Which structures of the middle ear are involved in movement of the ossicles?
a. vestibule and stapedius c. stapedius and eustachian tube
b. tensor tympani and stapedius d. eustachian tube and tensor tympani
B
The tensor tympani and the stapedius are two tiny muscles involved in movement of the ossicles. The tensor tympani maintains the tension of the tympanic membrane and pulls the malleus inward when it contracts. The stapedius works in opposition by pulling the stapes outward. This coordinated movement is an important mechanism in reducing the intensity of loud sounds that might otherwise result in serious damage to hearing receptors in the inner ear. The eustachian tube serves as a channel through which air pressure within the cavity can be equalized with air pressure outside to maintain normal hearing. The vestibule is located between the cochlea and the semicircular canals and is important in both hearing and balance.
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