What is the full form of Av foramen and it's function in heart?

Dear Student, 
Av (atrial ventriular in embryo) foramen is basically known as foramen ovale. It is present in the new born baby(fused),  present in the interatrial septum. It is basically functional in embryo stage but by the time of birth it fuses. In embryo it allows flow of blood from right atrium to left atrium.
Regards.