ABSTRACT
This valve is designed so that blood returning from the rest of the body will supply both atria. The necessity for this valve has to do with the flow of blood. In the adult, blood returns to the left atrium from the lungs. However, because of the underdeveloped nature of the lungs during prenatal existence, the lungs supply essentially no blood to the left atrium. Instead, blood is supplied to the left atrium from the right atrium via the foramen ovale. This provides the left atrium with a load to pump, which is necessary for its proper development.
