The sinoatrial node lies in the wall of the right atrium near the opening of the superior vena cava. Its arterial supply most commonly arises from:

• A Left anterior descending artery in the majority
• B Right coronary artery in all individuals
• C Posterior descending artery in the majority
• D Right coronary artery in 60% and left circumflex artery in 40% of individuals ✓

Explanation

The SA node artery (sinus node artery) arises from the right coronary artery in approximately 55–60% of individuals and from the left circumflex artery in approximately 40–45%. This dual supply pattern explains why SA node dysfunction can result from occlusion of either vessel. The posterior descending artery supplies the AV node; its territory depends on coronary dominance. This distinction is relevant for understanding which infarct patterns cause SA node dysfunction versus AV block.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.