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BRS YEAR 2 > Auditory And Vestubukar System > Flashcards

Auditory And Vestubukar System Flashcards

1
Q

Difference between vestibular and auditory sensory systems

A

vestibular senses low frequency (=movement) and auditory senses high frequency (=sound)

  • amplitude (volume → dB) & frequency (pitch → Hz)
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2
Q

two relevant measurements for sound?

A

amplitude (volume → dB):sound,pressure,subjective attribute correlated with physical strength & frequency (pitch → Hz)cycles per second,perceived tone

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3
Q

human range for hearing in each of these parameters?

A

20-20000 Hz, 0-120 dB

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4
Q

outer ear functions?

A

capture sound

focus onto tympanic membrane

approx 10 dB amplification of upper range frequencies

protect from external threats

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5
Q

middle ear function?

A

mechanical amplification (20-30 dB)

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6
Q

inner ear function?

A

transduce vibration into nervous impulses
Cochlea
Captured rhe frequency and intensity of sound

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7
Q

three compartments of the cochlea?

A

scala vestibuli → vestibular membrane → scala media → basilar membrane → scala tympani

Scala vestibuli and scala tympani are bone structures which contain peri lymph (high in sodium). Scala mediated is the membranous structure which contains endolymph (high in potassium). Here is where the hearing organ of corti is

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8
Q

what are each filled with? key ingredient in these fillings?

A

scala vestibuli and tympani → perilymph (high in Na+)

scala media → endolymph (high in K+)

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9
Q

what are each made of?

A

vestibuli and tympani → bony structures

media → membranous structure with hearing organ (organ of Corti)

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10
Q

where is the organ of Corti and how is it organized

A

Basilar membrane
Like a xylophone (tonitopically)

narrow and tight base for high frequency, wide and loose apex for low frequency

hair cells pick up signals

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11
Q

cell types within the organ of corti

A

Inner hair cells and outer hair cells

IHCs carry most auditory nerve afferent information → transduction of sound

OHCs carry most auditory nerve efferent information → modulation of response sensitivity

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12
Q

how does cell depolarisation occur?

A

tectorial membrane above hair cells causes cell deflection

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13
Q

hairs of the hair cells are called what?

A

Stereocillia

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14
Q

What does the hair cells deflection do

A

deflection towards the longest cilium (kinocilium) opens K+ channels

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15
Q

Effect of hair cells and outer deflection

A

cell depolarisation and subsequent vestibulocochlear nerve depolarisation

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16
Q

what do higher amplitudes do?

A

cause greater deflection of the stereocilia → more K+ channels open → stronger signalling

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17
Q

deflection in the other direction causes what?

A

closing K+ channels → hyperpolarisation

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18
Q

vestibulocochlear nerve goes where after cochlea? And what happens next

A

ipsilateral cochlear nuclei in pons
Superior olive
Inferior colliculus
Medial geniculate body
Auditory cortex

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19
Q

what happens at the level of the superior olive?

A

some auditory information crossing to the other side → bilateral from this point

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20
Q
  • types of hearing loss (anatomical distinction)? associated with issue where?
    -
A
  • conductive hearing loss?outer or middle ear
  • sensorineural hearing loss (most common)?cochlea or auditory nerve
  • central hearing loss?rare, brain/brainstem issue
21
Q

types of hearing loss (onset distinction)?

A

sudden hearing loss (minutes to days)

progressive hearing loss (months to years)

22
Q

causes of conductive hearing loss in (open):

A
  • outer earforeign body, earwax
  • middle earotitis, otosclerosis
23
Q

causes of sensorineural hearing loss in (open):

A
  • inner earnoisepresbycusis (old age degeneration)ototoxicity
  • auditory nerveacoustic neuroma (vestibular schwannoma) → unilateral
24
Q
  • tuning fork tests to assess gross hearing loss?
A

weber test (on skull) and rinne test (next to ear/on mastoid process)

25
Q
  • audiometry signs of conductive/sensorineural hearing loss?
A

conductive: air conduction hearing much worse than bone conduction

sensorineural: air and bone same, hearing inconsistent between frequencies (some are weaker than others)
a normal threshold is between 0-20dB

26
Q

what are OAEs?

