The External and Middle Ear Flashcards Preview

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Flashcards in The External and Middle Ear Deck (15)
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1
Q

what is the function of the external ear

A

collect soundwaves and funnels them into the external acoustic meatus

2
Q

what nerves supply the external ear

A

CN VII(facial nerve), CN V3(auriculotemporal), C2,3(via lesser occipital nerve and greater auricular nerve)

3
Q

what is the external ear called

A

the Pinna or Auricle

4
Q

what is the main function of the middle ear and tympanic cavity

A

to conduct soundwaves in air, by bone conduction mechanism of hearing, towards fluid filled cavities of inner ear

5
Q

what are the auditory ossicles lateral to medial, and therefore from largest to smallest

A

Malleus(hammer), Incus(anvil) and Stapes(stirrup)

found in middle ear, in tympanic cavity

6
Q

where do the tensor tympani muscle and stapedius muscle run from

A

tensor tympani muscle = cartilaginous portion of eustachian tube to handle of malleus
stapedius muscle = from pyramidal eminence to neck of stapes

7
Q

what is the role of the tensor tympani muscle in the middle ear

A

dampens sound by reducing vibration of tympanic membrane

8
Q

what is the role of the stapedius muscle in the middle ear

A

dampens sound by reducing vibrations of stapes on oval window

9
Q

what are tensor tympani and stapedius muscle innervated by

A

tensor tympani = CN V3

stapedius = CN VII

10
Q

what is the typical middle ear pressure, and how is this pressure achieved

A

typically equal to atmospheric air pressure

palate muscles open the eustachian tube to equalise pressure

11
Q

what happens to the tympanic membrane when the tympanic cavity air pressure is greater or lower than atmospheric air pressure

A
greater = tympanic membrane is pushed out
lower = tympanic membrane is pushed in
12
Q

what results from inequality between tympanic and atmospheric air pressures

A

reduced vibration of ossicles and possibly barotrauma

13
Q

describe where the eustachian(auditory) tube runs

A

runs from the anterior wall of the middle ear cavity to the nasopharynx
(therefore some inflammation from middle ear can spread to pharynx)

14
Q

what is responsible for general sensory innervation of the middle ear

A

CN IX, via tympanic plexus

15
Q

in the tympanic cavity what is the role of the oval and round windows

A

oval window = received footplate of the stapes

round window = dissipates the forces/vibrations from the cochlea