question_answer

SA node is located in :    

A)  lower lateral wall of right atrium

B)  upper lateral wall of right atrium

C)  upper lateral wall of left atrium

D)  lower kitcral wall of left atrium

Correct Answer: B

Solution :

SA node (sinoatrial node, pacemaker) is located in upper lateral wall of right atrium. The contraction of atria is initiated and activated by SA node which spreads wave of contraction across the walls of atria via muscle fibres  at  regular  intervals.  AV node (Atrio-ventricular node-pace setter) is localled in lower lateral wall of right atrium. The wave of contraction originated by SA node are transmitted to all parts of ventricallyvia bundle of His and Purkinjes fibres by AV node.