Organ
Interatrial septum
True partition and folds between the atrial chambers
High-yield
Distinguish a true septal defect from a patent foramen ovale. The former lacks tissue, whereas the latter retains a potentially separable fetal flap.
Overview
The apparent wall between the atria is larger than the tissue that directly separates their cavities. The fossa-ovalis floor and its immediate margins form the true septal area; other parts of the apparent boundary include folds of atrial wall.
Reference facts
- Location
- Oblique boundary between the right and left atria
- Parts
- Fossa ovalis and immediate septal margins, bordered by thicker folded atrial wall
- Blood supply
- Anastomosing atrial branches of the right and left coronary arteries
- Innervation
- Cardiac neural networks supply atrial tissue; the atrioventricular node is near the inferior septal region
- Relations
- Aortic root anteriorly; inferior caval and coronary sinus regions on the lower right atrial side
- Function
- Separates atrial blood streams after closure of the fetal interatrial communication
Clinical correlation
A secundum atrial septal defect lies in the fossa-ovalis region and commonly allows left-to-right flow after birth. The amount and direction of shunting depend on pressures, ventricular filling properties and defect size.
Frequently asked questions
Where is the interatrial septum located?
The interatrial septum lies oblique boundary between the right and left atria.
What does the interatrial septum do?
Separates atrial blood streams after closure of the fetal interatrial communication.
What are the parts of the interatrial septum?
The parts of the interatrial septum are the fossa ovalis and immediate septal margins, bordered by thicker folded atrial wall.
What is the blood supply of the interatrial septum?
The interatrial septum is supplied by the anastomosing atrial branches of the right and left coronary arteries.