The circumflex artery is one of the two main blood vessels into which the left coronary artery bifurcates. From its point of origin, it begins to descend obliquely towards the left, right below the auricle of left atrium. Then it levels off and keeps running to the left in the atrioventricular groove, giving off the left marginal branch. Extending along this narrow depression, the circumflex artery winds around towards the posterior side of heart, parallel and side by side with the great cardiac vein.
Before it reaches the middle line of heart posterior aspect, the circumflex artery gives off an important ascending branch that supplies the posterior side of left atrium and its auricle. Then it travels downwards onto the diaphragmatic surface of heart. However, it does not reach the apex of this organ.
The function of this circumflex branch of the left coronary artery is to supply a large area of the heart, which comprises the left atrium and its auricle as well as the posterior part of left ventricle.
Below, anterior view of heart, showing the point of emergence of the circumflex artery.
Posterior view of heart, exhibiting the same artery as it takes a dive downwards towards the apex.
