ABSTRACT
The curved, flexible column that forms the central axis of the skeleton supports the weight of the head, trunk and upper limbs and transmits it through the pelvic girdle to the lower limbs. Its great strength derives from the size and articulation of its bones, the vertebrae, and the strength of the ligaments and muscles that are attached to them. There are 33 vertebrae, united by cartilaginous discs (which contribute about onequarter of its length) and ligaments. The column is about 70 cm long and within its canal contains and protects the spinal
cord. There are five groups of vertebrae, each with specific characteristics: cervical (7), thoracic (12), lumbar (5), sacral (5) and coccygeal (4).
