The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the

chordate A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five ...

heart The heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon diox ...

. In mammals, it exists distinctly only in the

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

nic heart, where it is found between the two

venae cavae In anatomy, the venae cavae (; singular: vena cava ; ) are two large veins (great vessels) that return deoxygenated blood from the body into the heart. In humans they are the superior vena cava and the inferior vena cava, and both empty into the ...

. However, the sinus venosus persists in the adult. In the adult, it is incorporated into the wall of the

right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two a ...

to form a smooth part called the sinus venarum, which is separated from the rest of the atrium by a ridge of fibres called the crista terminalis. The sinus venosus also forms the

sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approxi ...

and the

coronary sinus In anatomy, the coronary sinus () is a collection of veins joined together to form a large vessel that collects blood from the heart muscle ( myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior ven ...

; in (most) mammals only. In the embryo, the thin walls of the sinus venosus are connected below with the

right ventricle A ventricle is one of two large chambers toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in the upper ...

, and medially with the

left atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two ...

, but are free in the rest of their extent. It receives blood from the vitelline vein, umbilical vein and

common cardinal vein The common cardinal veins, also known as the ducts of Cuvier,coronary sinus In anatomy, the coronary sinus () is a collection of veins joined together to form a large vessel that collects blood from the heart muscle ( myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior ven ...

(right atrium) and

oblique vein The oblique vein of the left atrium (oblique vein of Marshall) is a small vessel which descends obliquely on the back of the left atrium and ends in the coronary sinus near its left extremity; it is continuous above with the ligament of the left ve ...

of the

, whereas the right part becomes incorporated into the

to form the sinus venarum.

Additional images

File:Gray461.png, Diagram to illustrate the simple tubular condition of the heart. File:Gray462.png, Heart of human embryo of about fourteen days. File:Gray477.svg, Scheme of arrangement of parietal veins.

References

External links

* - Gross anatomy of the adult heart * - "Right atrium, internal structure, anterior view" {{Authority control Embryology of cardiovascular system de:Sinus venosus zh:静脉窦

Additional images

See also

References

External links