The sternum, often called the breastbone, is a flat bone positioned at the center of the chest. It forms part of the rib cage and protects organs within the chest.
Locating Your Sternum
To locate your sternum, place your fingers in the middle of your chest. You will feel a flat, vertical bone running down the center. The top of the sternum, known as the manubrium, can be felt just below the notch at the base of your throat, between your collarbones.
Moving downwards, you will feel the main body of the sternum, which is the longest part. At the very bottom, you might feel a small, pointed projection, which is the xiphoid process.
Anatomy and Function of the Sternum
The sternum consists of three parts: the manubrium, the body, and the xiphoid process. The manubrium is the broad, upper section, connecting to the collarbones and the first pair of ribs. The body is the central, longest part, to which the third through seventh pairs of ribs attach via cartilage. The xiphoid process is the smallest, lowest part, primarily cartilage in younger individuals and ossifying with age.
Along with the ribs, the sternum forms the rib cage, safeguarding vital organs such as the heart, lungs, and major blood vessels. Beyond protection, the sternum contributes to the mechanics of breathing. Cartilage connecting the sternum to the ribs allows minor movements with each breath, facilitating thoracic cavity expansion and contraction. The xiphoid process also serves as an attachment site for the diaphragm, a key muscle for breathing, and muscles of the abdominal wall.
Common Conditions Related to the Sternum
Pain in the sternum can arise from various conditions, with costochondritis being a common cause. Costochondritis involves inflammation of the cartilage connecting ribs to the sternum, causing sharp chest pain that may worsen with movement or deep breaths. Muscle strains and injuries to the collarbone or the sternoclavicular joint (where the collarbone meets the sternum) can also cause discomfort. Additionally, conditions like acid reflux can cause pain behind the sternum, which can be mistaken for sternum pain.
The sternum is also significant in certain medical procedures. During cardiopulmonary resuscitation (CPR), chest compressions are applied to the lower half of the sternum to circulate blood to vital organs. While effective compressions require significant force, which can sometimes lead to sternum or rib fractures, the life-saving potential of CPR outweighs this risk. Furthermore, the sternum can be a site for bone marrow biopsies, where a needle is inserted to collect a sample for diagnosis. This procedure helps diagnose blood diseases and assess bone marrow health.