Hearing and EquilibriumHearing and Equilibrium

Outer EarOuter Ear Auricle– “ear” shell-Auricle– “ear” shell-

shaped, surrounds shaped, surrounds external opening to external opening to auditory canalauditory canal

Auditory canal – Auditory canal – channel through channel through temporal bonetemporal bone

Tympanic Tympanic membrane-membrane-eardrum; vibrates eardrum; vibrates when stimulated by when stimulated by sound waves.sound waves.

Middle EarMiddle Ear

Air filled cavity called Air filled cavity called tympanic cavity tympanic cavity (middle ear cavity)(middle ear cavity)

From eardrum to From eardrum to bony wall with oval bony wall with oval and round windowand round window

Auditory tube runs Auditory tube runs down connecting ear down connecting ear to throatto throat

Functional parts of middle Functional parts of middle earear Ossicles- 3 small bonesOssicles- 3 small bones

Hammer (malleus), Anvil Hammer (malleus), Anvil (incus), and Stirrup (incus), and Stirrup (stapes)(stapes)

Eardrum vibrates hammer, Eardrum vibrates hammer, which moves anvil, which which moves anvil, which then moves stirrup, then moves stirrup, opening oval window.opening oval window.

Oval window moves fluids Oval window moves fluids inside inner earinside inner ear

Inner EarInner Ear

Located deep Located deep inside temporal inside temporal bone (behind eye bone (behind eye socket)socket)

Contains 3 major Contains 3 major divisionsdivisions

Anatomy of Inner earAnatomy of Inner ear Cochlea- contains Cochlea- contains

auditory (cochlear) auditory (cochlear) nerve, which nerve, which transmits sound transmits sound impulses; hair cells impulses; hair cells receive vibrations receive vibrations from oval window, from oval window, indicating soundindicating sound

Different pitches Different pitches affect different areas affect different areas of cochleaof cochlea

Semicircular canalSemicircular canal

Located in inner earLocated in inner ear Responsible for Responsible for

maintaining maintaining balance/equilibriumbalance/equilibrium

Otoliths float inside Otoliths float inside canalcanal

Hair cells recognize Hair cells recognize when the otolith when the otolith moves, alerting the moves, alerting the body of its positioning body of its positioning when staticwhen static

Dynamic equilibriumDynamic equilibrium

Position while Position while moving is moving is determined in determined in semicircular canalsemicircular canal

Triggered when Triggered when spinning, moving spinning, moving on a boat, etc.on a boat, etc.

Causes dizziness Causes dizziness and motion sicknessand motion sickness

Types of DeafnessTypes of Deafness

Conduction – Conduction – problem in problem in conduction of sound conduction of sound vibrations; hearing vibrations; hearing aids can help by aids can help by transmitting sound transmitting sound to/through boneto/through bone

Sensorineural – Sensorineural – degeneration or degeneration or damage to nerves damage to nerves which carry which carry impulse.impulse.