The<unk>  (abbreviated<unk>  node or<unk> , also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the heart, and thus the generator of sinus rhythm. It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. These cells are modified cardiac myocytes. They possess some contractile filaments, though they do not contract.
Sinoatrial node
Atrioventricular node
Atrioventricular nodal branch
Interventricular septum
Bundle of Kent
Interatrial septum
Atrioventricular canal
Tricuspid valve