UNDERSTAND YOUR ANATOMY

The spine consists of 26 bones stacked like blocks (called vertebrae) separated by a cushion or shock absorber (intervertebral disc). This forms the support beam for the rest of the body to which is attached the muscles. These vertebrae are divided as: seven for the neck, 12 in the chest, five in the low back, the rest in the sacrum and tail bone.

Within the canal that runs through, there is a tube containing fluids and nerves. Between each set of vertebra, a pair of spinal nerves go out to appropriate parts of the body. They supply muscles movement and sensation to the skin and body.

Connecting between the vertebra are ligaments supporting the body along with the muscles that move the body. Because the cervical and lumbar spines are more mobile, they are subject to increasing stress causing pain in the spine. 

The part of the spinal cord where the nerve originates may be disturbed, for example, by a ruptured or slipped disc, or by an inflammation in the vertebral bones. An abnormal condition in a nearby blood vessel may cause it to press on the nerve. Acute and prolonged constipation is sometimes responsible because the accumulation in the bowel exerts pressure on the nerve or the body absorbs unexcreted toxic substances to which the nerve reacts

External conditions or occurrences may precipitate a sciatic disturbance, such as a bad fall or severe contortion of the body, prolonged pressure to cold and dampness. Sometimes sciatic neuritis is actually pressure of one of the bones of the spine on the nerves that come to the sciatic. This condition is frequently called "slipped disc".

This usually occurs in people between the ages of 30 to 50, although they can be seen in both younger and, less frequently, older patients. The cause of prevalence of slipped disc in this age group is from the changing composition of a disc.

A disc has two layers: 1) the outer annulus is made up of tight fibers, 2) the inner nucleus pulposus, is jelly-like and under high pressure. Before the age of 30, the outer annulus is strong and prevents the soft inner nucleus from extruding. As we age, the outer annulus weakens. Because of the higher pressure in its center, cause the disc to bulge. A slipped disc occurs when the outer annulus weakens so much a rent or hole forms through which the jelly-like inner nucleus pulposus escapes. The accompanying leg pain is typically caused by the now freed disc jelly pressing on a nerve root. The back pain that an individual experiences may be caused by the hole in the outer annulus.