CHAPTER 1
A�ATOMY OF THE SPI�E
The spine consists of bones ( vertebrae ) that encircle and protect the spinal cord . These vertebrae are responsible for allowing the spine to move while protecting the spinal cord . To allow for movement and stability , the vertebrae interlock with one another by means of a joint on either side , one on the left and one on the right . The vertebrae are also separated from one another by intervertebral discs .
The discs are made of a type of cartilage . The intervertebral disc is made up of a soft , gel-like centre , called the nucleus pulposus , and this gel is contained by a tough outer fibrous ring-like structure arranged in layers , called the annulus fibrosus . The vertebrae of the spine are further kept in position by an array of ligaments . Muscles also attach to the vertebrae . Nerves leave the spinal canal , formed by the arches of the vertebrae , through small openings formed between the sides of the vertebrae , called the neural foramina .
There are 7 neck ( cervical ) vertebrae , 12 chest ( thoracic ) vertebrae , 5 lower back ( lumbar ) vertebrae and 5 sitting-bone ( sacral ) vertebrae . The sacral vertebrae are fused into a single mass called the sacrum or sitting-bone .
It is unusual for the thoracic spine to undergo wear and tear changes as it is stabilised by the rib cage that is attached to it . The cervical spine and the lumbar spine on the other hand are subject to a lot of movement and this is where most of the wear and tear takes place . The lower part of the neck where it attaches to the rigid thoracic spine , stabilised by the ribs , is under a lot of biomechanical stress . The lower part of the cervical spine is therefore more prone to wear and tear .
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