Inferior Border of the Heart, Lateral View

Description

Obliquely from the right lateral aspect, the inferior border (margo inferior) forms a sharp acute edge where the anterior (sternocostal) surface meets the diaphragmatic surface of the heart. The right ventricle contributes most of this margin, with the right atrium positioned superior and posterior to it and the apex of the left ventricle approaching the leftward end of the border. Along this edge, the diaphragmatic surface faces inferiorly toward the central tendon of the diaphragm, while the anterior surface turns anterosuperiorly toward the sternum and costal cartilages. Clean anatomy. This right-sided view matters when teaching how cardiac borders change with position and pathology, because a prominent acute margin can be blunted by right ventricular hypertrophy or by pericardial effusion, altering the expected contour on frontal chest radiography and at the bedside. It also supports orientation in pericardiocentesis planning, where the relationship between the diaphragmatic surface and the inferior cardiac silhouette influences the choice of subxiphoid trajectory and needle angle. The acute margin is a reliable landmark for distinguishing the sternocostal from diaphragmatic surfaces during dissection and operative exposure. Use this artwork in gross anatomy labs to reinforce surface anatomy and border terminology, or in cardiology teaching files that pair anatomic borders with CXR silhouettes and echocardiographic windows. It also fits surgical education materials covering pericardial access and the inferior pericardial reflections near the diaphragm. Anatomical accuracy verified by SciePro's Medical Advisory Board.