Which structure forms a boundary of the triangle of Koch together with the CS ostium?

Which structure forms a boundary of the triangle of Koch together with the CS ostium?

• A. Septal leaflet of the tricuspid valve
• B. Eustachian valve
• C. The Thebesian valve
• D. Right atrial appendage

Answer: (A)

Koch's triangle is the AV nodal region in the right atrium and has three boundaries: the tendon of Todaro (superior), the ostium of the coronary sinus (posterior/base), and the septal leaflet of the tricuspid valve (anterior). The septal leaflet of the tricuspid valve forms the boundary that runs with the coronary sinus ostium to define the triangle. The Thebesian valve and Eustachian valve are not boundary structures of this triangle, and the right atrial appendage is not part of its borders.

Koch's triangle is the AV nodal region in the right atrium and has three boundaries: the tendon of Todaro (superior), the ostium of the coronary sinus (posterior/base), and the septal leaflet of the tricuspid valve (anterior). The septal leaflet of the tricuspid valve forms the boundary that runs with the coronary sinus ostium to define the triangle. The Thebesian valve and Eustachian valve are not boundary structures of this triangle, and the right atrial appendage is not part of its borders.