The middle ear
The middle ear refers to the hollowed air-filled bony space (tympanic cavity) in the temporal bone of the skull behind the eardrum. It is just separated from the outer ear by the ear drum. There are three tiny bones called ossicles in the tympanic cavity that vibrates when exposed to sound waves, namely:
and Malleus
and Incus
and Stapes – the smallest bone in the human body
These bones form a chain around the middle ear and extend to the oval window of the inner ear and their main function is to amplify sound.
The middle ear connects to the back of the throat and nose through the Eustachian tube. The Eustachian tube is the auditory openings that we open when we yawn or swallow.
Function of middle ear ossicles
The most basic function of the ear is hearing.
How does it work?
The first step is when the pinna collects external sounds that enter through the meatus or ear canal as sound waves. The ear drum begins to vibrate as these sound waves strikes. These vibrations pass through to the three ossicles of the middle ear (malleus, incus and stapes) where they are amplified. As the transmission proceeds, the vibrations first hit the malleus, then the malleus pushes the incus , and the incus hits the stapes.
The vibrations are finally interpreted as sound in the brain after being transmitted and transformed into nerve signals by the cochlea (snail shaped component of the inner ear). This is due to the connectivity of the oval window of the inner ear to the edge of the stapes. When the stapes vibrates, they always transmit the sound vibrations to the inner ear.
(Courtesy-3D CT images-volume rendered- by Vergin G.S. and Dr Asha FRCR ,Travancore scans)
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