Lower spine. Coloured 3-D computed tomography (CT) scan of the bones of the lower spine, seen from the rear. The spine is made of a column of 33 cyl- indrical bones called vertebrae, five of which are seen here. Between the vertebrae are flexible joints that both stabilise the spine and allow movement. The bony projections here are behind the cylindrical part of each vertebra, and provide at- tachment sites for the muscles and ligaments that hold the spine together. The pelvis can be seen at lower left and right. Running through the spine is the spinal cord (not seen), a bundle of nerves from the brain. 3-D CT scans are made from multi- ple X-rays combined into one image by a computer.