Coronary Arteries: Anatomy and Function

Coronary artery anatomy is designed to ensure the heart gets enough of the oxygen-rich blood it needs to function.

The coronary arteries supply blood to the myocardium (heart muscle). Because it must work continuously (as opposed to other muscles of the body, which are often at rest), the heart muscle has a very high requirement for oxygen and nutrients and therefore requires a very reliable, continuous supply of blood.

This article will go over the anatomy of the coronary arteries. You will also learn about the coronary artery's blood supply and how it helps the heart keep pumping.

Why Are The Coronary Arteries Important?

The coronary arteries have a very important job. If they aren't able to keep blood going to and from the heart, it can have serious—even deadly—consequences.

If the blood flow through the coronary arteries becomes partially blocked, the heart muscle may become ischemic (oxygen-starved), a condition that often produces angina and a drop-off in muscle function (manifested by weakness and dyspnea). If the blood flow becomes completely blocked, the heart muscle supplied by the blocked coronary artery can suffer infarction or cell death. This is called a myocardial infarction, or heart attack.​

The significance of the damage done to the heart muscle during a heart attack depends not only on which coronary artery is affected but also on the location of the blockage within the artery. A blockage close to the take-off of the coronary artery will likely do far more damage than a blockage further down the artery, or in one of its small branches. If a heart attack occurs, permanent damage can often be prevented by getting immediate medical attention, as several strategies are available for quickly opening a blocked coronary artery.​

Anatomy of the Coronary Arteries 

The two major coronary arteries are the right coronary artery (RCA) and the left main (LM) coronary artery. The coronary arteries arise from the aorta (the body’s main artery) just beyond the heart’s aortic valve.

Left Coronary Artery

As its name suggests, the left coronary artery supplies blood to the left side of the heart.

It quickly branches into two large arteries: the left anterior descending artery (LAD) and the circumflex artery (Cx). The heart muscle itself is supplied by one of these three major coronary arteries: the LAD, the Cx, and the right coronary artery (RCA).

The picture above shows the RCA and the LAD arteries. The Cx artery is depicted by a ghost-like shadow behind the heart.

Right Coronary Artery

The right coronary artery (RCA) and its branches supply blood to most of the right atrium, right ventricle, the sinus node, and (in most people) the AV node. The RCA is shown on the left side of the figure, coursing around the edge of the heart.

Right Posterior Descending Artery

The long segment of the RCA that, in this picture, goes to the very tip of the heart (the apex) is called the right posterior descending artery (PDA).

In most people (about 75%), the PDA comes off the RCA, as in this picture. This is called “right dominant.” However, in 25%, the PDA arises from the Cx artery, which is called “left dominant.”

This distinction is important, since, for example, a heart attack arising from a blockage in the RCA in a right dominant heart will do more damage than it would in a left dominant heart.

Left Anterior Descending Artery

Returning to the picture, the LAD and its many branches are shown coursing down toward the apex from the top of the heart. The LAD supplies the left atrium and major portions of the left ventricle—the heart’s major pumping chamber.

A heart attack arising from a blockage in the LAD almost always does serious damage. Coronary artery plaques in the LAD are often referred to by cardiologists as “widow makers.”

Summary

The anatomy of the coronary arteries ensures enough blood gets to and from the heart. If the heart muscle is not getting enough blood, it will be starved of the oxygen it needs to work. If a coronary artery's blood supply is blocked, it can lead to a heart attack.