This article is on an embryological structure. For the heart defect of the same name, please see atrial septal defect.

Sinus venosus
Interior of dorsal half of heart from a human embryo of about thirty days, frontal view. (Opening of sinus venosus labeled at center top.)
Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries. (Sinus venosus labeled at center left.)
Gray's	subject #138 528
Carnegie stage	9

The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In humans, it exists distinctly only in the embryonic heart, where it is found between the two venae cavae. In the adult, it is incorporated into the wall of the right atrium to form a smooth part called the sinus venarum, also known as the venarum sinus, which is separated from the rest of the atrium by a ridge of fibres called the crista terminalis. The sinus venosus also forms the SA node and the coronary sinus.

In the embryo, the thin walls of the sinus venosus are connected below with the right ventricle, and medially with the left atrium, but are free in the rest of their extent. It receives blood from the vitelline vein, umbilical vein and common cardinal vein.

It originally starts as a paired structure but shifts towards associating only with the right atrium as the embryonic heart develops. The left portion shrinks in size and eventually forms the coronary sinus and oblique vein of the left atrium, whereas the right part becomes incorporated into the right atrium to form the sinus venarum.

[edit] Additional images

Diagram to illustrate the simple tubular condition of the heart.

Heart of human embryo of about fourteen days.

Scheme of arrangement of parietal veins.

[edit] See also

• Atrial septal defect
• Bulbus cordis
• Ducts of Cuvier
• Primitive ventricle
• Primitive atrium
• Ductus venosus
• Truncus Arteriosus
• Sinus venosus atrial septal defect

[edit] External links

• 1483407420 at GPnotebook
• SUNY Labs 20:13-0102 - Gross anatomy of the adult heart
• Atlas of anatomy at UMich ht_rt_atrium - "Right atrium, internal structure, anterior view"
• sinus+venosus at eMedicine Dictionary

v • d • e Prenatal development/Mammalian development of circulatory system (GA 5) Vascular Blood island Development of arteries Dorsal aorta · Aortic arches Development of veins Cardinal veins · Ducts of Cuvier Fetal circulation umbilical cord: Umbilical vein → Ductus venosus → Inferior vena cava → Heart → Pulmonary artery → Ductus arteriosus → Umbilical artery yolk sac: Vitelline veins · Vitelline arteries Heart development Primitive heart tube Truncus arteriosus · Bulbus cordis · Primitive ventricle · Primitive atrium · Sinus venosus Septa/ostia Endocardial cushions/Septum intermedium · Ostium primum · Septum primum (Ostium secundum) · Septum secundum (Foramen ovale) · Aorticopulmonary septum Other Atrial canal heart navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc