2.1 Cochlear Anatomy Flashcards

1
Q

What does the inner ear include? (2)

A

Cochlea and Vestibular apparatus

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2
Q

What is the role of the Cochlea in the IE?

A

Hearing

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3
Q

What is the role of the Vestibular apparatus in the IE?

A

Balance

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4
Q

What composes the Vestibular apparatus?(2)

A

Semicircular Canals and Vestibule (Saccule+Utricle)

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5
Q

The oval window, inlet for sound is close to which part of the IE?

A

Vestibular System

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6
Q

Which structure that is related to sound conduction is also closely located to the vestibular apparatus in the cochlea?

A

Oval Window

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7
Q

Where is the SGN located in the cochlea?

A

Hides in the Rosenthal canal

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8
Q

What is coiled around the modiolus?

A

Rosenthal canal

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9
Q

On the “snail”/cochlea, what frequencies are at the apex and what are at the base?

A

Apex = low frequencies Base = High frequencies

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10
Q

Where do high frequency spiral ganglion neurons send their axons? Where do low frequency fibers go?

A

High-f SGNs send their axon more peripherally in the trunk of auditory nerve and low frequency inside

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11
Q

Label the diagram:

A

a. Semi circular canals
b. Vestibule
c. Cochlea
d. Apex of cochlea
e. Ampullae
f. Round Window
g. Oval window

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12
Q

What can scalas be analogous to?

A

Ladder

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13
Q

How many scalas does the cochlea have?

A

3

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14
Q

What are the 3 scalas of the cochlea?

A

SV, ST, SM

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15
Q

What are the Scalas separeted by?

A

By two membranes

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16
Q

Label this diagram

A
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17
Q

What is the Helicotrema?

A

Apex of the Cochlea

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18
Q

How could you describe the spiral ganglion neurons?

A

A bunch of axons and dendrites
A group of neuron cell bodies in the modiolus, the conical central axis of the cochlea.

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19
Q

What are the two ways the 8th nerve is organized?

A

(1) frequency configuration, (2) auditory vs. vestibular

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20
Q

Where can we see the relationship across the facial, vestibular and cochlear nerve AND what else goes to the inner ear via this location?

A

In the internal auditory meatus and blood vessels to inner ear also go via IAC.

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21
Q

What is the mnemonic to remember the position of the nerves in the IAC?

A

7up Coke Down

22
Q

What is the habenula perforata and where is it?

A

Holes for the outlet of auditory nerve fibers: habenula perforata

23
Q

What can affect the spiral ganglion neuron count in the Rosenthal Canal?

A

Toxic Drugs

24
Q

What are the five main parts of the membrane labyrinth (once the bony shell is removed)

A

SV
ST
SM
BM
RM

25
Q

Which Scala have perilymph and which have endolymph?

A

SV ST Perilymph
SM Endolymph

26
Q

What is Perilymph?

A

Similar to extracellular and CSF fluid contains more Na+

27
Q

What is Endolymph?

A

Similar to intracellular fluid more K+

28
Q

What does the lateral wall of the scala media contain? (2)

A

stria vascularis and spiral ligament

29
Q

Geometrically, where does sound go before hitting the cochlea? Why do we hear sound through the cochlea?

A

sound gets into vestibule and then cochlea, why we hear sound through cochlea which all the necessary structures for hearing. The vestibule is not “built” for hearing. It’s all about the accessory structures!

30
Q

Label this diagram

A
31
Q

What is the endolymphatic sac responsible for?

A

Responsible for reabsorption of endolymph

32
Q

What are two associated conditions with the blockage of the endolymph sac?

A

May cause cochlear hydrops OR vertigo attack—Meniere’s disease (both conditions are the same thing)

33
Q

In fact the perilymph space and CSF are connected through the ______________.

A

cochlear aqueduct

34
Q

Describe how the relationship of the osseous spiral lamina and basilar membrane changes from the base to the apex?

A

BM is narrower at the base, increasing toward the apex.
OSL wider at the base, and narrower at the apex.

35
Q

Describe the impedance components and its relation to the frequency of sound in relation to the width of the basilar membrane.

A

There are different resonant frequencies throughout the cochlea due to gradients of the BM. The mass and stiffness components change with the width of the BM.
The shifting of the BM width is important for frequency analysis. The narrower the BM, the better response to higher frequencies (i.e., at the base). The apex is responsible for low frequency sound (wider).

36
Q

Different resonant frequencies throughout the cochlea due to __________ of the BM.

A

gradients

37
Q

Which volume is larger, the scala vestibuli or the scala tympani? What is one reason for this?

A

Volume of SV is slightly larger than ST, partially because it is connected to the vestibule.

38
Q

What is another way to describe the ‘up and down’ movement of the basilar membrane? What does this do?

A

It’s the effective vibration of the BM. It helps balance pressure.

39
Q

What happens to acoustic force as it goes into the cochlea at the oval window?

A

It causes the BM to vibrate, and it becomes partially released through the round window.

40
Q

What causes the pressures imbalance?

A

Acoustic Energy doesn’t fully get released at the round window due to the different dimensions between the SV and the ST as well as the different flexibilities between the OW and RW (the RW is more flexible)

41
Q

How does the vibration of the basilar membrane compare to that of the bone vibration and osseous spiral lamina in sound conduction?

A

The BM vibrates more than the bone vibration as well as the osseous spiral lamina.

42
Q

Where is the Organ of Corti located?

A

It’s on the basilar membrane

43
Q

Describe the resonant frequencies of the cochlea? What is the reason?

A

The resonant frequencies of the cochlea change along the BM.
Base = Greater response to higher frequencies and the BM is narrower
Apex = Greater response to lower frequencies because the BM is wider.

44
Q

What are the two main (big) categories of cochlear cells

A

Hair cells and supporting cells.

45
Q

What are the hair cells in the IE? How many rows do they have?

A

There are inner hair cells and outer hair cells. IHCs have one row, OHCs have three rows.

46
Q

What are four examples of the supporting cells?

A

Pillar cells, Deiter cells, sulcus cells and Henson’s cells

47
Q

What are the two other cells except the hair cells and supporting cells?

A

Claudius C, fibrocytos

48
Q

True or False: We can find supporting cells around the bodies of IHC?

A

True

49
Q

True or False: We can find supporting cells around the bodies of OHC?

A

False

50
Q

How many OHC do we have in one ear?

A

12000

51
Q

How many IHC do we have on average in one ear?

A

3500

52
Q

What is the limbus and where is it located?

A

It is a periosteum layer on the OSL connected to the TM (provides blood, nerves and cells to help bones grow.