The ______, also known as the breast bone, is a long flat bone that lies in the middle of the front part of the chest.
sternum
Sternum is long flat bone that lies in the middle of the frontal part of the chest. It is also knows as breast bone. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury.