interatrial foramen primum
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Related to interatrial foramen primum: interatrial septum, Ostium secundum, common atrium, Ostium primum of Born
in·ter·a·tri·al fo·ra·men pri·'mum
1. in the embryonic heart, the temporary opening between right and left atria situated between the lower margin of the septum primum and the atrioventricular canal cushions;
2. in an adult heart, the abnormal persistence of the so-named communication, which is normal in young embryos.