[1] During each cardiac cycle the interventricular septum contracts by shortening longitudinally and becoming thicker.

The interventricular septum is the stout wall separating the ventricles, the lower chambers of the heart, from one another.

The ventricular septum is directed obliquely backward to the right and curved with the convexity toward the right ventricle; its margins correspond with the anterior and posterior interventricular sulci.

[2] The muscular part of the interventricular septum derives from the bulboventricular flange which is developed due to differential growth of primitive ventricle and bulbous cordis.

Membranous part has a neural crest origin which connects the upper free margin of the bulboventricular flange and anterior and posterior endocardial cushions of atrio ventricular canal.