It winds around the left side of the heart along the atrioventricular groove (coronary sulcus).

[2] The circumflex artery curves to the left around the heart within the coronary sulcus, giving rise to one or more left marginal arteries (also called 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 supplies the posterolateral left ventricle and the anterolateral papillary muscle.

This article incorporates text in the public domain from page 547 of the 20th edition of Gray's Anatomy (1918)