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2010-03-06
Back curves
How does the spine work?
The spine is the central pillar of the body. It supports the weight of the head and trunk, and provides a protective passage for nerves.
The spine is made up of 33 irregularly shaped bones, or vertebrae. Each vertebra has a hole in the middle through which the spinal cord runs. In between these vertebrae are discs filled with soft material, which act as shock absorbers.
Seen from behind, a normal spine is straight and stretches vertically from the head down to roughly the top of the cleft between the buttocks.
From the side, the spine has two curves: one at the top of the back bending outwards and one in the small of the lower back curving inwards.
What causes excessive curvature?
Excessive curvature of the upper spine is called kyphosis. Typically, the back appears hunched and more rounded than usual.
Poor posture may contribute to its development over the years, but diseases affecting the spine - such as osteoarthritis or osteoporosis - are responsible. Children can have kyphosis, but the cause is usually unknown.
Excessive inward curving of the lower back is called lordosis. Being overweight is a common cause. Having a large belly leads to imbalance. To compensate for this - and to prevent toppling forwards - a person will lean backwards.
Weak abdominal muscles or poor posture may also be partly responsible. Having kyphosis may even contribute to lordosis developing.
When the spine curves to the side it is called scoliosis. This occurs most often in the upper chest area or lower back and often there's no obvious cause.
It's more common for women to develop scoliosis and it can run in families. Some babies are born with congenital scoliosis. Rarely, diseases causing muscle weakness around the spine may be responsible, such as muscular dystrophy.
If the legs aren't the same length, this will cause the spine to curve.
