sternum

Large flat bone, 15–20 cm/5.9–7.8 in long in the adult, at the front of the chest, joined to the ribs. It gives protection to the heart and lungs. During open-heart surgery the sternum must be split to give access to the thorax.

The sternum can be felt beneath the skin throughout its whole length, from the root of the neck into the abdominal wall. It has three parts – the manubrium, body, and xiphoid process – which are united by cartilage. The joint between the manubrium and body, the sternal angle, can be felt opposite the second ribs.