Circumflex branch of left coronary artery

The "LCX", or left circumflex artery (or circumflex artery, or circumflex branch of the left coronary artery) follows the left part of the coronary sulcus, running first to the left and then to the right, reaching nearly as far as the posterior longitudinal sulcus.

The circumflex artery curves to the left around the heart within the coronary sulcus, giving rise to one or more diagonal or "obtuse marginal" branches as it curves toward the posterior surface of the heart. It helps form the posterior left ventricular branch or posterolateral artery. The circumflex artery ends at the point where it joins to form to the posterior interventricular artery in ten percent of all cases, which lies in the posterior interventricular sulcus. In the other 90% of all cases the posterior interventricular artery comes out of the right coronary artery.

It gives off obtuse marginal branches (OM).

Structures Supplied
The LCX supplies the posterolateral LV and the anterolateral papillary muscle.

It also supplies the sinoatrial nodal artery in 38% of people.

It supplies 15-25% of the left ventricle in right-dominant systems. If the coronary anatomy is left-dominant, the LCX supplies 40-50% of the left ventricle. (See Coronary circulation for description of dominance.)