The size of the Fenestra vestibule on an average is
3.50 mm long and 2.50 mm wide
3.25 mm long and 1.75 mm wide
3.75 mm long and 1.50 mm wide
4.00 mm long and 2.00 mm wide
The size of the Fenestra vestibule on an average is 3.25 mm long and 1.75 mm wide. Ref- Dhingra ENT Textbook 6th edition.
Ear