The [circumflex artery]  (CFX) is one of the two branches of the left coronary artery, the other one being the left anterior descending artery (LAD), also known as the anterior interventricular artery.

The prefix [circum-] means "around", while the root term [-flex-] means "to bend". This describes quite well the circumflex artery, which "bends around" the obtuse margin of the heart passing from the anterior surface to the posterior surface of the heart.

The circumflex artery lies deep to the epicardium in the subepicardial fatty layer. It gives off several branches, including small left atrial branches and one or two obtuse marginal arteries (OM1 and OM2)that provide blood supply to the left ventricle in its obtuse margin and posterior ventricular region, as well as a portion of the anterior papillary muscle related to the mitral valve.

Image property of: CAA.Inc.. Artist: Victoria G. Ratcliffe