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Neuroscience Exam 3 > Hearing/audition & vestibular system > Flashcards

Hearing/audition & vestibular system Flashcards

1
Q

external ear structures

A

pinna and external auditory meatus

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2
Q

external ear function

A

collect sound waves and serves as a resonator

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3
Q

middle ear structures

A

ossicles: malleus, incus, stapes
structures: stapedius (stapes), tensor tympani (malleus)
eustachian tube: opens into middle ear, joints it to pharynx

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4
Q

middle ear functions

A
  • efficient transmission of sound travelling in air to the fluid filled inner ear
  • reflexively control the ossicular movements during loud noises
  • adjust for pressure variations
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5
Q

inner ear structures

A

bony labyrinth

membranous labyrinth: cochlea, scala, media, tympani, vestiboli, oval and round windows, organ of corti

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6
Q

inner ear functions

A

Transform sound vibrations in fluid filled canals to neural impulses which travel in CNVIII towards CNS

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7
Q

function of stapedius and tensor tympani

A

Contract in response to a loud noise to decrease the movement of the ossicles to dampen the loud noise

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8
Q

clinical effects if stapedius and tensor tympani are weak

A

Damage = certain loud noises that are louder than normal; may also report having difficulty understanding speech when these muscles are paralyzed

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9
Q

pathway for sound from the receptor to the primary auditory cortex

RECEPTOR/1st ORDER

A

Receptor: hair cells in scala media
1st Order:
Bipolar cells → hair cells → vestibulocochlear nerve → brainstem → 2nd order neurons in cochlear nuclei

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10
Q

pathway for sound from the receptor to the primary auditory cortex

CENTRAL PATHWAYS/2nd ORDER

A

2 routes:

  1. Directly to inferior colliculus (midbrain)
    - turn head in response to sound; reflexive or autonomic
  2. Goes to superior olivary nucleus (pons)
    - perception of sound
    - goes up bilaterally and up lateral lemniscus
    - terminates in medial geniculate nucleus (thalamus)
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11
Q

pathway for sound from the receptor to the primary auditory cortex

REFLEX PATHWAYS

A

Inferior colliculi (midbrain) and superior olivary nucleus send info to: superior collicluli, medial longidituinal fasciclus, vestibular nuclei, and SC to coordinate head/eye movements toward sound and to CN VII to blink

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12
Q

pathway for sound from the receptor to the primary auditory cortex

DESCENDING PATHWAYS

A

Provide feedback circuits to sharpen auditory signals and enhance sound localization by suppressing competing signals

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13
Q

pathway for sound from the receptor to the primary auditory cortex

BILATERAL REPRESENTATION

A

receives info from both ears
More connections from opposite ear than from ipsilateral ear
lesion in cortex will not result in deafness in contralateral ear because of this

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14
Q

function of superior olivary nucleus

A
  • Receives binaural convergence into single neurons and this allows for the timing of input from one ear to be compared to the other.
  • Destruction of this nucleus produces difficulties with localization of sound
  • Coordinate reflexive movements of head and eyes towards sound!
  • CN VII-causes you to blink in response to sound!
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15
Q

lesions of outer and middle ear

A

mild hearing loss in ipsilateral ear (conductive loss)

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16
Q

lesions of inner ear

A

CNVIII, cochlear nuclei: significant hearing loss on ipsilateral side (sensorineural hearing loss)

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17
Q

lesions of superior olivary nucleus

A

after SON: may not notice because bilateral

before SON: may have unilateral deficits

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18
Q

bilateral lesions in the cortex or brainstem affecting the nuclei or tracts

A

can cause bilateral hearing impairments that can be severe

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19
Q

Otitis Media

A

(middle ear infection) = most common cause of conductive hearing loss
Common problem in children; if chronic and not treated, may affected speech and language development

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20
Q

Most common cause of sensorineural hearing loss is

A

exposure to loud noise that damages the hair cells

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21
Q

Other causes of sensorineural hearing loss include

A

Meniere’s disease and Acoustic neuroma

22
Q

Meniere’s disease

A

progressive deafness, tinnitus, and dizziness

motion sickness

23
Q

Acoustic Neuroma

A

tumor affecting CN VII and CN VIII at cerebellopontine angle

24
Q

blood supply to inner ear and lesion

A

Labyrinthine arteries: interruption of blood supply will affect structures in the inner ear (sensorineural hearing loss)

25
Q

what does the peripheral sensory apparatus consist of and where does it lie

A

Consists of bony labyrinth and membranous labyrinth

Lies in inner ear

26
Q

components of membranous labyrinth

A

lies w/in bony labyrinth; contains cochlea (hearing) and vestibular apparatus (vestibular functions)

