The rib cage includes the ribs, the 12 thoracic vertebrae (spine), and sternum (breastbone).
The ribs are connected to the vertebrae in back and all but four ribs (the lowest two pairs) are connected to the sternum in front by cartilage. The small spearlike structure at the bottom of the sternum is the xiphoid process.
Damage to the rib cage can interfere with breathing since the movement of the rib cage assists in inhalation and exhalation. (See Subcourse MD0532, Cardiopulmonary Resuscitation, for additional information on the mechanics of respiration.)