The sternum is located in the anterior wall of the thorax just below the skin and can be easily felt under the skin. The shape of the sternum is a long flat bone with a wide top and narrow bottom. It is connected to the clavicle and the seven pairs of superior rib cartilage on the upper side and both sides, respectively. The sternum is divided from top to bottom into three parts: the sternal stalk, the sternal body, and the saber process. The sternum is composed of the ribs and the posterior spine, which forms the thoracic cavity and mainly serves to protect the heart, lungs and mediastinal organs. Clinical applications of the sternum: First, it is used to perform bone puncture and extract bone marrow fluid for examination; second, sternal fractures are relatively common. Sternal fractures are not dangerous in themselves, but they are often combined with multiple rib fractures, or contusions of large blood vessels and lung injuries. If such serious organ damage occurs, it can easily lead to respiratory and circulatory dysfunction, which can be life-threatening in serious cases.