pars membranacea septi (heart, anatomy)

Last reviewed 01/2018

The pars membranacea septi is part of the fibrous skeleton of the heart. An oval, collagenous sheet, it bridges the gap between the arches of the aortic valve annulus which support the anterior and right posterior leaflets. Posteriorly it blends into the anterior surface of the right fibrous trigone.

Anteriorly, it is intermediate to the right and left ventricles and it forms the interventricular septum at this point. Posteriorly, it is intermediate to the right atrium and left ventricle. The posterior surface of the pars membranacea septi is the site at which the atrioventricular bundle of the conducting system courses from the right atrium to the ventricles.