EAREAR

Outer EarOuter Ear

FunctionPinnaExternal auditory meatus (canal)

– Ceruminous glands

Tympanic membrane– Eardrum

Middle EarMiddle Ear

Auditory = Eustachian tubeOssicles

– Malleus– Incus– Stapes

Oval windowRound window

Inner EarInner Ear

Osseous labyrinth filled with perilymphMembranous labyrinth filled with

endolymph

Inner EarInner Ear

Vestibule– Utricle– Saccule

Inner EarInner Ear

Semicircular canals– Semicircular ducts

Inner EarInner Ear

CochleaVestibular MembraneBasilar membraneCochlear duct (endolymph)

Inner Ear - CochleaInner Ear - Cochlea

Scala tympaniScala vestibuliSpiral Organ = Organ of Corti

– Receptors for hearing are hair cells on the basilar membrane in the Spiral Organ

HearingHearing

Sound transmission– Tympanic Reflex

High frequency at base of cochleaLow frequency at apex of cochlea

HearingHearing

Auditory pathway

HearingHearing

Pitch determination (20-20,000 cps)

HearingHearing

Loudness 1-120 db

HearingHearing

Localization of soundTime reaching ear and loudness for both

ears

EquilibriumEquilibrium

Utricle and SacculeMacula = receptorOtolithLinear AccelerationLinear DecelerationHead Position

EquilibriumEquilibrium

Semicircular ducts with ampulla- widened part

Crista – hair cellsCupula = endolymphRotational accelerationRotational decelerationVestibular nystagmus

EquilibriumEquilibrium

Dynamic whole body equilibrium