The vertebral column is made up of 31 separate bones called vertebrae. These interlock to form a strong flexible column, through which the spinal cord runs. They short pieces of bone, with ring-like hole which encloses the spinal cord. Except for the sacral and coccygeal ones, each vertebra is separated from the others by a disk of cartilage. Extending from the base of the skull, the vertebral column is composed of 7 cervical (neck), 12 thoracic (dorsal), and 5 lumbar (lower back) vertebrae, plus 5 sacral and 2 coccygeal, which are fused together.