fossa ovalis of heart


fossa ovalis of heart

An oval depression in the septal wall of the right atrium; it has a raised rim along its top and front edges. In the embryo, the floor of the fossa ovalis is a flap valve (the primary atrial septum or septum primum) that lets blood flow from the right atrium to the left atrium, bypassing the lungs. If the flap valve fails to seal after birth, the heart can have an atrial septal defect. See also: fossa