Normal Anatomy of the Human Cardiac Conduction System

The conduction system of the human heart is made up of a number of major muscular components. The sinus node, the normal pacemaker, is situated at the junction of the superior vena cava with the right atrium. The atrioventricular (AV) node is located in the lower part of the right atrium on the fibrous atrioventricular ring. The common AV bundle (His bundle), which connects atrial and ventricular musculature, is located in the right fibrous trigone and the inferior portion of the membranous septum. The compact right bundle branch and the broad left bundle branch originate from the His bundle and pass down the ventricular septum toward the apex. Purkinje system usually refers to the bundle branches. Mahaims paraspecific fibers are small fascicles that appear to connect the His bundle with the subjacent ventricular myocardium. Atrial conduction pathways while anatomically difficult to demonstrate, connect the sinus and AV nodes.