Sternal

Sternal is an anatomical adjective describing structures related to the sternum, the flat bone in the center of the anterior chest. The sternum, together with the ribs and clavicles, forms the anterior boundary of the thoracic cage and helps protect the mediastinal contents, including the heart and great vessels. It also provides attachment points for pectoral muscles and for costal cartilages.

Anatomy and parts: The sternum is traditionally divided into three parts—the manubrium at the top, the central body (gladiolus), and the xiphoid process at the bottom. The manubrium articulates with the clavicles at the sternoclavicular joints and with the first costal cartilage; the body articulates with the costal cartilages of ribs 2 through 7; the xiphoid process is often cartilaginous in youth and ossifies with age.

Joints and landmarks: The sternal angle (Angle of Louis) marks the junction of the manubrium and the body and lies near the level of the second rib. The first costal joint with the sternum is typically a synchondrosis, while the sternocostal joints for ribs 2–7 are primarily synovial and allow limited movement. The sternum presents a palpable sternal notch at its superior border.

Development and variation: Ossification of the sternum begins in fetal life and continues after birth, with fusion of the elements occurring in adulthood. The xiphoid process shows considerable anatomical variation in shape and cartilaginous content across individuals.

Clinical significance: The sternum is a common access point in median sternotomy for cardiac procedures and serves as an important anatomic landmark in resuscitation and thoracic procedures. It receives arterial blood mainly from perforating branches of the internal thoracic arteries and drains venously to the internal thoracic and anterior intercostal systems, with lymphatics accompanying the vessels to anterior mediastinal nodes.