The coronary arteries are the arteries that supplies blood to the heart. They are the first artery to branch off from the aorta and is are some of the largest arteries in the body. Although the heart is full of blood, the blood in the chambers of the heart is not used to oxygenate the muscles of the heart. The heart, like all other muscles in the body, is supplied with blood from capillaries, which branch off from the coronary artery. An infarction of a coronary artery will result in a heart attack. This can be the result of clotting or fatty plaque.