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Ear Anatomy / Physiology

STUDY
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External Ear

(consists of)
- the Auricle
-lobe
-trygus
-external auditory canal (meatus)
Auricle
(AKA...)
(is made of?)
Pinna

-made of flexible cartilage
external auditory canal
(aka)
meatus
What does the external auditory canal do?
transmits sound
Middle Ear

(consists of)
-Tympanic membrane
-malus
-incus
-stirrup
-VIII (8) cranial nerve
-eustation tube
Tympanic membrane =
ear drum
What does the tympanic membrane do?
picks up sound waves
3 smallest bones in body?
malus
incus
stirrup
order of the 3 bones in the ear?
1) malus
2) incus
3) stapes
Malus =
hammer
Incus =
Anvil
Stapes =
Stirrup
The malus, incus, and stirrup are what?
synovial joints
synovial joints =
fluid in between bones = movement
Which cranial nerve is the auditory one?
VIII
(8)
cranial nerve 8 =
auditory
-vestibulocochlear
or
-acoustic nerve
main purpose of cranial nerve ____?
hearing and balance
Eustation tube =
(phyingotympanic)????

- PRESSURE
Inner ear

(consists of)
-oval window
-cochlea
-semi-circular canals (7 parts) lateral, posterior, superior
-vestibule
External auditory canal
(what shape is it?)
it is "S" shaped
The external auditory canal opens through what?
it opens through the temporal bone
Purpose
of the external auditory canal?
to transmit sound, collects sound
Glands
of the external auditory canal
ceruminous glands
Ceruminous glands secrete what?
cerumen
cerumen =
ear wax
purpose of cerumen?
traps bacteria and debris
Tissue
of the external auditory canal
covered/lined with
-ciliated epithelium
(Middle ear)
Purpose of the tympanic membrane?
turns sound waves into vibrations
(mechanical)
(Middle ear)
Auditory ossicles (x3)
-malleus
-incus
-stapes
purpose of the auditory ossicles?
to send vibrations to the inner ear
-also, transmit and amplify sound
(Middle ear)
Eustation tube

(located and function?)
-located middle ear to nasopharynx
(behind nose)

-purpose = equalize air pressure
(Middle ear)
Tympanic antrum

(located and function)
-opens to middle ear to mastoid

=purpose = equalize air pressure
(Inner ear)
Oval window
fluid filled
-vestibule (opening)
(Inner ear)
Bony labyrinth
perilymph
(around)
(Inner ear)
Membranous labyrinth
endolymph
(inside)
(Inner ear)
Semicircular canals
maintain equilibrium (balance)
-lateral, superior, posterior
(Inner ear)
Cochlea
-hearing
-houses the organ of Corti (hair cells)
-changes fluid signal to electrochemical
Organ of corti =
hair cells
Physiology of Hearing (x4)
1) Sound waves
2) Mechanical
3) Fluid movement
4) Electrochemical
1) Sound waves
Pinna (aurical) -external auditory meatus
2) Mechanical
Tympanic membrane vibrates the mallus,
then the incus,
then the stapes
3) Fluid movement
Oval window - fluid flows through the conchea over the hair cells of the Organ of Corti

which.....
4) Electrochemical
...which stimulate nerves and signal passes along cranial nerve VIII (vestibulocochlear nerve)
to the temporal lobe of the brain.