Anatomy Physiology

Although the heart is the critical organ involved in the circulation of blood throughout the body, the heart muscle itself relies upon two relatively small arteries to supply its demand for oxygen and nutrients. This article will provide an overview of the heart’s own blood supply, the coronary arteries.

The main pumping chamber of the heart is the Left Ventricle (LV). The Aorta is the body’s largest and most critical artery and is a direct extension of the LV. The LV and aorta are separated by the Aortic Valve, which ensures that blood flow is always directed away from the heart and into the Aorta.

If you were looking down at the heart from above you would notice that two arteries arise (“come off of”) from the Aorta’s left and right sides and just above the Aortic Valve. These are named the Left Main and the Right Coronary Arteries, respectively. We will consider the left-sided Coronary Artery first.

The Left Main Coronary Artery is rarely more than 5 to 7 millimeters in length. It soon divides (“bifurcates”) into the Left Anterior Descending Coronary Artery and the Circumflex Coronary Artery. Since we will be discussing only the Coronary Arteries from this point forward, we will drop the “Coronary Artery” portion of the arteries names unless otherwise noted.

The Left Anterior Descending (LAD) is located on the “left” side of the heart, on its “anterior” (front) wall, and then runs “downward” (descends) as it gives off progressively smaller branches with each branch eventually ending in a “bed” of microscopic-size capillaries. The LAD and its branches feed the anterior and apical (lower) walls of the Left Ventricle.

The other artery arising from the Left Main is the Circumflex (Cx) Coronary Artery. The CX runs in the opposite direction as the LAD, meaning that it runs to the posterior (“back”) and lateral (“outside”) walls of the heart. As does the LAD, the Cx also gives off progressively smaller arteries that terminate (“end”) in capillaries. The Cx feeds the back and “outside” walls of the Left Ventricle.

The Right Coronary Artery (RCA) arises from the right side of the Aorta and then travels to the right (“medial”) along the portion of the heart that is closest to the diaphragm (the “inferior” wall). As is the case with any other artery, the RCA gives off branches that eventually become capillaries. Of particular interest is the notion that the RCA provides blood flow to the heart’s innate electrical system, or “natural pacemaker.” As a consequence, any reduction in blood flow within the RCA can cause changes in both the heart’s rate and rhythm.

Admittedly, this overview of the coronary circulation is superficial. Those wishing to know more about this topic are encouraged to view other related articles posted on this site or to consult additional online resources.