Which structure is located Superior to the coronary sinus ostium?

• A. SA Node
• B. Coronary sinus ostium
• C. Fossa ovalis
• D. Right atrial appendage

Answer: (C)

The key idea is understanding where these right atrial structures sit relative to each other. The coronary sinus ostium opens into the right atrium from the posterior aspect near the interatrial septum, in a region that's relatively low on the septum. The fossa ovalis sits on the interatrial septum as a shallow depression—the remnant of the foramen ovale—and it lies above the coronary sinus ostium. So, when asked which structure is located superior to the coronary sinus ostium, the fossa ovalis is the correct choice because it sits higher on the septum and marks that superior relationship.

The other options aren’t the correct superior reference: the SA node is situated high in the right atrium near the SVC entrance but isn’t specifically defined as being above the ostium, and the right atrial appendage is more anterior. The coronary sinus ostium itself isn’t a structure located above it.