The right coronary artery (RCA) supplies the atrioventricular (AV) node in approximately 85–90% of individuals (right dominant circulation). The AV nodal artery arises from the RCA at which anatomical landmark?

• A Right atrioventricular groove at the acute margin
• B Posterior wall of the right ventricle near the diaphragmatic surface
• C Proximal RCA just after the right sinus of Valsalva
• D Crux of the heart (posterior interventricular groove where the two AV grooves meet) ✓

Explanation

In right-dominant circulation, the AV nodal artery arises from the RCA at the crux of the heart — the posterior point where the posterior interventricular groove meets the atrioventricular groove. This 'U-turn' of the RCA (the posterior descending artery origin) gives off the AV nodal artery, which supplies the AV node and bundle of His proximally. This explains why inferior myocardial infarctions (RCA territory) cause AV block. In left-dominant circulation (~15%), the LCx crosses the crux and gives the AV nodal artery.

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

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Written and medically reviewed by the StethoPrep medical team.