Fossa ovalis and musculi pectinate
Looking into the right atrium you see the fossa ovalis, a saucer shaped depression on the interatrial septum. What is it a remnant of? If there was a hole in its place, what effect would it have on blood circulation? The parallel muscular ridges seen on the flap resemble a comb and are hence called musculi pectinate. (Remains of the primitive right atrium.)
Dr. S. Chandra
Dr. S. Chandra, Faculty of Medicine, Memorial University of Newfoundland
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