The heart receives its blood supply from two coronary arteries: left coronary artery and right coronary artery, which are the first arteries to branch from the aorta.
These principal arteries branch many times and finally become capillaries that supply the heart muscle. The left coronary (left main) branches into the left anterior descending artery, which supplies the anterior, or "front wall" of the left ventricle, and the circumflex, which supplies the lateral, or "side wall" of the left ventricle.The right coronary supplies the right ventricle as well as the posterior and inferior walls, or "back side," of the left ventricle.
Blood flow to the heart muscle occurs during diastole, or between contractions, when the heart muscle is resting.