The coronary arteries branch off the aorta near the point where it emerges from the heart.

The right coronary artery (RCA) supplies blood to the right atrium, right ventricle, sinoatrial node, and atrioventricular node.

The left coronary artery (LCA) immediately divides into the left circumflex artery (LCX) and left anterior descending artery (LAD). These supply blood to the left atrium and left ventricle.

Most myocardial infarctions occur in the left anterior descending artery, which is confusingly called the anterior interventricular artery by many authorities.

The posterior cardiac vein and middle cardiac vein drain the posterior side of the heart, while the anterior cardiac veins and great cardiac vein drain the anterior surface. Note that the great cardiac vein parallels the left anterior descending artery (anterior interventricular artery).

All the venous drainage gathers together at the coronary sinus, which in turn dumps its contents directly into the right atrium. Remember that the sinoatrial node gets its name from its position near the coronary sinus and the wall of the right atrium.