Muscular part of interventricular septum

The muscular part of the interventricular septum forms the majority of the interventricular septum separating the right and left ventricles (the upper and posterior part is thin and called the membranous part of interventricular septum) .

The muscular part of the interventricular septum is a thick, muscular structure that extends from the cardiac apex upward toward the base, and is anatomically divided into three main regions: the inlet, trabecular (or central), and outlet (or infundibular) portions:

• Inlet septum, located near the atrioventricular valves, that extends posteriorly to the cardiac crux, separating the atrioventricular valves

• Trabecular (or central) septum, the largest part, divides the anatomic bodies of the left and right ventricles

• Infundibular septum that is located near the ventricular outflow tract, directly inferior to the junction between the commissure between the right and left coronary cusps of the aortic valve and the pulmonic commissure and distinct from the rest of the septum both in orientation and perfusion

The muscular septum is continuous with the free wall of the left ventricle and is perfused by septal branches of the left anterior descending and posterior descending coronary arteries.

An abnormal communication may exist between the ventricles at this part owing to defective development of the membranous septum.