bundle branch [Dan, bondel + Fr, branche] , a segment of the network of specialized conducting fibers that transmits electrical impulses within the ventricles of the heart. Bundle branches are a continuation of the atrioventricular (AV) bundle, which extends from the upper part of the intraventricular septum. The AV bundle divides into a left and a right branch, each going to its respective ventricle by passing down the septum and beneath the endocardium. Within the ventricles the bundle branches subdivide and terminate in the Purkinje fibers.
