SA node is supplied by

Ans. a (Right coronary artery). (Ref. Harrison's Medicine, 18th ed/Chapter 230.)SA NODE# SA node lies at the junction of right atrium and SVC.# It measures 15 mm x 2-3 mm in size.# It is supplied by sinus node artery, which arises from right coronary (60%) or left circumflex coronary artery (40%).AV node# AV node lies at the bases of inter-atrial septum just above the tricuspid annulus and anterior to coronary sinus.# It is supplied by posterior descending coronary artery (90%).Bundle of His# Has dual blood supply (*AV nodal artery + branches of anterior descending coronary artery).