The Endocardial Cushions are primarily involved in the formation of which cardiac structures?

The endocardial cushions play a crucial role in the development of the atrioventricular valves, which include the mitral valve on the left side of the heart and the tricuspid valve on the right side. During embryonic development, the endocardial cushions are structures that form in the heart's atrioventricular canal and contribute to the septation of the heart, particularly in the division of the atria and ventricles. As development progresses, these cushions undergo a process of proliferation and transformation to form the leaflets of the atrioventricular valves. This ensures that blood flows properly from the atria to the ventricles and prevents backflow during ventricular contraction.

In contrast, the semilunar valves, coronary arteries, and epicardial layers have different developmental origins and processes. The semilunar valves arise from different embryonic structures, while the coronary arteries develop from the epicardium. The epicardial layers themselves do not form from endocardial cushions, as they are part of the outer layer of the heart. Thus, the association of the endocardial cushions with the formation of the atrioventricular valves is critical in understanding normal cardiac function and anatomy.