Spinal Column
. Spinal Column, common name applied to the structure of bone or cartilage surrounding and protecting the spinal cord in vertebrate animals (see Animal). It is also called a vertebral column, spine, or backbone, ANATOMY AND PHYSIOLOGY The spinal column forms the major part of the skeleton. To it are attached the skull, shoulder bones, ribs, and pelvis. In very primitive animals having a vertebral column, the spine consists of a solid cartilaginous rod known as the notochord. Although remnants of the notochord persist in the cartilages that form part of the apparatus connecting adjoining vertebrae, in higher animals the notochord is replaced by a series of separate bones called vertebrae. The shape and number of vertebrae vary among different animals. In general, the vertebrae are stacked like a column of poker chips and are held together by ligaments, the connective tissue that holds bones together at a joint. In humans the spinal column contains 33 vertebrae: 7 cervical vertebrae in t