part of part of Homo sapiens rib 9 zone of bone organ sternal end of ninth rib 2026-03-19T00:00:00Z A zone of bone organ forming the anterior extremity of the ninth rib, which connects to its costal cartilage. The costal cartilage of the ninth rib joins the costal arch formed by the cartilages of ribs seven through ten, so the ninth rib does not reach the sternum directly and is classified as a false rib. David Osumi-Sutherland