The spine, vertebral column or backbone, is the central support of the body. The spine is formed from a series of linked bones, the vertebrae, which extend from the skull down to the coccyx, the tail-bone. The vertebral column, along with the cranium (skull), hyoid bone and the various bones of the thorax (chest), form the axial skeleton.
The design of the spine is such that it forms a shallow S shape. However, in many people the 'S' is more exaggerated than usual, often as a result of poor posture and mis-use, which can result in back problems.
The vertebrae are separated from each other by the intervertebral discs, which act as shock absorbers and allow the spine to be flexible. The spine can both curve and rotate in varying amounts within the different spinal regions, according to the design of the vertebrae.
The spinal cord, which is part of the central nervous system, carries nerve impulses to and from the brain and passes down the spine through the central canal of the vertebrae. There are also 31 pairs of spinal nerves, part of the peripheral nervous system, which connect the brain and spinal cord to the body. The nerves leave the spine through the gaps between the vertebrae and supply the whole body with a network of motor and sensory nerves.
It is therefore very important to maintain the length in the spine and to avoid any compression or habitual twists in the torso, as these reduce the space available between the vertebrae, squash the discs and eventually irritate or damage the nerves. It is possible to learn how to do this, with the help of Alexander lessons.
The spinal column is divided into five regions, according to the shape and function of each group of vertebrae. These regions are listed below, just as they are found in the spine, from top to bottom: