The term 'vertebra' refers to one spinal bone. Twenty-six vertebrae make up the spinal column. A vertebra consists of a body in front and a bony ring in back. The bony ring has parts that contribute to joint anatomy and that allow for muscles and ligaments to attach. The inside of the ring is a passageway for the spinal cord. Nerves branch off from the spinal cord and exit the spine by means of holes on the sides of vertebrae.