The human rib cage is composed of 12 pairs of ribs. “Costal” refers to ribs. Intercostal muscles between the ribs facilitate breathing. The ribs articulate with the 12 thoracic vertebrae on the posterior side of the body (costovertebral joints). And they connect with the sternum (via the costal cartilage) on the anterior side (these are called costochondral joints). Ribs 1-7 are “true ribs” and ribs 8-12 are “false ribs“. Ribs 11 & 12 are “floating ribs“, and are an area of caution. The head and neck of each rib is on the posterior side of the body.