<prompt> SA node blood supply is -Rt. coronaryLt. coronaryLt. and descendingAnt aortic sinus  <response>: Ans. is a i.e., Rt. coronary o SA node is supplied by right coronary artery in 65 of population and by left coronary artery in remaining 35.o Left coronary artery suppliesi Most of left atrium.ii Most of the left ventricle except the area adjoining posterior interventricular groove and small part of right ventricle adjoining anterior interventricular groove.iii Anterior 23 of ventricular septum.iv Right bundle branch, left bundle branch and in 35 of cases SA node.o Right coronary artery suppliesi Right atrium, and a part of left atrium.ii Most of the right ventricle except the area adjoining the anterior interventricular groove and small part of left ventricle adjoining posterior interventricular groove.iii Posterior 13 of interventricular septum.iv Whole conducting system except right bundle branch and a part of left branch of AV bundle.v SA node in 65. 