In the human body, the rib cage normally contains 12 pairs of ribs.
That gives most adults 24 ribs in total, arranged on the left and right sides of the thorax. Ribs curve from the thoracic vertebrae toward the front of the body and help protect the heart, lungs, and major blood vessels. They also move with the muscles involved in breathing.
The first seven pairs are called true ribs because they attach directly to the sternum through their own costal cartilage. Pairs eight through ten are false ribs because their cartilage joins the cartilage above rather than reaching the sternum independently. Pairs eleven and twelve are floating ribs, which have no front attachment to the sternum. Rib-number variations occur, but twelve pairs is the standard human anatomical pattern.