Where is the SA node located?

Where is the SA node located?

• A. Crista terminalis
• B. Right atrial appendage
• C. Interatrial septum
• D. Opening of coronary sinus

Answer: (A)

The sinoatrial node is located in the right atrium at the superior end of the crista terminalis, near where the superior vena cava enters. This position places it at the boundary between the smooth posterior wall (sinus venarum) and the rough anterior atrial wall, allowing it to initiate impulses that drive the heart’s rhythm. The other structures listed do not serve as the primary pacemaker: the right atrial appendage is a muscular pouch on the atrial wall, the interatrial septum is the wall between the atria, and the opening of the coronary sinus is just a venous drainage ostium in the right atrium.

The sinoatrial node is located in the right atrium at the superior end of the crista terminalis, near where the superior vena cava enters. This position places it at the boundary between the smooth posterior wall (sinus venarum) and the rough anterior atrial wall, allowing it to initiate impulses that drive the heart’s rhythm. The other structures listed do not serve as the primary pacemaker: the right atrial appendage is a muscular pouch on the atrial wall, the interatrial septum is the wall between the atria, and the opening of the coronary sinus is just a venous drainage ostium in the right atrium.