The left main coronary artery (LMCA) normally arises from the aorta, above the left cusp of the aortic valve and just below the sino-tubular ridge. As it exits from the aortic sinus, it enters the leftward margin of the transverse sinus, being positioned between the left atrial appendage and the pulmonary trunk. It typically runs for 1 to 25 mm and then bifurcates into the left anterior descending artery (LAD) and the left circumflex artery (LCX). Its branches usually supply a larger volume of myocardium, including most of the left ventricle, the muscular ventricular septum, and the supero-lateral papillary muscle of the mitral valve, as well as giving branches to the left atrium, and in just under half the population also supplying the artery of the sinus node. In around one-quarter of the population, the LMCA also gives rise to an intermediate branch, and in rare cases to two intermediate arteries.
KeywordsLeft Anterior Descend Kawasaki Disease Marfan Syndrome Left Main Coronary Artery Pulmonary Trunk
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