The main job the spine has to do is to act as a foundation or frame for the other parts of our body to hang from. Since we now walk upright our spine also has to carry a fair amount of weight. To enable movement joints are needed.
Our spine acts as a casing to enclose and protect the main communication lines from our brain - our spinal cord. Openings occur at intervals all down the length of our spine which contain nerves going to all other parts of the body.
In total there are 24 bony blocks or vertebrae. The five largest of these are at the base or lower back and carry most of the weigfht . Above these are the twelve which contain the chest and have our ribs attached. At the very top of the spinal column are the seven cervical or neck vertebrae. These blocks of bone or vertebrae gradually increase in size from the top down to the base - rather like a columnar pyramid but have 2 distinct curves when viewed from the side.
The shape of these curves is determined by the structure and shape of the joints between each vertebrae - the discs.
Projecting out from both sides of the spine at the rear of each vertebrae are two arms called pedicles which are joined to each other by laminae or plates of bone which form the back wall of the nerve trunk canal. Each vertebra is joined to the one above and the one below it by a joint called a disc. To keep the spine relatively stable there are two additional joints known as facet joints coming out from the back of the pedicles and laminae. These slide up and down against each other and determine the extent and direction of movement by their shape and angle. They allow us to bend our spine from front to back and side to side.
To move our spine requires muscles and these in turn need to be attached to something to provide leverage. We also need attachments for holding ligaments and limiting excessive movement. These attachments are known as spinous processes and spread out sideway and rearwards from the pedicles. The rearward facing process is actually the knobbly part our spine which can be felt from the outside. When standing up straight these can be felt as a more or less vertical line.
Thus some of the main functions of the spine are: an ability to carry weight, provision of stability to the body and to act as a protective covering for our main communication lines from our brain. In the next section of our blog we will deal with those most important parts of the spine which enable movement namely the discs.