The spine, also called the backbone, plays a vital role in stability, smooth movement and protection of the delicate spinal cord. It is made up of bony segments called vertebrae with fibrous tissue called intervertebral discs between them. The vertebrae and discs form the spinal column from the neck to the pelvis, giving symmetry and support to the body.
The thoracic spine is the central part of the spine, also called the dorsal spine, which runs from the base of the neck to the bottom of your rib cage. The thoracic spine provides the flexibility that holds the body upright and protects the organs of the chest.
The lumbar spine is composed of the lower 5 vertebrae, which have been numbered L1–L5. The lowest vertebra of the lumbar spine (L5) is connected to the top of the sacrum, which is a triangular bone present at the base of the spine fitting into the two pelvic bones. In some cases, an extra or sixth lumbar vertebra may be present.