Where is the SA node located?

The sinoatrial (SA) node is located in the upper wall of the right atrium, near the entrance of the superior vena cava. This region is crucial for heart function, as the SA node is the primary pacemaker of the heart, responsible for initiating the electrical impulses that trigger each heartbeat. These impulses spread through the atria, causing them to contract and push blood into the ventricles.

Understanding the proper location of the SA node is essential for recognizing its role in the heart's electrical conduction system. The other options do not accurately represent the anatomical position of the SA node; for example, it is not situated in the left atrium, ventricles, or interventricular septum, which are associated with different functions in the heart.