Round window
Fenestra cochleae
Sensory (eye & ear)OrgansHeadLeft and right
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- What it is
- The fenestra cochleae: a round opening at the base of the scala tympani, closed by a thin, flexible secondary tympanic membrane, lying below and behind the oval window in a small niche.
- Function
- Bulges outward when the stapes pushes in, letting the incompressible inner-ear fluid move so the basilar membrane can vibrate.
- Size
- About 2 mm in diameter; membrane about 70 micrometres thick.
- Clinical note
- A route for delivering drugs to the inner ear and the usual entry point for cochlear-implant electrodes.