An early atrial branch passes in the groove between the right auricle and ascending aorta, and gives off the sinu-atrial nodal branch (Fig. 3.78A), which passes posteriorly around the superior vena cava to supply the sinu-atrial node.
A right marginal branch is given off as the right coronary artery approaches the inferior (acute) margin of the heart (Fig. 3.78A,B) and continues along this border toward the apex of the heart.