Because your heart must operate continuously to supply the rest of your body with blood, it works harder and requires a richer blood supply of its own than any other muscle in your body. It cannot extract oxygen and nutrients from the blood that moves through it, so it maintains its own dedicated circulatory system of arteries and veins. This coronary circulation begins with two coronary arteries that branch off of the aorta just above the aortic valve (on the left side). These arteries extend over the surface of the heart and branch into smaller vessels that pene- trate the heart muscles to provide oxygen. After the muscles of the heart have been nourished, the blood travels through coronary veins into the coronary sinus and then the right atrium. At this point, it ?ows in with the oxygen-depleted blood from the rest of the body.
The left coronary artery supplies blood to most of the powerful left ventricle. The circum?ex coronary artery is really a branch of the left coronary artery. It wraps around the back of the heart and has several smaller branches. The right coronary artery supplies part of the left ventricle and most of the right ventricle. Interestingly, the con?gura- tion and even the sizes of the coronary arteries differ signi?cantly from person to person.
The coronary arteries deliver oxygen-rich blood to the cardiac mus- cle cells according to the demand at the moment. If you are exerting yourself physically, your heart beats faster and more vigorously, and your coronary arteries expand to allow greater blood ?ow.