sternum

A long flat bone in most vertebrates that is situated along the ventral midline of the thorax and articulates with the ribs. The manubrium of the sternum articulates with the clavicles in humans and certain other vertebrates.

The ventral portion of a body segment of an arthropod.

The breast-bone of man and many other vertebrates; a bone or longitudinal series of bones in the middle line of the ventral aspect of the body, chiefly in its thoracic section, completing the thoracic wall by articulation with more or fewer ribs, or elements of the scapular arch, or both: theoretically, in Owen's system, the hemal spines of a series Of vertebræ.

In arthropods, as insects and crustaceans, a median sternal or ventral sclerite of any somite of the cephalothorax, thorax, or abdomen; a sternite: the opposite of a tergite or notum.

A plate of cartilage, or a series of bony or cartilaginous plates or segments, in the median line of the pectoral skeleton of most vertebrates above fishes; the breastbone.