Triangle Of  Koch :

Its a Triangular area located in right Atrium. Which indicates the position of AV node. Its named after the German pathologist and cardiologist Walter Karl Koch, is an anatomical area located in the superficial paraseptal endocardium of the right atrium, Its boundaries are the coronary sinus orifice, tendon of Todaro, and septal leaflet of the right atrioventricular valve

Borders : 

1) Septal leaflet of Tricuspid Valve.

2) Anteromedial margin of Coronary Sinus. &

3) Subendocardial tendon of Todaro.