Opening of cranial vena cava

The cranial vena cava opens into the right atrium with the opening of cranial vena cava.

The opening of the cranial vena cava is located on the craniodorsal wall of the right atrium. It enters the smooth-walled portion of the atrium known as the sinus venarum. The opening lies cranial to the opening of the caudal vena cava and dorsal to the right atrioventricular (tricuspid) orifice.

The opening of the cranial vena cava is wide and non-valved. Unlike the caudal vena cava, which has a rudimentary valve in some species (Eustachian valve), the cranial vena cava in the dog has no valve or consistent valvular fold at its atrial entrance. This allows unimpeded venous return from the head, neck, thoracic limbs, and cranial thoracic wall.