Test 2: Auditory Pathway Flashcards

1
Q

What CN is responsible for hearing and how does it happen?

A

Cochlear nerve CN VIII
-one of two nerves from CNVIII

Audition transduced by mechanoreceptors in cochlea

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2
Q

What are the two primary pathways roles?

A

Detect sound in space

Localize sound in space

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3
Q

What are the features of the inner ear vs. middle ear?

A

Middle ear:

  • starts at tympanic membrane
  • stapes, maleus, incus for amplification
  • lesions=conductive hearing loss

Inner ear:

  • starts at oval window (base of stapes)
  • cochlea
  • lesions=senorineural hearing loss
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4
Q

What are the initial receptors of auditory pathways

A

mechannoreceptors in cochlea

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5
Q

What are the 3 champers of the cochlea

A
  1. Scala media:
    - fluid high in K; influx causes depolarization
    - in organ of corti- sensory neuron 1CB
  2. Scala vestibule:
    - superior compartment
    - perilymph
  3. Scala tymponi:
    - inferior compartment
    - perilymph
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6
Q

What does perilymph in scala vestibule and tymponi do?

A

waves ossilate the basilar membrane
bends hair cells
starts transduction

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7
Q

What do the inner hair cells do?

A

On organ of corti- basilar membrane

  • cilia imbedded in tectoral membrane that forms roof
  • synapse on cochlear neurons
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8
Q

How do the sound waves go through the middle ear?

A

enter auditory canal of middle ear-> deflect tympanic membrane -> mobilzie small bones to amplify
MECHANICAL energy

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9
Q

How do sound waves transduce in the inner ear?

A

Sound waves into fluid wave in perilymph
deflects basilar membrain -> shear force bends tectoral hair cells
Bending hair cells-> midifies voltage -> depolarize BIPOLAR COCHLEAR NEURONS

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10
Q

What are the characteristics of 1 neurons?

A

Cochlear sensory neurons from CNVIII
CB in cochlear spinal ganglion
-transmit auditory signals to dorsal/ventral cochlear nerve
-pontemedullary junction in cerebellar peduncles

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11
Q

What is the difference in mechanical vs. electrical transduction?

A

Electrical: ossilation of basilar membrain and sterocillia in tectoral

Mechanical: fluid waves press stereocil into tectoral membrane- bends hair calls

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12
Q

What is the totonic map in the cochlea?

A

High frequency sounds hear close to oval window- more by middle ear

Low frequency sounds hear deeper by apex

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13
Q

How many neurons make up the most direct auditory pathway?

A

4

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14
Q

Where are the 2CB

A

Ventral or dorsal nuclei depending on sound frequency

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15
Q

What do the ventral cochlear nuclei neurons do

A

Contribute to horizontal path for LOCALIZATION

  • relay bilaterally for redundancy
  • ascend superior olives
  • some decussate in basis pons in trapezoid body
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16
Q

What occurs at the level of the superior olives in the ventral pathway?

A

L/R comparison, timing, and amplitude

-project bilaterally

17
Q

What do the dorsal cochlear nuclei neurons do

A

decussate in pons

PERCEPTION of sound

18
Q

Both ventral and dorsal nuclei ascent in what tract?

A

Lateral leminiscus tract

-go to inferior colliculi to combine with other auditory input: reflexes, bilateral communication

19
Q

Where are the 3CB

A

Inferior colliculous

-ascend in Brachium of inferiour colliculs to MGN

20
Q

Where are 4CB

A

MGN thalamus

-form auditory radiations. go through posterior limb to A1

21
Q

What is the difference between A1 and A2

A

1: concious detection of initial states of sound analysis
2: higher cortexes of receptive language/recognition in wernickes-BA22

22
Q

What makes up the primary auditory cortex

A

transverse temporal gyrus

superior tempoeral gyrus

23
Q

Where are different pitches heard

A

High hz/pitch deeper in cortex

Low hz/pitch more lateral in cortez

24
Q

What is the BA number for A1

A

41

25
Q

What neurons are traveling in the lateral lemniscal tract?

A

DGN to L/R superior olives

26
Q

What neurons are traveling in the brachium of inferior colliculus

A

Inferior colliculous CB to MGN

27
Q

What jobs do arcuate vs uncinate fasciulus do?

A

arcuate: where? spacial
uncinate: what? language

28
Q

What blood supply feeds the cochlear nerve (caudal pons)

A

AICA

29
Q

What supplys the medulla

A

vertebral- most

PICA- rostral

30
Q

What supplies the caudal pons

A

Basilar- most

AICE- caudal

31
Q

What supplies the rostral pons

A

basilar-most

-SCA dorsal

32
Q

What supplies the caudal midbrain

A

basilar

-SCA and PCA

33
Q

What supplies the rostral midbrain

A

PCA-most

Post comm, basilar, SCA

34
Q

What supplies the MGM and auditory radiations?

A

Ant choiroidal: internal capsule
PCA: MGN and LGN
MCA: A1