Vertebrae (singular: vertebra) are the individual irregular bones that make up the spinal column (aka ischis) – a flexuous and flexible column. There are normally thirty-three (33) vertebrae in humans, including the five that are fused to form the sacrum (the others are separated by intervertebral discs) and the four coccygeal bones which form the tailbone. The upper three regions comprise the remaining 24, and are grouped under the names cervical (7 vertebrae), thoracic (12 vertebrae) and lumbar (5 vertebrae), according to the regions they occupy. Each vertebra has a hole through which the spinal cord passes.

• Gray's Anatomy: The Vertebral column - The 1917 Gray's Anatomy is available via the Bartleby project. It is available with full colour diagrams, and provides an excellent starting point in anatomy, as well as a relatively complete source for gross anatomy. This article was copied and pasted from the 1917 Gray's Anatomy, which is in the public domain.
• Smart implant will help broken vertebra Archived 2007-09-29 at the Wayback Machine - An article from IsraCast