attaches_to constitutional_part_of regional_part_of Membranous part of cardiac septum Heart Right atrium Left ventricle Membranous part of interventricular septum Atrioventricular septum FMA:7136 Membranous atrioventricular septum Region of membranous part of interventricular septum which is continuous with the membranous part of interventricular septum proper and is attached to the septal leaflet of tricuspid valve and the right posterior cusp of the aortic valve. fma Septal leaflet of tricuspid valve Right posterior cusp of aortic valve Region of membranous part of interventricular septum