Your back is composed of twenty-four individual bones called vertebrae that are stacked one on top of the other to make up your backbone or spinal column. The entire column sits on the sacrum, a large triangular bone that connects the spine to the hips. The top seven vertebrae in the neck are called the cervical spine. The next twelve segments make up the mid back or thoracic spine, and the bottom five bones in the lower back are called the lumbar spine. Each bone is unique in its size and shape, but they all have several things in common.