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27.1 Regions The bony spinal column is divided into five anatomical regions. Uppermost (cephalad) is the cervical spine. The thoracic, lumbar and sacral areas are below and the lowermost (caudad) is the vestigial remnant of the prehensile tail bones, the coccyx. They form a continuous pillar which acts as the central axis of the body which supports and transmits the weight of the head and trunk and protects the spinal cord which is contained within.

27.2 Curves There are four natural curves in the adult spine which are maintained predominantly by the muscles and other soft tissues. The cervical spine and lumbar spine sections are lordotic i.e they curve forwards [anteriorly] in the sagittal plane (convex in front and concave behind.) The thoracic spine and the sacro-coccygeal curves display a kyphosis: they curve backwards [concave at the front and convex behind].

27.3 Number Figure 1A is a drawing of the lateral view of the spine which demonstrates the component vertebrae showing the 7 cervical [neck] vertebrae, the 12 thoracic [or dorsal] vertebrae and the 5 lumbar vertebrae.

27.4 MRI Plain radiographs demonstrate the bony structures and some soft tissue shadows but the fine resolution of the soft tissues is demonstrated best by Magnetic Resonance Imaging [MRI] where in addition to the bones and joints of the spine the spinal cord, cauda equina, theca and epidural fat pads are visualised. Degeneration and dehydration of the intervertebral discs may be assessed and disc bulging or prolapse may be demonstrable on MRI scans. A sagittal section MRI scan will show not only the bony structure but also the soft tissues of the spinal cord.

27.5 Figures 2A and 2B show the anterior (front) and posterior (rear) views of the bony spine showing the individual vertebra in the cervical, thoracic and lumbar regions. The sacral vertebrae are fused. Note that the vertebrae in the thoracic spine uniquely offer support for the ribs. The coccygeal segments are rudimentary, may vary in number from 3 - 5 and demonstrate a variation in degree of angulation and of fusion.