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Flashcards in Special Senses 1 Deck (62):
1

What is the equation for the speed of sound?

m/sec = (wavelength)*(frequency)

2

High frequency sound has short or long wavelength?

short

[m/sec = (wavelength)*(frequency)]

3

What determines the intensity of sound?

The amplitude

4

What is the basis for sound?

Movement of air molecules

5

True of false: loudness can be measured by machines?

False--only amplitude

6

What does loudness depend on?

Both frequency and sound pressure

7

What is the equation for sound level pressure (dB)?

20log(P/Pr): P=sound pressure, Pr=reference pressure

8

What is the range of human hearing (in Hz)?

20 Hz to 20,000 Hz

9

What is the range of frequencies over which we hear best?

1-4 kHz

10

What can cause a notching an audiogram?

Killing hair cells = loss of hearing range

11

What are the two factors that can determine hearing loss?

How loud
How long

12

What is the purpose of the pinna?

Localizing sound in the vertical plane

13

The external auditory meatus has a resonant frequency of what? What is the purpose of this?

3,500 Hz--this increases sound pressure at the TM

14

What is the purpose of the Eustachian tube?

Equalize pressure in the middle ear with outside environment

15

What is the main function of the ossicular system?

Provides impedance match between outer and inner ear

16

What are the two muscles in the middle ear, and what is their innervation?

Stapedius -- CN VII
Tensor tympani-- CN V

17

Which is window that receive input from the stapes: the oval or the round? What is the other used for?

Oval

Round is for pressure balance

18

What is the sensory input to the middle ear attenuation reflex?

CN VIII

19

What is the motor output of the attenuation reflex?

CN VII to stap
CN V to tensor TM

20

What is the effect of Bell's palsy on the attenuation reflex?

Loss of CN VII efferent to stapedius causing hyperacusis

21

Is Bell's palsy a LMN or UMN problem?

LMN of CN VII

22

What is the treatment for Bell's palsy?

Steroids to prevent swelling from CN VII

23

When do the middle ear muscles (stapedius and tensor tympani) contract regularly?

During speaking

24

What is the small coiled structure in the ear that contains the organ of Corti?

Cochlea

25

What is endolymph? What ion is found in high concentration here?

Fluid in the cochlea

K

26

What is perilymph? What ion is found in high concentration here?

Fluid in scala vestibuli and scala tympani

Na high, (K low)

27

What are the spaces found around the scala media? (above and below)

Above = scala vestibuli
Below = Scala tympani

28

What is the fluid the contacts the top of the hair cells? Bottom?

Top = endolymph
Bottom = perilymph

29

What is the structure that produces endolymph in the scala media?

Stria vascularis

30

What is the effect of some diuretics on the ear?

Damage the stria vascularis

31

Failure of what cells to move into the ear can cause hearing loss?

Melanocytes

32

What is the layer of fluid that lies over the hair cells?

Tectorial membrane

33

What are the hair cell names that sit below the tectorial membrane?

Stereocilia

34

How many afferent nerves are there per hair cell?

One afferent fiber innervates just one hair cell but several fibers might synapse with one hair cell.

35

What is the function of the inner hair cells?

Actual sensory receptor

36

What is the purpose of the high [K] in the scala media endolymph?

Allows for ion gradient so flow into the hair cells

37

Why does a hereditary problem with gap junctions cause hearing loss?

Loss of feedback of K+ from the hair cells to the stria vascularis

38

What is the function of the outer hair cells?

Contract and expand the tectorial to sharpen frequency resolving power

39

What is the origin of the olivocochlear bundle?

Superior olivary nucleus

40

What is the helicotrema?

End of the cochlea where sound waves turn around

41

What is the relationship between increasing Hz and the distance from the stapes?

Higher Hz means peak the most movement of the basilar membrane occur at lower distance

42

What is the tonotopic map?

Different points along the cochlea are used to detect different frequency sounds

43

High frequencies occur where in the cochlea?

Early--near the stapes

44

Low frequencies occur where in the cochlea?

Near apex of the cochlea

45

Where in the brainstem is the CN VIII nucleus?

Posterior medulla

46

What structure in the pons does the cochlear fibers go (some cross over) to?

Superior olive

47

Where do fibers from the cochlear nucleus go after they (cross over) in the pons at the superior olive? (3)

Lateral lemniscus, then inferior colliculus, then medial geniculate complex

48

Does frequency map in the auditory cortex

Yes

49

How are sounds localized?

auditory neurons compare loudness of sound arriving in each ear, or the arrival of the sound

50

What is the structure in the brainstem responsible for the reflex of the eyes and hearing?

Colliculus

51

What is the structure in the brainstem that is utilized in localizing sound?

Superior olive

52

What is the cause of conductive deafness?

impaired sound transmission in the external or middle ear

53

What is otosclerosis?

Genetic disease where bone is deposited around the stapes

54

True or false: OM with effusion can cause conductive hearing loss

True

55

What is the problem with conductive hearing loss early in life?

Inability to distinguish between sounds hinders language development

56

What is the disease associated with vestibular Schwanomas (acoustic neuromas)

NFM II

57

What is Meniere's syndrome?

Overproduction of endolymph

58

What is the cause of central hearing loss?

Lesions to central auditory nuclei and pathways

59

Why is it that unilateral damage to ascending auditory pathways has only subtle effects on hearing?

So much crossing

60

What is the disease that can cause defective sound localization?

MS

61

True or false: humans emit tones from their ears

True

62

What is the clinical application of otoacoustic emissions?

screening tool since patients with sensory hearing losses of greater than 30 dB do not usually have these emissions.