Left main coronary artery

The left main coronary artery (LMCA) arises from the left coronary sinus of the aorta and serves as the primary source of blood supply to the majority of the left ventricle. After its origin, the LMCA courses between the pulmonary artery and the left atrial appendage, running for a variable length (commonly 5–15 mm, but can range from 2 mm to over 20 mm) before bifurcating into the left anterior descending (LAD) artery and the left circumflex (LCx) artery. In some cases, a trifurcation occurs, with a third branch known as the ramus intermedius or intermediate branch.