The right coronary artery

Does the LAD supply the SA node?

The RCA supplies the anterior and posterior walls of the RV except for the apex (supplied by the LAD), the right atrium including the SA node, the upper half of the atrial septum, the posterior third of the interventricular septum, the inferior wall of the LV, the AV node, and the posterior base of the LV.

Where does the AV node get its blood supply?

The blood supply of the AV node is from the atrioventricular nodal branch. The origin of this artery is most commonly (80-90% of hearts) a branch of the right coronary artery, with the remainder originating from the left circumflex artery. This is associated with the dominance of the coronary artery circulation.