Download Ear and hearing notes

Hearing and Equilibrium
Outer Ear
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Auricle– “ear” shellshaped, surrounds
external opening to
auditory canal
Auditory canal –
channel through
temporal bone
Tympanic membraneeardrum; vibrates
when stimulated by
sound waves.
Middle Ear
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Air filled cavity called
tympanic cavity
(middle ear cavity)
From eardrum to
bony wall with oval
and round window
Auditory tube runs
down connecting ear
to throat
Functional parts of middle ear
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Ossicles- 3 small bones
Hammer (malleus), Anvil
(incus), and Stirrup (stapes)
Eardrum vibrates hammer,
which moves anvil, which
then moves stirrup, opening
oval window.
Oval window moves fluids
inside inner ear
Inner Ear
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Located deep inside
temporal bone
(behind eye socket)
Contains 3 major
divisions
Anatomy of Inner ear
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Cochlea- contains
auditory (cochlear)
nerve, which transmits
sound impulses; hair
cells receive vibrations
from oval window,
indicating sound
Different pitches affect
different areas of
cochlea
Semicircular canal
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Located in inner ear
Responsible for
maintaining
balance/equilibrium
Otoliths float inside canal
Hair cells recognize
when the otolith moves,
alerting the body of its
positioning when static
Dynamic equilibrium
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Position while moving
is determined in
semicircular canal
Triggered when
spinning, moving on a
boat, etc.
Causes dizziness and
motion sickness
Types of Deafness
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Conduction – problem
in conduction of
sound vibrations;
hearing aids can help
by transmitting sound
to/through bone
Sensorineural –
degeneration or
damage to nerves
which carry impulse.