Rib
Ribs are classed as flat bones which usually have a protective role in the body. Humans have 24 ribs, in 12 pairs. All are attached at the back to the thoracic vertebrae, and are numbered from 1–12 according to the vertebrae they attach to. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body most of the ribs are joined by costal cartilages to the sternum. The ribs connect to the vertebrae with two joints, the costovertebral joints.
Rib cage
The terms "true ribs" and "false ribs" describe rib pairs that are directly or indirectly attached to the sternum. The first seven rib pairs known as the "fixed" or vertebrosternal ribs are the "true ribs" () as they connect directly to the sternum; the next five pairs (eighth to twelfth) are the "false ribs" (), or vertebrochondral ribs as they connect indirectly to the sternum via the costal cartilages of the ribs above them. Their elasticity allows rib cage movement for respiratory activity.