The osteology of the African elephant (Loxodonta africana): vertebral column, ribs and sternum.

The vertebral column, sternum and ribs of the African elephant were studied and illustrated. In the cervical series, the vertebrae are characterized by very short (compressed) vertebral bodies and short spinous processes. There are 20-21 thoracic vertebrae that carry ribs, and three lumbar vertebrae. The neural arches of the five sacral vertebrae fuse with each other as well as with the wings of the ilium, while the intervertebral discs do not ossify and the vertebral bodies remain separate. There are 19-21 caudal vertebrae. In the latter, the neural arches of only the first five to six vertebrae fuse dorsally, the vertebral foramens of the other vertebrae as well as the vertebral canal remain open dorsally. The body of the first rib is greatly expanded while that of the last three to four ribs are reduced. The cartilages of the first six ribs articulate with the sternum, the last five to six ribs do not bear costal cartilages and are not attached to the costal arch. The sternum consists of five sternabrae that form three approximately equal, but separate, segments. The first segment is formed by the first sternabra, the second segment is formed by the second to fourth sternabrae and the last segment is formed by the fifth sternabra. The first and second sternabrae articulate with each other by means of a synovial joint, the second to fourth sternabrae are fused to each other and the fourth and fifth sternabrae are loosely attached to each other by connective tissue.