Prior to the entry of blood into right atrium, the received blood by major veins in frog is poured into

Prior to the entry of blood into right atrium, the received blood by major veins in frog is poured into sinus venosus. Sinus venous is a triangular chamber found on the dorsal side of heart. It receives two precaval veins and one postcaval vein and opens into right atrium of heart.