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Spinal Column

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Anatomy Of The Spine

Spinal Column

The spine is a flexible column, composed of a stack of individual bones. Each bone is called a vertebra. There are seven vertebrae in the neck (cervical vertebrae) twelve in the thoracic region (thoracic vertebrae) and five in the lumbar region (lumbar vertebrae). At the top, the skull rests on the atlas vertebra (the first cervical vertebra). This is called the occipito-cervical junction. At the bottom, the fifth lumbar vertebra rests on the sacrum (a large triangular bone) which consists of five fused vertebral elements. The sacrum forms part of the pelvis. Below the sacrum, there is a small string of bones, the residual tail, called the coccyx. This is composed of up to six or seven segments.

The vertebrae are separated from each other by joints. At the front, there is a large fibro-cartilaginous joint, called a disc. At the back, there are facet joints. The bones are bound together by ligaments. The most important of these are the anterior longitudinal ligament, the posterior longitudinal ligament and the ligamentum flavum (see diagrams).

Down the centre of the spine there is a canal – the vertebral or spinal canal. In this canal, we find the spinal cord and spinal nerves.