1.2-3 Middle Ear and Eustachian Tube Flashcards

1
Q

Which cranial nerve passes through the middle ear?

A

Cranial Nerve 7 Facial Nerve

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2
Q

What is the name of the entrance of the mastoid antrum (air cells)?

A

Aditus Antrum

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3
Q

State the 5 functional outline of the middle ear in sound conduction:

A

Vibration of tympanic membrane
Vibration of the bone chain
Amplification of sound by middle ear by 3 mechanism
Frequency responses of the middle ear
Feedback control

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4
Q

True or False: The vibration of eardrum and oval window is even.

A

FALSE: UNEVEN

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5
Q

True or False: Eardrum vibration is larger on its inferior part

A

TRUE

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6
Q

What is the total gain provided by the area function of impedance matching?

A

25 dB

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7
Q

What is the total gain provided by the Lever Function of impedance matching?

A

2.5 dB

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8
Q

What is the total gain provided by the buckling membrane are of impedance matching?

A

6 dB gain

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9
Q

What are the two muscles in the middle ear?

A

Stapedius Muscle and Tensor Tympani

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10
Q

The tensor tympani is attached to the ?

A

Manubrium

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11
Q

Which is largest the stapedius or the tensor tympani?

A

Tensor Tympani

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12
Q

In which direction does the tensor tympani pull the TM?

A

medially

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13
Q

In which direction does the stapedius muscle pull the TM
and stapes?

A

laterally

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14
Q

Where is the stapedius muscle attached to?

A

Attached to the head of stapes

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15
Q

The stapedius muscle is smaller or larger than the tensor tympani?

A

smaller

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16
Q

Stapedius muscles pull the head of the Stapes to rotate _________, and _________

A

Stapedius muscles pull the head of Stapes to rotate posteriorly, and laterally

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17
Q

What is the relationship between ME muscles and acoustic reflex? (2)

A

Contraction evoked by loud sound
Increases the stiffness of the ME bone chain

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18
Q

True or False: In humans, stapedius muscle play greater role in AR than tensor tympani m.

A

TRUE!

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19
Q

Describe the ME impedance test (4):

A

Is done in external ear canal
Non invasive
Best way to measure AR in clinics
But can’t tell the source of AR (Stapedius vs. TT)`

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20
Q

What are the 3 possible role of the eustachian tube?

A

1) Balancing air pressure
2) Pathway for cleaning debris through mucociliary transportation
3) Protection against infection from nasal cavity and from loud sound of own voice

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21
Q

How long is the ET in adults?

A

Approximately 35-38 mm

22
Q

Is it in infants or adults that the ET is more horizontal?

A

Infants

23
Q

Was is the ratio of bone vs. cartilage in the ET?

A

First 1/3 nearest the middle ear is surrounded by bone, the remaining 2/3 is surrounded by cartilage

24
Q

What is the name of the meeting point of bone and cartilage in the ET?

A

Isthmus

25
Q

Which organs in the mouth are close to the ET and involved in infection? (2)

A

Tonsil and Adenoids

26
Q

Protection against infection from nasal cavity and from loud sound of own voice is dependent on…

A

on proper closing of ET

27
Q

Pathway for cleaning debris through mucociliary transportation from the ET dependent on…

A

ET open

28
Q

Balancing air pressure of the ET is dependent on…

A

proper opening of ET

29
Q

At rest, the ET is normally…

A

closed

30
Q

Which muscle in the soft palate needs to be activated for cartilage to uncurl and the ET to open?

A

Tensor Palatini

31
Q

What actions can cause the tensor palatini activate?

A

Yawning and Swallowing

32
Q

What can happen if the ET fails to open properly?

A

Build up of negative pressure in ME

33
Q

When do we need air balancing via ET? (2)

A

Environmental changes: external air pressure change.
Metabolic reason: if ET does not open for long time, negative pressure will build up in ME.

34
Q

How many minutes a day does the ET open approximately?

A

3-4 min/day

35
Q

What can occur with the pars flaccida if there is negative pressure in the ME?

A

Pars flaccida can distort because of its higher flexibility

36
Q

What can we insert in the ME through the TM to balance air pressure?

A

Pressure Equalizing Tube

37
Q

True or False: When air pressure is BALANCED, the ET can be OPEN more easily, thereby allowing the waste to move out

A

True

38
Q

True or False: ET is opened most of the time?

A

False it’s closed

39
Q

True or False: ET closing is passively maintained?

A

True

40
Q

True or False: Closing can be interrupted by pathology

A

True

41
Q

True or False: SHORT-TERM opening causes problems of ME.

A

FALSE long-term

42
Q

How would you describe the location of the ET relative to the ME?

A

The ET runs from anterior wall of ME to posterior wall of nasopharynx

43
Q

What condition occurs as a result of negative pressure?

A

Accute Otitis Media

44
Q

True or False: Pressure Equalizing Tubes eventually fall out on their own.

A

True

45
Q

For membrane buckling, where does the tympanic membrane curve?

A

TM curves from its edges to its attachment at the manubrium.

46
Q

What is meant by middle ear transfer function?

A

Shows the gain through the middle ear across frequencies

47
Q

For the lever mechanism, greater distance = _________ force

A

smaller force

48
Q

For the lever mechanism,
smaller distance = _________ force

A

greater force

49
Q

What is the total gain of the 3 ME actions and their start and end point?

A

33.5 dB from the TM to the oval window

50
Q

What does the MEMR stands for ?

A

Middle Ear Muscle Reflex