has part has part occurs in characteristic of has modifier ossification Abnormal sternum morphology Abnormal enchondral ossification Abnormal sternal ossification The sternum develops from two cartilaginous bars, situated one on either side of the median plane and connected with the cartilages of the upper nine ribs of its own side. During development, the two cartilaginous bars fuse with each other to form the cartilaginous sternum. This in turn is ossified from six centers: one in the manubrium, four in the body of the sternum, and one in the xiphoid process. quality abnormal sternum