Posterior descending coronary artery arises from the right coronary artery in –% cases – Correct Answer: b) 90%
The artery which crosses the crux (junction of atrioventricular and interventricular grooves posteriorly) is called the dominant coronary artery. Posterior descending coronary artery usually arises from the dominant coronary artery. Dominance has nothing to do with the amount of myocardium supplied by the vessel – it is always the left coronary artery which supplies the maximum mass of the left ventricle. AV (atrioventricular) nodal artery arises from the dominant coronary artery. Hence the AV node is supplied by the AV nodal branch of the right coronary artery in 90% of cases.