In the new-born foal the sternum has seven bony segments (Sternebræ),
united by persisting cartilage. The last two segments coalesce within a
few weeks after birth. In old subjects there is more or less
ossification of the intersegmental cartilage, which may lead to partial
fusion of adjacent segments, especially posteriorly. The =sternal
ligament= (Ligamentum sterni proprium internum) lies on the thoracic
surface of the sternum. It arises on the first segment, and divides
opposite the second chondro-sternal joint into three bands. The median
band passes backward and spreads out on the last segment and the xiphoid
cartilage. The lateral branches—thicker and wider—lie along the lateral
borders above the chondro-sternal joints, and end at the cartilage of
the eighth rib; they are covered by the transversus thoracis muscle.