Between the two upper chambers lies the thin wall called the

Between the two upper chambers lies the thin wall called the

• A. interatrial septum
• B. interventricular septum
• C. atrial septum
• D. coronary groove

Answer: (A)

Between the two upper chambers the thin wall is the interatrial septum. It separates the right atrium from the left atrium, keeping the atria as distinct chambers. The wall between the ventricles is the interventricular septum, which is much thicker because it must withstand higher pressures during pumping. The term atrial septum can be used, but the precise name for the wall between the atria is interatrial septum. The coronary groove is a surface groove containing vessels, not a separating wall.