Conduction of the Heart (3)

Bundle Branches
The left bundle branch arises as a series of radiations, or fascicles, at right angles to the bundle of HIS. A superior, anterior fascicle courses down the anterior aspect of the interventricular septum to the anterolateral papillary muscle, where it breaks up into a Purkinje network. The inferior, posterior fascicle is shorter and thicker, passing posteriorly to the base of the posteromedial papillary muscle, where ti branches into the Purkinje network. Purkine fibers to the interventricular septum may arise as a separate radiation or as tibers from either the anterior or posterior fascicles.

The right bundle branch courses down the interventricular septum on the right side. It contributes Purkinje fibers to the septum only near the apex of the right ventricle. At the lower end of the septum, it passes into the right ventricular wall, where it branches into a Purkinje network.