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Flashcards in Middle Ear Deck (19)
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0
Q

What is the TM?

A

A dividing wall
Not a part of outer or middle ear.. Technically both
One boundary of middle ear
Cone shaped - concave

1
Q

TM held in place by..

A

Fibers and cartilage

2
Q

Main portion of middle ear..

A

Between TM and promontory

3
Q

Middle ear cavity

A

2cc’s volume
Contains smaller upper cavity - epitympanic recess
Connected to nasopharynx by Eustachian tube
Three bones: malleus, incus, stapes

4
Q

3 layers of TM

A

Outer - same skin as bony portion of canal
Middle - (most imp) contains radial and circular fibres
Inner - lined w mucous membrane

5
Q

Pars flacida

A

Sparse area near the top of TM

Lots of lesions can happen there

6
Q

Umbo

A

Region of max concavity of TM

7
Q

Malleus

A

Bone that connects to the TM
Most lateral of the three ossicles
This is what pulls back the eardrum
Forms the cone of light (if drum not healthy, won’t have this)
Head connects to incus and extends into epitympanic recess

8
Q

Incus

A

Middle ossicle

Connects to malleus and stapes

9
Q

Stapes

A

Connects to incus

Footplate connects to oval window

10
Q

Muscles of the middle ear

A

Tensor tympani

Stapedius

11
Q

Sound travels thru ME in 3 ways

A
  1. bone conduction
  2. air in middle ear cavity
  3. ossicular chain - most effective - vibrates oval window
12
Q

Inner ear filled with…

A

Fluid

13
Q

Impedance mismatch

A

Sound moves from air to fluid going from outer to middle ear, so we need a lot more pressure to move the sound effectively

  • it’s hard to move anything in a substance thicker than air
14
Q

2 ways our MEs compensate for the impedance mismatch

A
  1. Area differential (impedance matching)

2. lever action

15
Q

Air pressure in ME

A

Must be the same as atmosphere
Failure to regulate this -> chronic ear disease
Eustachian tube allows us to equalize the pressure

16
Q

Stapedius

A

tenses the membrane of the oval window

reduces sounds

17
Q

Tensor Tympani

A

Resonds reflexivel bilaterally

Doesn’t have much effect on sound

18
Q

ME transduces ______ to _______

A

Acoustic energy to mechanical energy