Välikorvat

Välikorvat, known scientifically as the middle ear, is the air-filled cavity within the temporal bone of the skull that transmits sound from the outer ear to the inner ear. It is separated from the external auditory canal by the tympanic membrane, or eardrum, and from the inner ear by the oval window and the round window. The primary function of the middle ear is to efficiently transfer airborne sound vibrations into fluidborne vibrations that can be processed by the cochlea.

Within the tympanic cavity, a chain of three small bones, collectively called the ossicles, plays a crucial role in this transmission. These ossicles are the malleus (hammer), incus (anvil), and stapes (stirrup). The malleus is attached to the tympanic membrane and vibrates with it. These vibrations are then passed to the incus, and subsequently to the stapes. The footplate of the stapes fits into the oval window, transferring the mechanical energy to the fluid-filled cochlea of the inner ear. The ossicles also act as a lever system, amplifying the force of the vibrations and helping to overcome the impedance mismatch between air and the fluid of the inner ear.

The middle ear is connected to the nasopharynx by the Eustachian tube, also known as the auditory tube. This tube serves to equalize the air pressure on both sides of the tympanic membrane, which is essential for optimal hearing and preventing damage to the eardrum. If the pressure difference becomes too great, it can affect the mobility of the tympanic membrane and ossicles, leading to temporary hearing loss. The middle ear is lined with mucous membrane and is generally considered sterile, although infections of the upper respiratory tract can sometimes spread to the middle ear, causing otitis media.