disc'. The discs are made of strong 'rubber-like'
tissue which allows the spine to be fairly flexible. A disc has a stronger
fibrous outer part, and a softer jelly-like middle part called the nucleus
pulposus.
The
spinal cord, which contains the nerves that come from the brain, is protected
by the spine. Nerves from the spinal cord come out from between the vertebrae
to take and receive messages to various parts of the body.
Strong
ligaments attach to the vertebrae. These give extra support and strength to the
spine. Various muscles also surround, and are attached to, various parts of the
spine. (The muscles and ligaments are not shown in the diagram below for
clarity.)
What is a prolapsed disc?
When
you have a prolapsed disc (commonly called a 'slipped disc'), a disc does not
actually 'slip'. What happens is that part of the inner softer part of the disc
(the nucleus pulposus) bulges out (herniates) through a weakness in the outer
part of the disc. A prolapsed disc is sometimes called a herniated disc. The
bulging disc may press on nearby structures such as a nerve coming from the
spinal cord. Some inflammation also develops around the prolapsed part of the
disc.
Any
disc in the spine can prolapse. However, most prolapsed discs occur in the
lumbar part of the spine (lower back). The size of the prolapse can vary. As a
rule, the larger the prolapse, the more severe the symptoms are likely to be.
Who gets a prolapsed disc?
Bouts
of back pain are very common. However, less than 1 in 20 cases of acute (sudden
onset) back pain are due to a prolapsed disc. (Most cases on back pain are
classed as 'simple low back pain'. This is thought to be caused by a minor
problem to a muscle, ligament, or other structure in the back. For example, a
strained muscle. See separate leaflet called 'Low back Pain in Adults' for a
general overview of the different types of back pain.)
The
commonest age to develop a prolapsed disc is between 30 and 50 years. Twice as
many men as women are affected.
What causes a prolapsed disc?
