Figure 4

The view of the opened right atrioventricular junction (A) shows a muscular ventricular septal defect opening to the inlet of the right ventricle beneath the septal leaflet of the tricuspid valve. In the specimen shown in Figure 4B, the free wall of the right ventricle has been lifted away to show a muscular ventricular septal defect opening into the outlet portion of the right ventricle. The ventricular septal defect lies within the arms of the septal band (red Y), with the caudal arm fusing with the inner heart curvature to produce a muscular bar (yellow dots) that interposes between the leaflets of the atrioventricular and arterial valves.