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 fi ...
heart
The heart is a muscular Organ (biology), organ 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 ca ...
. 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 spe ...
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 th ...
. However, the sinus venosus persists in the adult. In the adult, it is incorporated into the wall of the right atrium 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 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 vena ...
; 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 uppe ...
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 vena ...
(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
In anatomy, the coronary sinus () is a collection of veins joined together t ...
of the left atrium, whereas the right part becomes incorporated into the right atrium 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.
See also
*
Atrial septal defect
Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this d ...
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 5% of atrial septal defects.Robbins and Cotran Pathologic Basis of Disease 8th Edition
They can occur near the supe ...