Sternal Angle Of The Sternum, Anatomy

Description

Sternal angle (Angle of Louis) forms a palpable transverse ridge at the manubriosternal joint, where the manubrium meets the sternal body (gladiolus) on the anterior midline of the thorax. The manubrium sits superiorly and slightly posterior to the body of the sternum, creating the step-off that defines this landmark. Costal notches along the lateral margins align with the second costal cartilages, while the jugular notch lies superior and the xiphoid process would be inferior to the sternal body outside the immediate emphasis of this region. Bone contours and articular margins are presented as a fixed anterior surface landmark. Clinically, the sternal angle is the reference point for identifying the second rib, which anchors rib counting during chest examination, intercostal space selection for thoracentesis, and surface localization of auscultation points. It also corresponds to the transverse thoracic plane at approximately the T4 to T5 intervertebral level, a teaching staple for mediastinal anatomy because it approximates the tracheal bifurcation (carina), the beginning and end of the aortic arch, and the boundary between superior and inferior mediastina. A hard landmark. The emphasis on the manubriosternal articulation helps clarify why the ridge remains palpable even when soft tissue obscures adjacent costal cartilages. Use this illustration in gross anatomy labs to orient students to thoracic surface anatomy, in radiology and physical diagnosis materials to support rib and mediastinal level localization, and in surgical or critical care references when discussing safe sternal landmarks for midline approaches and chest compressions relative to the xiphoid process. Anatomical accuracy verified by SciePro's Medical Advisory Board.