Purkinje fibers

Bundle of His moves away from atrioventricular (AV) node, penetrates the stroma of the heart, goes forward and crosses the membranous part of the interventricular septum. In the muscular part of the interventricular septum, bundle of His divides into a wide left branch and narrow right branch. Their branches extend along the endocardium of the ventricles, and the terminal branches (Purkinje fibers) depart from them deep into the myocardium.