If you look at the spine from the side, you will see that it consists of four curves. The cervical and lumbar areas curve forwards are convex internally, while the thoracic and sacral areas curve backwards are concave internally. These gentle curves are important because they increase the strength of the backbone, help to maintain balance in the upright position, absorb shock during walking and help to protect the spine from injury when you are jumping or falling.

Thirty one pairs of nerves branch out from the spinal cord. They emerge from either side through gaps between adjacent vertebrae. Although vertebrae in different regions up and down the spine vary in size, shape and detail, they typically consist of two essential parts, a solid cylindrical segment known as the vertebral body at the front, and a knobbly, roughly triangular segment known as the vertebral arch or neural arch at the back.

What about a typical vertebra? The body, which has flat upper and lower surfaces, known as end plates, is convex in front and flattened at the back. The flattened area forms the front of the spinal canal through which the spinal cord and nerve roots pass. The arch surrounds the rest of the spinal and gives protection to the structure within it.

It also has two upper and lower surfaces called facets. The lower facets of one vertebra glide along those of the vertebra below, limiting the motion of one relative to its neighbor and preventing one from slipping off the other. Facets connect the rear portions vertebrae to form joints.

A typical vertebra has a body and seven processes, one spinous process, two transverse processes and four articular processes, forming the neural arch. These processes help the vertebrae fir together and give plenty of surface area for muscle attachment.