The
sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the
chordateChordates are animals which are either vertebrates or one of several closely related invertebrates. They are united by having, for at least some period of their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail...
heartThe heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. In humans, it exists distinctly only in the
embryoAn embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
nic heart, where it is found between the two
venae cavaeThe superior and inferior vena cava are collectively called the venae cavae. They are the veins that return deoxygenated blood from the body into the heart. They both empty into the right atrium....
. In the adult, it is incorporated into the wall of the
right atriumThe right atrium is one of four chambers in the hearts of mammals and archosaurs...
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 terminalisThe Crista Terminalis represents the junction between the sinus venosus and the heart in the developing embryo. In the development of the human heart, the right horn and transverse portion of the sinus venosus ultimately become incorporated with and form a part of the adult right atrium...
. The sinus venosus also forms the SA node and the
coronary sinusThe coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart. It is present in all mammals, including humans...
.
In the embryo, the thin walls of the sinus venosus are connected below with the
right ventricleThe right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
, and medially with the
left atriumThe left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
, but are free in the rest of their extent. It receives blood from the vitelline vein,
umbilical veinThe umbilical vein is a vein present during fetal development that carries oxygenated blood from the placenta to the growing fetus.The blood pressure inside the umbilical vein is approximately 20 mmHg.-Development:...
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 sinusThe coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart. It is present in all mammals, including humans...
and oblique vein of the
left atriumThe left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
, whereas the right part becomes incorporated into the
right atriumThe right atrium is one of four chambers in the hearts of mammals and archosaurs...
to form the sinus venarum.
See also
- Atrial septal defect
- Bulbus cordis
The bulbus cordis lies ventral to the primitive ventricle after the developing heart assumes its S-shaped form...
- Ducts of Cuvier
During development of the veins, the first indication of a parietal system consists in the appearance of two short transverse veins, the ducts of Cuvier , which open, one on either side, into the sinus venosus. Each of these ducts receives an ascending and descending vein...
- Primitive ventricle
The embryonic ventricle or primitive ventricle of the developing heart gives rise to the trabeculated parts of the left and right ventricles...
- Primitive atrium
The primitive atrium is a term used to describe a stage in the embryonic development of the human heart. It grows rapidly and partially encircles the bulbus cordis; the groove against which the bulbus cordis lies is the first indication of a division into right and left atria.The cavity of the...
- Ductus venosus
In the fetus, the ductus venosus shunts approximately half of the blood flow of the umbilical vein directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus, it...
- Truncus Arteriosus
The truncus arteriosus and bulbus cordis are divided by the aorticopulmonary septum. The truncus arteriosus gives rise to the ascending aorta and the pulmonary trunk. The caudal end of the bulbus cordis gives rise to the smooth parts of the left and right ventricles...
- Sinus venosus atrial septal defect
A Sinus venosus atrial septal defect is a type of atrial septal defect primarily associated with the sinus venosus.They represent 10% of atrial septal defects.They can occur near the superior vena cava or inferior vena cava, but the former are more common....
External links
- Gross anatomy of the adult heart - "Right atrium, internal structure, anterior view"