A

otoacoustic emissions → normal sounds produced by cochlea used in newborn hearing screening

27
Q

treatments for hearing loss?

A

address underlying cause, use hearing aids, cochlear implants and brainstem implants

28
Q

vestibular system input and output?

A

input: movement and gravity

output: postural control and ocular reflex

29
Q

what is the vestibule made up of?

A

utricle and saccule
These are otolith organs

30
Q

what else makes up the vestibular system?

A

three semicircular canals: anterior, posterior, lateral

  • utricle
    Comnected to ampulla where hair cells sit
31
Q
  • what do the maculae in the utricle and saccule contain?
A

hair cells, gelatinous matrix, otoliths (carbonate crystals)

32
Q

what is the orientation in each organ?

A

horizontally placed in utricle thus detects horizontal movement, vertically placed in saccule thus detects vertical movement

33
Q

what do the semicircular canals contain?

A

ampulla contains crista and hair cells, surrounded by cupula to help with movement

rest of canal has endolymph → high in K+

34
Q
  • hair cell resting activity in terms of neural signalling?
A

they have a basal discharge rate to the nerve

increased by movement of stereocilia toward kinocilium → depolarisation

decreased by movement of stereocilia away from kinocilium → hyperpolarisation

35
Q

vestibular nerve primary afferents synapse where?

A

vestibular nuclei in brainstem (pons)

36
Q

what are the two main vestibular reflexes?

A

vestibulo-ocular reflex and vestibulospinal reflex

37
Q

what does VOR do?

A

Keeps images fixed in retina

38
Q

by what mechanism does vor workers

A

vestibular nuclei connected to oculomotor nuclei

eye movement in opposite direction to head movement but same velocity and amplitude

39
Q

different types of vestibular disorder → how to categorise?

A

timing (acute/slow onset) and laterality

40
Q

characteristics of each disorder

A

acute unilateral main complaints are dizziness, vertigo, nausea, imbalance

slow onset unilateral / any bilateral → main complaints are imbalance and nausea with no vertigo

41
Q

can also be characterised by location into what? (VD)

A

peripheral (vestibular organ or vestibulocochlear nerve)

central (brainstem/cerebellum)

Eg peripheral: vestibular neuritis, benign paroxysmal positional vertigo (BPPV), meniere’s disease

central: stroke, multiple sclerosis, tumours

42
Q

core examination areas for vestibular disease?

A

Ear eyes legs

43
Q

red flag symptoms? For vd

A

headache, gait problems, hyper-acute onset, hearing loss, prolonged symptoms (>4 days)

44
Q

Exam for acute and intermittent

A
  • acute → vestibular neuritis, strokeHINTS exam
  • what is this?head impulse test (horizontal rotational VOR → abnormal usually indicates peripheral issue)nystagmus (repetitive uncontrolled eye movements)test of skew deviation (vertical ocular misalignment → usually absent for peripheral diseases, done by alternate cover test)
  • intermittent → BPPVDix-Hallpike test
45
Q

BPPV pathology?

A

vertigo on certain maneuvers caused by displaced otolith crystals.
Fixed by epley maneuver
Dix hallpike manouver can help identify

46
Q

Semi circular canal planes

A

Anterior and posterior canals form a 90 degree angle
Lateral canals are horizontal to other canals so work in pairs

47
Q

Vestibular neuritis

A

Nause and vomiting
Severe vertigo
Nystagmus

Usually due to heroes,epstein barr and influenza virus

Occurs as attacks

48
Q

Ménière’s disease

A

Fullness and pressure in ear
Hearing loss
Vertigo
May be due to genetic migraines etc

49
Q

Nystagmus

A

Slow phase is where eyes start drifting of away from focus of object
Fast phase is where eyes correct themselves back to original position
Nystagmus named after direction of fast phase

BRS YEAR 2 (43 decks)

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