Tags: Anatomical Structure, Embryology.
This article is on an embryological structure. For the heart defect of the same name please see atrial septal defect.The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In mammals it exists distinctly only in the embryonic heart (where it is found between the two venae cavae); in nonmammalian chordates however the sinus venosus persists in the adult.
