Bone · Chest

Seventh rib

Usually the longest rib in the body — the series lengthens from the first to the seventh and shortens thereafter — and the last rib whose cartilage reaches the breastbone on its own. That makes it the lowest of the true ribs and the top of the costal margin, the sloping edge that can be traced outward and downward from the bottom of the sternum. The costal fibres of the diaphragm take origin from its cartilage along with those below it.