- a small mass of muscular fibers at the base of the wall between the atria, conducting impulses received from the sinoatrial node by way of the atrioventricular bundles and, under certain conditions, functioning for the sinoatrial node as pacemaker of the heart. Abbreviation: A-V node.
- A small mass of specialized cardiac muscle fibers, located near the ostium of the coronary sinus and giving rise to the atrioventricular bundle of the conduction system of the heart.A-V node
- A small area of specialized cardiac muscle cells that conducts impulses from the sinoatrial node to the ventricles and initiates the contraction of the ventricles. It is located in the right atrium.