[TA] arises from superior aspect of right coronary artery as or soon after it crosses the right margin on the heart; supplies posterolateral wall (sulcus/crista terminalis portion) of right atrium. SYN: ramus atrialis intermedius arteriae coronariae dextrae [TA], lateral atrial branch of right coronary artery, marginal atrial branch of right coronary artery, right atrial branch of right coronary artery.