The human spine is essentially a bony cage that serves to provide support and structure to the body as well as to protect the spinal cord. The spine is divided into three regions, each of which contains a certain number of segments: cervical (7), thoracic (12), and lumbar (5).
Each segment is defined by a vertebral body and the vertebral bodies are separated by gel-like structures called discs. These semi-solid discs provide support, but are flexible enough to allow mobility of the spine so that you can bend and twist.
At each spinal segment, there are also a pair of facet joints that provide additional support and mobility.
The spinal cord runs down through the middle of the spinal canal, and at each vertebral level, there are spinal nerve roots that radiate out to different parts of the body. This network of nerves serve to transmit signals to and from the brain. These signals have both a sensory (touch, pressure and pain) and motor (muscle control) function.