External Contour of the Myocardium, Lateral View

Description

Seen from the left lateral aspect, the external contour of the heart is defined by the bulge of the left ventricle inferiorly and the more superior, posteriorly inclined left atrium, with the cardiac apex pointing inferolaterally. Draped over this contour, the visceral pericardium (epicardium) forms a smooth serosal surface, its mesothelium covering the underlying myocardium and continuing into the pericardial reflections around the roots of the great vessels. Along the obtuse (left) margin, epicardial fat commonly accumulates in the atrioventricular groove, softening the transition between atrium and ventricle. Clean surface anatomy. That lateral contour matters when you are correlating gross anatomy with imaging and operative views, because the left ventricle dominates the silhouette on lateral chest radiographs and contributes most of the left heart border on CT and MRI reconstructions. Pericardial and epicardial processes often announce themselves at this interface: pericardial effusion can round the cardiac margins, while inflammatory thickening from pericarditis reduces the normal gliding plane between visceral and parietal pericardium and may be appreciated as altered contour and tethering on cine sequences. Epicardial adipose over the left atrioventricular groove also complicates surgical planes during approaches to the circumflex coronary artery and mitral valve. Use this illustration in thoracic anatomy and cardiovascular modules to teach heart wall layers (endocardium, myocardium, epicardium) while keeping the learner oriented to a true lateral perspective, and in cardiology or radiology texts when introducing the concept of the cardiac silhouette and pericardial reflections. It also fits operative education materials that discuss pericardiotomy, pericardial window creation, or exposure of the left ventricular surface. Anatomical accuracy verified by SciePro's Medical Advisory Board.