The Anatomy of the Right Coronary Artery

Arising at the aorta, the right coronary artery and its branches are major sources of blood to the right ventricle and atrium of the heart. The artery runs downward through the right atrioventricular groove that separates the right atrium and right ventricle, before curving towards the back. It splits into two major branches: the right marginal artery and the posterior descending artery, which supply the surface of the underside of the heart.

Since it plays such an important role in cardiovascular function, disorders in this vessel can lead to serious and dangerous conditions. When blood flow here is blocked, coronary artery disease, which is a leading cause of heart attack, can result. 

Anatomy

The right coronary artery emerges from the anterior ascending aorta in the left ventricle of the heart, which plays a fundamental role in the function of this organ. From there it moves down the right atrioventricular groove curving backward before bending at the crux of the heart. It then proceeds down the posterior interventricular sulcus, one of two grooves separating the ventricles, or chambers, of the heart.

The conus artery directs blood to the ventricular outflow tract, a kind of gateway for blood to access the major arteries of the heart.

The atrial branch, meanwhile, leads to the sinoatrial nodal artery, which runs behind the right atrium before encircling the superior vena cava, a vessel that delivers deoxygenated blood to the heart.

Further down the line, the right coronary artery splits into the right marginal branch and the posterior ascending artery. The right marginal branch runs down the right side of the heart and supplies the right atrium and ventricle. The posterior ascending artery, meanwhile, delivers blood to the lower portion of the heart (inferior aspect).

As the artery continues, the atrioventricular nodal artery branches off at the crux of the heart and supplies the atrioventricular node, as well as the bundle of His, both of which are associated with coordination of electrical signals in the heart.

Anatomical Variations

A number of significant variations in anatomy have been observed in the right coronary artery and its branches. The most common of these affect the posterior descending artery.

• Origin of posterior descending artery: In 70% of cases, this artery indeed arises from the right coronary artery; however, 10% of the time, this arises in a branch of the left coronary artery, and the remaining 20% display a dual origin. Furthermore, the posterior descending artery may be much smaller, meaning that other structures supply the back walls of the heart directly. It can also branch off before the crux of the heart.
• Ectopic origin: In about 1% of the cases, the right coronary artery has an ectopic, or variant, origin. Most significant is a dangerous condition called “malignant course,” which is when it arises on the left side of the heart. This may necessitate serious treatment.   
• Common origin: An even rarer case is a common origin of the left and right coronary arteries. Typically, this presents as the left circumflex and left anterior descending arteries arising from the right coronary sinus.

Function

The primary task of the right coronary artery is to ensure proper circulation to the myocardium—the muscles of the heart—and, as such, influences the overall functioning of the body.

The right coronary artery supplies blood to the right ventricle and atrium of the heart as well as sinoatrial and atrioventricular nodes. The former of these are tasked with delivering deoxygenated blood to the lungs, while the latter of these are essential in regulating heart rhythm.

Clinical Significance

The central role of this artery means that disorders and problems here can lead to drastic health effects. The most significant issue is coronary artery disease, which occurs when there's a disruption of proper blood flow to the heart’s muscles.

Atherosclerosis, or the building up of plaques in arteries, can lead to the condition, and if advanced, the vessels can harden, severely restricting blood flow. This, in turn, can damage parts of the heart and affect the amount of blood that reaches the rest of the body. In extreme cases, total blockage here can lead to a heart attack.