[Embryologic and anatomic considerations on normal and pathologic heart separation. II. Atrioventricular and interventricular septum].

The atrioventricular septum is defined and its anatomical features are described. This consists of two regions, a muscular and a membranous region. Isolated atrioventricular types of defect are described. The normal and the pathological embryogenesis of the atrioventricular septum are discussed. A definition of the interventricular septum is given and its anatomical features are described. This septum is divided into two regions, a membranous and muscular region. The muscular region is divided into three regions: inflow region or inlet, trabeculated region and outflow region or outlet. Interventricular defects are classified according to the septal regions in which they are located. The anatomical features which characterize each type of interventricular septal defect are established. A brief comment on the normal and pathological morphogenesis of the interventricular septum is made.