Organ
Fossa ovalis
Thin atrial depression left by a fetal passage
High-yield
The floor comes mainly from septum primum. Much of the surrounding rim reflects folded atrial wall; failure of flap fusion can leave a patent foramen ovale rather than a hole of missing septal tissue.
Overview
Seen from the right atrium, the fossa ovalis is a shallow depression with a raised rim. Its thin floor is the former flap of the fetal foramen ovale, which allowed blood to pass from right atrium to left before birth.
Reference facts
- Location
- Septal aspect of the right atrium, above the inferior caval region
- Parts
- Thin flap-derived floor and surrounding muscular limbus
- Blood supply
- Small atrial arterial branches; the thin central region is relatively sparsely vascularized
- Innervation
- Autonomic and sensory fibers serving the surrounding atrial tissues
- Relations
- Aortic root lies anterosuperiorly; inferior caval and coronary sinus openings are nearby inferiorly
- Function
- Marks the normally closed fetal interatrial passage
Clinical correlation
Most patent foramina ovalia cause no symptoms. If right-to-left flow occurs, a venous embolus can sometimes cross into systemic circulation; this possibility does not make every PFO a cause of stroke.
Frequently asked questions
Where is the fossa ovalis located?
The fossa ovalis lies septal aspect of the right atrium, above the inferior caval region.
What does the fossa ovalis do?
Marks the normally closed fetal interatrial passage.
What are the parts of the fossa ovalis?
The parts of the fossa ovalis are the thin flap-derived floor and surrounding muscular limbus.
What is the blood supply of the fossa ovalis?
Small atrial arterial branches; the thin central region is relatively sparsely vascularized.