Functions

The vertebral column, or spine, is a complex system of bones, intervertebral discs, ligaments, muscles and nerves, designed to fulfil many seemingly incompatible functions.

It must offer support to the body (to hold us upright) whilst allowing a large range of movement in many directions.
The spine also functions to protect the delicate spinal cord that carries nerves to every part of our bodies, as well as acting as a shock absorber to decrease the forces transmitted to the brain when walking, running, jumping etc.

Vertebrae

The bones of the spine – the vertebrae – are stacked one upon another, separated by discs, in such a way that three normal curves are maintained – slight inward curves at the neck (cervical) and lower back (lumbar) areas, and an outward curve in the chest (thoracic) area. These curves and discs are mainly responsible for shock absorption.

Each vertebra is attached to the next by a complex of three joints.

Ligaments

Many ligaments bind these bones and discs together. They surround the joints of the spine, some being short and travelling the distance of only one or two vertebrae, others being longer, travelling over several vertebrae to the entire length of the spine. These ligaments are partially responsible for the support function of the spine, preventing the vertebrae from slipping “out of place”.

Muscles

Muscles surround and are attached to the vertebrae to provide movement, or add to stability. In general, muscles perform one of two functions. Some produce movement of joints – these muscles are typically long and thin, can act quickly, producing high tension over short periods of time.

Other muscles are designed specifically to provide stability across joints – they are generally shorter and thicker, supplying low tension for extended periods of time. They produce small movements constantly, and “fine-tune” the position of the joints – these are our postural muscles.

Stability

Stability of each spinal segment – each vertebra and its joints – is essential for pain-free movement. Any movement of any part of the spine puts a strain on the spine and its surrounding structures. Any movement of other body parts also impacts upon the spine, causing stress to the structures of the spine.

All Things Are Connected

The legs are attached to the spine via the pelvis, with leg movements causing movement of the pelvis and therefore of the spine (remember that old song “the knee bone’s connected to the thighbone…”? It’s true – all the bones in the body are ultimately connected … to the spine!)

Similarly, the arms are connected to the torso via the clavicle (collarbone) and scapula (shoulder blade). Therefore movement of the arms ultimately puts stress on the spine.

This is why stability of the spine is so important – every movement you make is putting stress on your spine, and if the spine is not being held stable, the spinal joints will have more movement imposed upon them, putting more stress on the joints and surrounding structures.