Like the rest of your body, your heart needs a continuous supply of oxygen. The coronary arteries carry oxygen-rich blood to the heart muscle.
As blood leaves the left ventricle, it begins its journey into your body through the aorta. At the beginning of the aorta, near the top of the heart, two arteries branch off and go directly to the heart muscle. These are the “left” and “right” coronary arteries.
The first part of the left coronary artery is the left main artery. It is the width of a straw and less than an inch long. The left main artery divides into the left anterior descending artery, which goes down the side of the heart, and the left circumflex, which surrounds the left side and then toward the back of the heart.
The right coronary artery comes from the aorta, circulates around the right side and then to the back of your heart.
The coronary arteries are on the surface of your heart and gradually divide into smaller branches. These penetrate deep into the heart muscle and carry oxygen-rich blood to the cells.