Posterior Positional Representation of the Coronary Sulcus

Description

Posteriorly, the coronary sulcus (atrioventricular groove, auriculoventricular groove) encircles the heart at the junction of the atria and ventricles, forming a clear horizontal demarcation between the inferior aspects of the right and left atria superiorly and the right and left ventricles inferiorly. On the diaphragmatic surface, the groove tracks transversely, with the crux cordis located near its intersection with the posterior interventricular sulcus. The left atrium sits most posterior, while the right atrium remains more rightward, and the groove maintains its circumferential course around them. Clinically, this posterior av groove is the key surface landmark for the coronary sinus and for the atrioventricular nodal region near the crux, where the right coronary artery often gives rise to the posterior descending (posterior interventricular) artery in right-dominant circulation. Orientation at the crux matters. Inferior myocardial infarction from right coronary artery occlusion can involve the AV node and produce bradyarrhythmias or varying degrees of heart block, and surgeons use the atrioventricular groove as a guide during exposure of the coronary sinus for retrograde cardioplegia or electrophysiology procedures. Use this posterior positional representation to anchor teaching of coronary dominance patterns, the relationship of the coronary sulcus to the coronary sinus, and the surface anatomy used in interpreting catheter paths in the right atrium and coronary sinus. It also fits cleanly into cardiothoracic surgery texts and gross anatomy lab manuals that emphasize the diaphragmatic surface and crux cordis landmarks. Anatomical accuracy verified by SciePro's Medical Advisory Board.