Bone · Chest

Fourth rib

A typical mid-thoracic rib, and the one at which the cage's downward slope becomes obvious: from here down each shaft runs so obliquely that its front end lies a full vertebral level below its back end. Its head carries two facets, meeting the bodies of the third and fourth thoracic vertebrae and the disc between them, while its tubercle meets the transverse process of the fourth. Its cartilage still reaches the breastbone directly, so it remains a true rib.