The circumflex artery of the heart is a continuation of the left coronary artery after its division from the anterior interventricular artery within the coronary groove on the upper right sternocostal surface of the heart. Just after its commencement, it may give off three separate branches:
- left atrial branch - anastomoses with left atrial branch from right coronary artery
- sinuatrial nodal artery - in the minority of the population
- left marginal artery
It continues over the left heart border within the groove, giving off multiple branches to the left ventricle and left atrium. Finally, it anastomoses with fine arterioles of the right coronary artery around the inferior margin of the left atrium.
The circumflex artery supplies the:
- left atrium
- left ventricle
- inferior surface of left ventricle
- sinuatrial node in the minority of the population
Very rarely, the circumflex artery may arise from the right aortic sinus instead of the left coronary artery.