interventricular septum (anatomy)
The interventricular septum is the wall of the heart intermediate to the right and left ventricles. Its surface markings correspond to the anterior and posterior interventricular grooves. It runs obliquely to the left and slightly inferiorly from posterior to anterior. Due to this angulation, the right ventricle tends to lie anteriorly and the left ventricle posteriorly.
Throughout most of its surface area, the septum is as muscular as the left ventricle. It tends to bulge into the chamber of the right ventricle producing a concavity on the left ventricular side. Nearer to the aortic valve orifice beneath the margins of the right and posterior leaflets, the septum becomes thinner and more fibrous. This region is termed the pars membranacea septi, or the membranous part of the interventricular septum. It is oval in shape.
The muscular and membranous parts of the interventricular septum have different developmental origins. The membranous part of the septum is the most frequent site for ventricular septal defects which are usually congenital.
Last reviewed 01/2018