The arteries that feed the heart muscle
The heart supplies itself through the coronary arteries, which branch from the aorta just above the aortic valve. The left main coronary artery quickly divides into the left anterior descending (LAD), which serves the front of the heart and much of the septum, and the left circumflex (LCx), which wraps around the left side. The right coronary artery (RCA) supplies the right side and, in most people, the inferior wall and parts of the conduction system.
Which artery dominates the back of the heart varies between individuals, described as right or left coronary dominance.
Why timing of coronary flow is unusual
Unlike most of the body, the heart muscle receives most of its blood flow during diastole, the relaxation phase, rather than systole. During contraction, the squeezing myocardium compresses the vessels running through it, especially on the left side, briefly choking off flow. Only when the muscle relaxes can blood perfuse the wall freely.
This is why very fast heart rates, which shorten diastole, can limit coronary perfusion. This is general educational anatomy and physiology, not medical advice; consult a qualified clinician for any cardiac concern.