The sternum (breastbone) located in the anterior midline of the body is a flat bone approximately 15 cm long consisting of three regions.   The manubrium (the superior portion) articulates with the clavicles laterally and with the first two pairs of ribs.  The  body (which forms the bulk of the sternum)  bears notches that articulate with the costal cartilages of the third to seventh pairs of ribs.  At the inferior end of the sternum is the small, variably-shaped xiphoid process, which although formed of hyaline cartilage in youth,  is usually ossified in adults.