The average diameter of the oval window is 5 mm, which is enough for the passage of thrombotic clots – emboli that can close the cerebral arteries causing ischemic stroke.
On the first inspiration, the pressure of the right atrium decreases due to a drop in resistance in the small circle, and the primary septum is pressed against the second septum, closing the oval window.
The oval window is a short channel between the two chambers of the heart – the atria (average length 5), located exactly along the blood flow coming from the inferior vena cava.