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External Ear

(consists of)

- the Auricle
-external auditory canal (meatus)

(is made of?)


-made of flexible cartilage

external auditory canal


What does the external auditory canal do?

transmits sound

Middle Ear

(consists of)

-Tympanic membrane
-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?


order of the 3 bones in the ear?

1) malus
2) incus
3) stapes

Malus =


Incus =


Stapes =


The malus, incus, and stirrup are what?

synovial joints

synovial joints =

fluid in between bones = movement

Which cranial nerve is the auditory one?


cranial nerve 8 =

-acoustic nerve

main purpose of cranial nerve ____?

hearing and balance

Eustation tube =



Inner ear

(consists of)

-oval window
-semi-circular canals (7 parts) lateral, posterior, superior

External auditory canal
(what shape is it?)

it is "S" shaped

The external auditory canal opens through what?

it opens through the temporal bone

of the external auditory canal?

to transmit sound, collects sound

of the external auditory canal

ceruminous glands

Ceruminous glands secrete what?


cerumen =

ear wax

purpose of cerumen?

traps bacteria and debris

of the external auditory canal

covered/lined with
-ciliated epithelium

(Middle ear)
Purpose of the tympanic membrane?

turns sound waves into vibrations

(Middle ear)
Auditory ossicles (x3)


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


(Inner ear)
Membranous labyrinth


(Inner ear)
Semicircular canals

maintain equilibrium (balance)
-lateral, superior, posterior

(Inner ear)

-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


4) Electrochemical

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

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