The sternum, commonly known as the breast bone, is a long, flat bone situated vertically at the center of the chest, just beneath the skin and muscles. It acts as the primary anchor point for the rib cage, forming the central axis that stabilizes the entire thoracic skeleton. The breast bone is relatively flat and narrow, with a shape often compared to a sword or a necktie.
Identifying the Three Main Sections
The breast bone is comprised of three distinct segments. The uppermost section is the manubrium, which has a broad, roughly quadrangular shape and can be felt at the top of the chest. The manubrium is where the collarbones (clavicles) articulate with the sternum, forming the only direct skeletal connection between the arm and the central trunk of the body.
Below the manubrium is the body of the sternum, which is the longest and largest segment, extending down the central chest. The junction between the manubrium and the body forms a slight ridge that is often called the sternal angle, which is an important anatomical landmark. This angle is used to locate the attachment point of the second set of ribs.
The lowest portion is the xiphoid process, a small, pointed tip. This segment is typically made of cartilage in younger individuals and gradually ossifies (turns into bone) as a person ages, often completing this process around age 40.
What the Breast Bone Does
The primary function of the breast bone is protection for the internal structures of the chest. Along with the rib cage, it forms a protective cage around the heart, the lungs, and the great vessels, safeguarding them from external trauma. The thymus gland, an organ important to the immune system, also sits directly behind the upper portion of this bone.
Beyond protection, the sternum is a significant point of connection for the musculoskeletal system. It provides an attachment site for the costal cartilages, which link the first seven pairs of true ribs directly to the central skeletal frame. This connection allows for the minor movements necessary for the chest cavity to expand and contract during respiration. Several muscles in the chest and upper abdomen also attach to the sternum, helping to stabilize the torso.
Common Sources of Pain in the Area
One of the most frequent causes of discomfort near the breast bone is costochondritis, which involves inflammation of the cartilage that connects the ribs to the sternum. This condition typically presents as sharp or aching pain that can worsen with deep breaths, coughing, or when pressure is applied to the area. Costochondritis is a common source of non-cardiac chest pain and is generally a self-limiting issue.
In cases of significant blunt trauma, such as from a car accident, a sternal fracture may occur, causing acute and intense pain in the area. These fractures require medical attention and are far less common than rib fractures. Discomfort in the sternum region can also arise from issues not directly involving the bone, such as muscle strain from intense exercise or severe coughing fits.
Referred pain from other systems, like gastroesophageal reflux disease (GERD) or pleurisy, can also be perceived as sternal pain due to the proximity of these organs. It is important to have any persistent chest pain evaluated by a healthcare professional to rule out more serious causes, such as a heart issue.