Sinus Venosus, Atria, IAS, Pulmonary Veins, Valves, Arches Flashcards
(39 cards)
The sinus venosus receives 3 pairs of veins. The are____, ____, and _____.
The vitelline veins, the umbilical veins, and the cardinal veins.
What happens to the left sinus horn and the transverse portion of the sinus venosus?
They become more separated from the left side of the atrium by a deep fold.
As the heart grows, what happens to the right sinus horn?
It becomes more vertical and incorporated into the floor of the RA.
How are folds produced within the atrial cardiac wall?
By the incorporation of the sinus venosus and the right and left sinus horns.
What arises at the sinoatrial junction?
A right sinus (venous) valve forms on the right, and a left sinus (venous) valve forms on the left.
Superiorly, what do the R/L sinus (venous) valves join to form?
The septum spurium
What does the left sinus (venous) valve fuse with?
The atrial septum
What does the inferior portion of the right sinus (venous) valve form?
The valve of Eustachii, the Ostia of the coronary sinus, and the valve of Thebesii.
What produces a depression on the roof of the common atria?
The truncus arteriosus
How is the septum primum formed?
It is formed passively by the deepening of the depression created by the truncus arteriosis on the roof of the common atria.
What is the ostium primum?
It is the foramen between the right and left primitive atria.
As a result of the tissue of the septum primum growing and fusing with the endocardial cushions, the _______.
Ostium primum becomes smaller, and finally closes.
Before the ostium primum closes, what appears?
Perforations appear in the septum primum, posterosuperiorly.
What do the tiny perforations in the septum primum form?
They coalesce to form the ostium secundum to keep communication between the RA and LA.
What is the name of the second tissue layer which grows between the atria?
Septum secundum
How is the septum secundum formed?
It is formed by the continuous folding of the interseptovalvular space and it is thicker and more muscular than the septum primum.
At this point there are 2 septums. What are they? And how are they growing?
The septum primum is growing towards the endocardial cushions.
The septum secundum is growing inferiorly and posteriorly.
What is the foramen ovale?
It is an opening in the interatrial septum allowing communication between the RA and LA.
What vessel arises from the wall of the LA, and what does it connect with?
A single pulmonary vein that connects to the splanchic plexus of vasculature behind the LA at the level of the lung buds.
How are the remaining 3 pulmonary veins formed?
By magic!
What lines the AV canal and the R/L atrioventricular orifices?
Mesenchymal tissue
Each AV orifice contains small ________.
Protuberances from the lateral endocardial cushions.
What valves do these endocardial cushions give rise to?
The ALMV and the major portion of the ALTV only.
Where does the major component of leaflet formation come from?
The ventricular wall