27
Q

components of vestibular apparatus

A

3 semicircular canals, the utricle, and the saccule

28
Q

which 2 vestibular components are referred to as the otoliths

A

utricle and saccule (in vestibule)

29
Q

how the otoliths sits

A 
Maculae (hair cells) sit on specialized structures
Saccule – sit on vertical plane 
 sacs sit upright = vertical
Utricle – sit on horizontal plane 
 U = urn = dead = horizontal
30
Q

how is the otoliths stimulated

A

Otolithic membranes contain calcium carbonate crystals called otoconia that overlie maculae
Movements of membranes cause bending of sensory hair cells and subsequent firing of vestibular nerve fibers

31
Q

function of otoliths

A

Register forces related to linear acceleration in anterior-posterior, lateral, or occipito-caudal direction
Register static head position with respect to gravity
Regulate static equilibrium

32
Q

orientation of semicircular canals

A

Each canal plane is perpendicular to the others

33
Q

how pairs of canals function together

A

The 6 individual semicircular canals together become 3 coplanar pairs
Anterior canal on right operates with posterior canal on left
Posterior canal on right functions with anterior canal on left
2 horizontal canals operate together
When angular head motion occurs within shared plane, neural firing increases in vestibular nerve on one side and decreases in other
This push/pull allows CNS to detect direction of rotation

34
Q

function of otoliths

A

register forces related to linear acceleration in anterior-posterior, lateral, or occipito-caudal direction.
They also register static head position with respect to gravity (regulate static equilibrium)

35
Q

function of semicircular canals

A

Each pair responds selectively to angular/rotational motion in a particular direction
they are also responsible for detecting the velocity of head movements which enables individuals to generate eye movement that matches the velocity of head movements

36
Q

pathway from receptor cells to the vestibular nuclei

A

1st order (bipolar) = Scarpa’s ganglion in internal auditory meatus

central processes travel in CN VIII, leaves internal auditory meatus, enter brainstem at pontomedullary junction

go directly to cerebellum through inferior cerebellar peduncle without synapsing
go to vestibular nuclei located in the lateral aspect of the pons and medulla

37
Q

cerebellum

A

coordinates balance responses

38
Q

Spinal cord via lateral vestibulospinal tracts

A

activate postural response

39
Q

Spinal cord via medial vestibulospinal tract

A

for head righting reactions

40
Q

Spinal cord via reticulospinal tracts

A

balance reactions

41
Q

Motor nuclei of extraocular muscles via medial longitudinal fasciculus

A

coordination of head and eye movements and reflexive eye movements (vestibule-ocular reflex)

42
Q

cortex

A

conscious perception of balance

43
Q

reticular system and ANS

A

nausea

44
Q

purpose of Vestibuloocular Reflex (VOR)

A

Motor response that generates eye movements to enable clear vision while the head is in motion

45
Q

purpose of Vestibulospinal Reflex (VSR)

A

Motor response that generates compensatory body movement to maintain head and postural stability and to prevent falls slippery fall

46
Q

nystagmus

A

normal reflexive rhythmic movement of eyeballs in response to either head rotation or visual fixation on a moving object

47
Q

2 phases of nystagmus

A

Slow Phase: eyes slowly drift away from center field of vision
Fast phase: eyes suddenly return to central field of vision

48
Q

stimulation of nystagmus

A

Normally stimulated by vestibular stimulation, visual (optokinetic) stimulation, or extreme lateral gaze: short duration
Professional skaters and ballet dancers can inhibit with visual feedback

49
Q

pathologic nystagmus

A

abnormal nystagmus that is present at rest, with minimal stimulation, or that lasts excessively long after stimulation
Abnormal response: may be spontaneous, positional, or gaze evoked
Often a cardinal sign of vestibular dysfunction

50
Q

lesion to CN VIII or damage to inner ear

A

Balance dysfunction, abnormal VOR and VSR, abnormal nystagmus, nausea, vertigo

51
Q

lesion of vestibular nuclei

A

Balance dysfunction, abnormal VOR and VSR, abnormal nystagmus, nausea, vertigo AND motor issues

52
Q

Benign paraoxysmal positional vertigo

A

sudden false sensation that you’re spinning, intense dizziness
triggered by certain head positions or movements; caused by otoconia that are dislodged in fluid-filled semicircular canals (interfere with normal fluid movement, causes inner ear to send false signals to brain)

Neuroscience Exam 3 (6 decks)

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