Septum secundum arises from:
Septum secundum Grows down from theroof of the common atrium(primitive atrium)toward the atrioventricular endocardial cushions. Present on the right side of the septum primum. Contains foramen ovale for the pasage of blood from RA to LA. Note =Order of hea tube on day 21 from caudal to cranial Sinus venosus Atrium Ventricle Bulbus cordis Truncus aeriosus
Bulbus cordis
Primitive ventricle
Primitive atrium
Sinus venosus
CVS Embryology