H&N - Inner ear

mechanism of sound entering ear

caught by pinna

travels through external auditory meatus

hits tympanic membrane

tympanic membrane vibrates causing pressure and is transmitted through ossicles

travels to stapes

stapes vibrate against membrane of ovalwindow

transmission of sound to inner ear and then to vestibule

function of the middle ear

amplification of sound

how does the middle ear amplify sound

travels from air to fluid

what is the vestibule of the inner ear

-central egg shaped cavity which contains saccule and urticle

-senses equilibrium

-contain hair cells that are clustered in the macula (lie under a thin layer of crystals called otoliths)

what is the function of cochlea

hearing- responds to pressure

what is the 2 types of fluid found in the inner ear

perilymph

endolymph

structures of organ of corti

basilar membrane, hair cells, and tectorial membrane

- basilar membrane reacts to pressure

- shearing action

- endolymph changes

hearing mechanism in cochlea

footplate of stapes moves in and out of oval window creating wave in scala vestibuli adn scala tympani

causes movement of basilar membrane and movement of inner and outer hair cells in organ of corti

cilia deflected and ion channels open

depolarisation and impulse sent to CN VIII

inner hair cells activate afferent nerves and outer hair cells amplify response

describe tonotopic arrangement

for every frequency there is a specific place on the basilar membrane where the hair cells are maximally sensitive to that frequency