The SA node is located at the junction of which structures?

The SA node is located at the junction of which structures?

• A. Right atrium and superior vena cava
• B. Right atrium and inferior vena cava
• C. Right atrium and coronary sinus ostium
• D. Right atrial appendage and tricuspid valve

Answer: (A)

The main idea here is where the heart’s natural pacemaker sits. The sinoatrial (SA) node is located in the wall of the right atrium at the upper part where the superior vena cava enters the atrium—that is, at the RA–SVC junction, near the crista terminalis in the anterosuperior right atrium. That’s why the correct choice points to the junction between the right atrium and the superior vena cava. The inferior vena cava enters the atrium lower down, the coronary sinus ostium is on the posterior wall where the coronary sinus drains, and the right atrial appendage and the tricuspid valve are other landmarks that do not correspond to the SA node’s location.

The main idea here is where the heart’s natural pacemaker sits. The sinoatrial (SA) node is located in the wall of the right atrium at the upper part where the superior vena cava enters the atrium—that is, at the RA–SVC junction, near the crista terminalis in the anterosuperior right atrium.

That’s why the correct choice points to the junction between the right atrium and the superior vena cava. The inferior vena cava enters the atrium lower down, the coronary sinus ostium is on the posterior wall where the coronary sinus drains, and the right atrial appendage and the tricuspid valve are other landmarks that do not correspond to the SA node’s location.