The breastbone or sternum.
[Greek sternon, chest.]
Several terms refer to the breastbone plus another part of the body: sternothyroid, the sternum and the thyroid cartilage; sternoclavicular, the sternum and the clavicle or collar bone; sternocleidomastoid, of muscles that connect the sternum, clavicle, and mastoid process of the temporal bone. The sternebra (plural sternebrae) is one of the four parts that fuse during development to form the body of the sternum; sternotomy (Greek -tomia, cutting) is surgical cutting of the breastbone to allow access to the heart. The adjective relating to the breastbone is sternal.