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MS2 - Nervous System > Auditory I, II, and III > Flashcards

Auditory I, II, and III Flashcards

1
Q

Sound pressure level is equal to ___________.

A

20 x log([pressure]/[pressure reference])

Where P(ref) = 20 micro Pascals

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2
Q

We typically lose ________ frequency hearing first.

A

high

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3
Q

The body of the ear (that helps catch and direct sound waves) is called the __________.

A

pinna

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4
Q

The bones of the middle ear, from outside to inside, are ______________.

A

malleus, incus, and stapes

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5
Q

A static pressure difference between the middle ear and the external auditory meatus will lead to what kind of hearing loss?

A

Conductance

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6
Q

Roughly 99.9% of the acoustic energy from sound is deflected by the ear. Why?

A

Sound “does not like” to pass from air to water due to impedance mismatch, and thus most sound ricochets off.

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7
Q

How is the initial attenuation of sound energy overcome?

A

The tympanic membrane is a fluid-filled sac with a surface area of 60 mm^2. It narrows to a point on the malleus that is 3 mm^2, thus amplifying the pressure (because pressure = force / area).

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8
Q

What is the size of the cochlea?

A

About the size of a chickpea

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9
Q

What are the three chambers of the cochlea?

A

Scala vestibuli
Scala media
Scala tympani

Though it’s easier to think of just the vestibuli and the tympani separated by the basilar membrane.

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10
Q

There are two ends of the cochlear: the base and the apex. Where does the stapes contact?

A

The base (at the oval window)

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11
Q

Describe the changes in the basilar membrane from base to apex.

A

The base –where the stapes vibrates – is narrower and tighter and conducts higher frequencies, while the apex is wider and “floppier” and conducts lower frequencies.

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12
Q

What happens at the round window when the oval window is pressed?

A

It presses out –like a release valve

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13
Q

The hole at the end of the basilar membrane is the _______________; it connects which two cavities?

A

helicotrema; scala vestibuli and scala tympani

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14
Q

Endolymph is the fluid in the ____________ (apical side of hair cells). What is its composition? What structure mediates this?

A

scala media; high potassium, low sodium; stria vasularis

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15
Q

Perilymph is the fluid in the ______________ (basilar side of hair cells). What is its composition?

A

scala tympani; low potassium, high sodium

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16
Q

The stereocilia are connected by ___________.

A

tip links

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17
Q

The stereocilia of the outer hair cells are embedded in the ___________.

A

tectorial membrane

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18
Q

What diuretic can “completely wipe out” your outer hair cells?

A

Furosemide –leading to a 60 dB sensorineural hearing loss

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19
Q

The outer hair cells function as a __________.

A

cochlear amplifier

20
Q

Each cochlea contains how many hair cells?

A

16,000

3,500 inner hair cells
12,500 outer hair cells

21
Q

How many auditory nerve fibers connect to each ear?

A

30,000

Type I: 28,500 (connect to inner)
Type II: 1,500 (connect to outer)

22
Q

True or false: one inner hair cell can connect to many auditory nerve fibers.

A

True

23
Q

Type II nerve fibers connect to how many outer hair cells?

A

Lots! There are only 1,500 type II fibers, yet there are 12,500 outer hair cells!

24
Q

How do hair cells react to stimulation?

A

They depolarize by the influx of potassium from the unique endolymph.

25
Q

True or false: the area immediately surrounding the ossicles is fluid-filled.

A

False. This area is air-filled –which is which changes in air pressure lead to conductance loss.

26
Q

The mapping of sounds onto the basilar membrane is called _____________.

A

tonotopy

27
Q

High frequency hearing is lost first by noise-induced damage to the ____________.

A

stereociliated cells in the organ of Corti

28
Q

What physical exam sign suggests conductive hearing loss?

A

The patient can hear the sound of a struck tuning fork better when pressed to their mastoid process (as compared to through air). Sensorineural hearing loss would present as the opposite.

29
Q

What are ITDs and ILDs?

A

Interaural time differences and interaural level differences

30
Q

Interaural level differences are only used in distinguishing ____________. ITDs are used in distinguishing ____________.

A

high-frequency sounds; low frequency sounds

31
Q

The primary auditory cortex and secondary auditory cortex are which Brodmann areas?

A

41 and 42 – both of which are in the posterior section of the lateral fissure

32
Q

Brodmann’s areas 44 and 45 are __________.

A

Broca’s area

33
Q

Which part of the brain is Wernicke’s area?

A

posterior temporal lobe (Brodmann 22)

34
Q

Describe otosclerosis.

A

Arthritic bone growth in the middle ear impedes the movement of the ossicles, resulting in conductive hearing loss

35
Q

Sitting within the ____________ and on top of the ____________ is the organ of corti.

A

scala media; basilar membrane

36
Q

The oval window bulges (during compression) into the scala ____________.

A

vestibuli

37
Q

There are three rows of ____________ hair cells and one row of ___________.

A

outer; inner hair cells

38
Q

There are how many hair cells per cochlea?

A

16,000

39
Q

A collapse of the endocochlear potential (for potassium) results in _______________.

A

sensorineural deafness

40
Q

True or false: unilateral lesions to the auditory tracts rostral to the mid pons produce unilateral deafness.

A

False. Some axons branch bilaterally in the mid pons (after the superior olivary nucleus), so unilateral lesions will not lead to unilateral deafness.

41
Q

From the inferior colliculus, fibers project mainly to the _____________.

A

ipsilateral medial geniculate

42
Q

The medial geniculate projects fibers to the _____________.

A

primary auditory cortex (in the superior temporal gyrus)

43
Q

The inferior colliculus brings together auditory impulses from the ____________ side of the body.

A

contralateral

44
Q

Neurons exhibit phase locking to _________ frequency sounds.

A

low

45
Q

Spectral cues are only for sounds greater than __________ kHz.

A

5

46
Q

The “coincidence mismatch” system occurs in the ___________.

A

medial superior olive

MS2 - Nervous System (111 decks)

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