The Cranial cavity is the space formed inside the rib cage.
 This happens through one of two actions (or a mix of the two): when the lower ribs the diaphragm connects to are stabilized by muscles and the central tendon is mobile, when the muscle contracts the central tendon is drawn down, compressing the cavity underneath and expanding the thoracic cavity downward
 At the front of the body, most of the ribs are joined by costal cartilage to the sternum

