The left main coronary artery supplies blood to the left side of the heart muscle (the left ventricle and left atrium). The left main coronary divides into branches: The left anterior descending artery, which branches off the left coronary artery and supplies blood to the front of the left side of the heart.The circumflex artery, which branches off the left coronary artery and encircles the heart muscle. This artery supplies blood to the outer side and back of the heart.Right coronary artery (RCA). The right coronary artery supplies blood to the right ventricle, the right atrium, and the SA (sinoatrial) and AV (atrioventricular) nodes, which regular the heart rhythm.The right coronary artery divides into smaller branches, including the right posterior descending artery and the acute marginal artery.he left main coronary divides into branches: The left anterior descending artery, which branches off the left coronary artery and supplies blood to the front of the left side of the heart.