Question

Primary Pacemaker of the heart is situated

• A. In the wall of right atrium close to Eustachian valve
• B. On inter-atrial septum
• C. On inter-ventricular septum
• D. In the wall of left atrium close to the pulmonary veins

Answer 1

The correct option is A

In the wall of right atrium close to Eustachian valve

Primary pacemaker or the Sino-Atrial Node (SAN) is present in the right atrium lateral to the opening of the carotid sinus and at the junction of vena caval opening into right atrium (Eustachian valve is the valve of the inferior venacava).