Collects sound waves and
channel them down the
auditory channel
Vibration of the
tympanic membrane
Middle ear
Auditory ossicles
Malleus
Sound waves
traveling through
air must be
converted into
pressure waves
in fluid.
When the sound waves move the tympanic membrane, the chain
of ossicles also moves, pushing the footplate of the stapes into
the oval window and displaces the fluid in the cochlea
Incus
Stapes
Inner ear
Sensory
organ
Cochlea
3 coiled tubes
Scala vestibuli
Contains
perilymph
Scala media
Contains
endolymph
Scala tympani
Contains perilymph
Reissner's membrane
Basilar
membrane
Organ of Corti
lies on it
Inner hair
cells
Outer hair
cells
Helicotrema
Point of
communication
between the
scala vestibuli
and scala
tympani. Scala
media does
not
communicate
with these
two scala.
Tympanic
membrane
Separates
external ear
from internal
ear
Pearly gray and
translucent, with a
sharp light reflex
and bony landmarks
Hearing loss
Conductive
hearing loss
sound waves are not
adequately conducted through
the external or middle ear
Cause: Damage to cochlea, CN VIII
or central auditory connections.
Air conduction> bone conduction
Sensorineural hearing loss
Sound waves are not translated into
nerve signals and not recognized as sound
sensations by the brain.
Etiology: physical blockade
of the ear canal
Bone conduction> air
conduction
Presbycusis
partial loss of hearing as a
result of loss of hair cells