A small mass of specialized cardiac muscle fibers, located in the wall of the right atrium of the heart, that receives heartbeat impulses from the sinoatrial node and directs them to the walls of the ventricles. Also called AV node房室结：一小块特化心肌纤维组织，位于右心房壁，接受窦房结传来的心跳冲动并将其传送到心室壁 也作 AV node