Sternum

(stür'num.) (Anat.) The os pectoris, or breast-bone, a bone which composes the fore-part of the breast, and into which the ribs are fitted. It forms the front of the human chest from the neck to the stomach. The S. is wanting in fishes, amphibians, and ophidians. In birds it is largely developed, and has a projecting keel. [s. 857]