Where is the AV node located?

• A. RA-LA septum, Triangle of Koch
• B. Interventricular septum
• C. Right atrial appendage
• D. Left atrium

Answer: (A)

The AV node sits in the right atrium on the lower part of the interatrial septum, specifically at the apex of the triangle of Koch. This triangle is a defined region bounded by the tricuspid valve, the opening of the coronary sinus, and the tendon of Todaro; the AV node lies within this area near the septal surface, just above the membranous part of the interventricular septum. This location is why the option identifying the triangle of Koch on the right atrial septum best describes where the AV node resides. The other choices point to areas not housing the AV node: the interventricular septum is downstream of it where the His bundle travels; the right atrial appendage and the left atrium are not the AV node’s location.