Atrioventricular orifice [right and left]

The right and left atrioventricular orifices are the openings in the heart through which blood flows from the atria into the ventricles, specifically from the right atrium to the right ventricle and from the left atrium to the left ventricle, respectively. Each orifice is guarded by an atrioventricular valve: the tricuspid valve on the right and the mitral valve on the left, which regulate unidirectional blood flow and prevent backflow during ventricular contraction.