coronary artery

The coronary arteries are the heart's own fuel lines. Even though gallons of blood pass through its chambers, the heart muscle cannot draw oxygen from that blood directly — it needs its own dedicated pipes, just as a fuel pump needs its own supply line even while surrounded by fuel.

These arteries arise from the aorta, just above the aortic valve, and branch out over the surface of the heart to supply the myocardium with oxygen and nutrients. There are two main coronary arteries: the right coronary artery and the left main coronary artery, which quickly divides into the left anterior descending and the circumflex branches.

Coronary arteries are central to the most common heart disease. When fatty plaque builds up inside them (atherosclerosis) and narrows or blocks the flow, the heart muscle is starved of oxygen, causing angina or a heart attack. Interestingly, the heart fills its coronary arteries mostly during diastole, when the muscle relaxes between beats.