The structure indicated is the right coronary artery of the heart.

The coronary arteries arise from the aortic sinuses of the ascending aorta. The right coronary artery (RCA) arises from the right aortic sinus and the left coronary from the left aortic sinus. The right coronary artery then runs in the coronary sulcus, which separates the atria from the ventricles.

The right coronary artery gives off the following branches:

• Atrial arteries
• Right marginal branch
• Posterior interventricular branch (posterior descending artery)

The coronary artery from which the posterior descending artery arises determines the coronary dominance. The posterior descending artery may arise from the circumflex artery of the left coronary artery. Right dominant is more common than left dominant.

Learn more about the blood supply to the heart in this anatomy tutorial.