Which of the following coronary arteries does not perfuse the SA node in 55% of the population? Left Circumflex Right Coronary Artery Right Marginal Branch Left Anterior Descending

The correct answer is: Left Circumflex.<br /><br />In approximately 55% of the population, the SA node is perfused by the Right Coronary Artery (RCA) rather than the Left Circumflex artery. The RCA typically supplies blood to the SA node, which is responsible for initiating the heartbeat. The other options, such as the Right Marginal Branch and the Left Anterior Descending artery, are less commonly involved in perfusing the SA node compared to the RCA.