Sternums

The sternum, commonly known as the breastbone, is a flat, elongated bone located along the anterior midline of the thoracic cage. It forms the central portion of the rib cage and helps protect the heart, great vessels, and other mediastinal structures.

Anatomy: It consists of three parts: the broad manubrium at the top, the body or gladiolus in the middle, and the narrow xiphoid process at the bottom. The jugular notch lies on the superior border of the manubrium, and the sternal angle (Angle of Louis) marks the junction between the manubrium and the body and corresponds roughly to the level of the second rib.

Articulations: The sternum articulates with the clavicles at the sternoclavicular joints and with the costal cartilages of ribs 1–7. Ribs 8–10 join indirectly via sharing costal cartilage, while ribs 11–12 do not attach to the sternum.

Development and variation: The sternum develops from several ossification centers and typically fuses into a single bone in early adulthood. The xiphoid process may fuse later or remain cartilaginous. Anatomic variations include a sternal foramen, a rare congenital defect, and common chest wall deformities such as pectus excavatum (sunken sternum) and pectus carinatum (pouty chest).

Clinical relevance: The sternum is a common site for surgical access to the heart and great vessels via median sternotomy. Fractures can occur from blunt chest trauma and may require imaging or intervention. Radiographs and CT scans assess sternum integrity in trauma and disease.