Structure of Spine

Our spine consists of 33 small bones – each known as a vertebra. These are held together by various strong muscles and ligaments attached to them. Spine is a very strong but flexible structure. There are 7 vertebrae in neck, 12 at the back of chest and 5 in lower back. Other vertebrae are fused in tail bones. Thoracic vertebrae form part of rib cage which moves during breathing. Those in neck and low back are involved in movements in different directions and, therefore, more liable to wear and tear and resultant pain. Central body of the vertebra bears weight. Muscles are attached to 3 processes arising from vertebra. An arch on the back of the body of vertebra transforms it into a canal which protects spinal cord from injury. Spinal cord, a bundle of nerve fibers, is a vital structure that transmits signals from and to the brain. There are 3 joints between two adjacent vertebrae. One of these is in the form of a fibrous disc intervening bodies of two vertebrae. Intervertebral disc, which acts as a shock absorber, consists of a strong fibrous outer ring and a soft central nucleus. Discs in neck and lower back region are thicker and allow free movement. Nerves supplying trunk and extremities emerge from an opening behind the disc and can get compressed if disc is damaged. Spine starts from the base of skull and ends at a joint (known as sacroiliac joint) with pelvic bones. Spine has normal curvatures – backwards in thorax and forwards in neck and low back. It supports head and trunk over the pelvis in upright posture, protects many vital organs and provides attachment for various muscles and ligaments. It also transmits body weight in erect position, acts as a shock absorber during load bearing and serves as a foundation for extremities.

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