A sternotomy is a procedure that is performed to begin open-heart surgery. The sternum (or breastbone) lies vertically in the chest and connects to the collar bones and cartilaginous portions of the ribs. A sternotomy is performed to gain access to the heart inside the chest cavity. An incision is made along the center of the chest. The sternum (breastbone) is then divided vertically and the rib cage is spread open (see fig. 2). This allows access to the heart which lies just below the sternum. Following the procedure the rib cage is closed and the sternum halves are fixed together in their original position.

Figure 1: Location of the heart in the chest.

Figure 2: Location of incision and division of the sternum.