Cardiac septa

The heart contains two main septa four main cardiac septa: the interatrial septum, the interventricular septum but two other septa may be described: the atrioventricular septum, and the conal (infundibular) septum.

• The interatrial septum separates the right and left atria and consists of two main components: the septum primum and septum secundum.

• The interventricular septum separates the right and left ventricles and has both muscular and membranous components. The muscular portion comprises the majority of the septum and develops concomitant with ventricular chamber formation. It can be subdivided into inlet, trabecular, and outlet portions based on anatomic landmarks. The membranous septum is a smaller fibrous component derived from the rightward margins of the atrioventricular cushions. The interventricular septum accommodates the ventricular portion of the conduction system and contributes to the mechanical function of both ventricles.

• The atrioventricular septum is located at the junction where the atrial and ventricular septa meet the cardiac valves. This region includes the membranous septum, central fibrous body, and the base of the interventricular septum.

• The conal (infundibular) septum separates the aortic and pulmonary outflow tracts. This structure is not officialy listed in the veterinary and human official anatomic nomenclatures.