The structure and position of the sternum. The sternum is part of the thoracic skeleton. It is located in the upper part of the midline of the anterior chest and is long, narrow, and flat. The sternum is composed of three parts: the upper sternum, the body sternum, and the xiphoid process. The upper sternum is connected to the clavicle, and the sternum and xiphoid process of the body are merged into one body. The sternum is the central axis of the human body and forms the thoracic structure with the spine. Function of the sternum The sternum is an important scaffold for the respiratory system, cardiovascular system, and digestive system, and is a key bone of the respiratory and circulatory systems. The thorax, which is composed of the sternum, ribs, and spine, can protect and support the heart, lungs, spine, and food.