The spinal column extends from the base of the skull to the tailbone and is made up of thirty-three bones, known as the vertebrae.
The first seven vertebrae (cervical vertebrae) are in the neck and are numbered C1 through C7. Nerve compression in this area can cause neck pain, which may radiate down the arms to the hands and fingers.
The next twelve vertebrae make up the thoracic region (T1 through T12). The ribs attach to these vertebrae and protect the heart and lungs. Few spinal problems occur in this region; it is usually very stable due to its support from the rib cage.
The lumbar region is the lower back, which contains five vertebrae (L1 through L5). The lumbar spine plays a significant role in motion and flexibility. It is the source of most motion and supports most of the body weight. Overload or taxing movements may strain the structure, compress the nerves and cause back pain, which may radiate down the legs to the feet.
The regions beneath the lumbar spine are the sacrum (S1 through S5) and coccyx (a series of small bones often called the tailbone). These are fused and do not have discs between them.
Each vertebra is composed of a body and a spinous process that protects the spinal cord and nerve roots.
The vertebrae in the cervical, thoracic and lumbar regions are separated by discs. Discs serve as cushions between the vertebrae, helping also to protect them and the nerves that run from the spinal cord to the rest of the body.