The Spine
The spine is made up of 24 bones called vertebra that sit on top of one another to form the spinal column. Between each vertebra is a disc which is a soft, gel-like cushion that acts as a shock absorber and keeps each vertebra from rubbing against each other. The vertebra are held together by ligaments which run up the entire length of the spinal column which give support to the spine.
Tendons join muscles to the spine which allows it to move. The spinal column has joints called facet joints that link the vertebra together and give them the flexibility to move against each other.
The vertebra help protect the spinal cord, a large collection of nerve tissue that caries messages from the brain to the rest of the body. Individual nerves exit the spine between each vertebra through spaces called the neural foramina. These nerves carry messages such as sensation and pain around the body.
The spine has three segments. The cervical spine (the neck), the upper segment consists of 7 vertebra. The thoracic spine (mid back) consists of 12 vertebra and the lumbar spine (lower back) consists of five vertebra. Below the lumbar spine is the sacrum, a group of specialized vertebra that connects the spine to the pelvis (see diagram).
The spine has a “s“ shaped curve when looking at it from the side. This helps to distribute weight through the body. Each segment of the spine relies upon the strength of the others to function properly.
Low back pain
Low back pain is described as
- Acute if it has lasted less than 6 weeks
- Chronic if it has lasted more than 12 weeks
Acute or short-term low back pain generally lasts from a few days to a few weeks. Most acute back pain is the result of injury (trauma) to the lower back . Pain from trauma may be caused by a sports injury, work around the house or in the garden, or a sudden jolt such as a car accident or other stress on spinal bones and tissues. Symptoms may range from muscle ache to shooting or stabbing pain, limited flexibility and range of motion, or an inability to stand straight or sit for long periods.
Pain can also be felt in other areas such as the legs and buttocks. This is known as referred pain.
Chronic back pain is pain that persists for more than 3 months and can be caused by a number of conditions such as a degenerative disc problem or arthritis. It can also be the result of poor management of acute conditions that become a chronic problem.
What causes lower back pain?
As people age, bone strength and muscle elasticity tend to decrease. The discs begin to lose fluid and flexibility, which decreases their ability to cushion the vertebrae. Pain can occur when, for example, someone lifts something too heavy or overstretches. This can cause the soft tissues around the spine such as the ligaments and muscles to strain. This can damage the tissues directly and in turn can cause surrounding muscle spasm. When you experience a muscle spasm, it is because your muscle tightens up and will not relax. These spasms usually occur as a reflex, meaning that you cannot control the contraction of these muscles. When any part of the spine is injured, including, a disc, ligaments, bones, or muscles, the muscles automatically go into spasm to reduce the movement around the area. This protective mechanism is designed to protect the injured area and can be a very painful experience.
If the spine becomes overly strained or compressed, a disc may rupture or bulge outward. This rupture may put pressure on one of the nerves exiting the spinal column. This irritation or compression of the nerve can lead to pain.
