What's the purpose of the coronary arteries?

Coronary arteries: Coronary arteries run on the surface of the heart and provide blood to the heart muscle. As a contracting muscle, the heart needs a continuing supply of nutrients like oxygen, glucose, fatty acids. If coronary blood flow is slowed or interrupted, such as by a coronary narrowing or a blood clot, the heart muscle will suffer and the patient will feel chest pain or there will be a heart attack.

Feed heart muscle: In humans usually two main coronary arteries come off the aorta to feed the heart muscle. The right coronary feeds the right side of the heart and some of the muscular wall between the two sides. The left coronary divides into the left anterior descending artery and the circumflex coronary artery. The arteries bring oxygen and food to heart muscle cells.

Feed heart muscle: Coronary arteries provide fresh blood (including oxygen & nutrients) to the heart muscle itself. The heart muscle is so thick that the blood inside the heart can't penetrate the thickness of the heart muscle enough to provide adequate blood flow. Since the heart is always active, it needs a constant & large amount of blood.

Heart's supply: They supply blood to the heart muscle itself (not to be confused with the blood inside the heart's chambers which is delivered to all other organs).