Left Marginal Branch of the Circumflex Artery

Description

Oriented from the inferior aspect, the left coronary artery is followed into its circumflex branch (ramus circumflexus), which courses within the left atrioventricular (coronary) sulcus beneath the left atrial appendage toward the obtuse margin. From that parent vessel, the left marginal branch (often termed the obtuse marginal artery) descends along the left border of the heart toward the apex, running superficial to the left ventricular myocardium and giving off smaller epicardial arterioles. Adjacent blue vessels track the accompanying cardiac veins, with tributaries converging toward the coronary sinus in the posterior atrioventricular groove. Clear surface anatomy is maintained. This inferior perspective helps you teach coronary dominance and territory, because the circumflex system supplies the lateral and posterolateral left ventricle and, in left-dominant hearts, continues to the posterior interventricular sulcus as the posterior descending artery. Ischemia in an obtuse marginal branch commonly produces lateral wall infarction patterns (I, aVL, V5 to V6), and these vessels are frequent targets for coronary angiography and bypass grafting with saphenous vein or radial artery conduits. The relationship to the atrioventricular groove and coronary sinus also matters during mitral valve surgery and left atrial procedures, where epicardial vessels remain at risk from traction or suture placement. A practical landmark. Use this rendering for undergraduate and graduate gross anatomy labs, cardiology lectures on coronary circulation, and figure plates in interventional cardiology or cardiothoracic surgery texts that need a clean depiction of the circumflex and marginal branches from below. It also fits well in patient-facing materials explaining lateral wall myocardial infarction and revascularization planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.