Location:
The circumflex artery branches off of the left coronary artery and supplies most of the left atrium: the posterior and lateral free walls of the left ventricle, and part of the anterior papillary muscle. The circumflex artery may give off a variable number of left marginal branches to supply the left ventricle. The terminal branch is usually the largest of these branches. More likely, the circumflex artery may continue through the AV sulcus to supply the posterior wall of the left ventricle and (with the right coronary artery) the posterior papillary muscle of the bicuspid valve. The left circumflex branches decrease in diameter along their lengths.

Function:
In 40-50% of hearts the circumflex artery supplies the artery to the SA node.