Lecture 1: Auditory Tracts Flashcards

1
Q

Where do the primary afferents from the cochlear division of CN VIII enter the brainstem?

Considered 1st order neuron

A

Pontomedullary junction

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2
Q

Where do the ascending and descending bundles of primary afferent CN VIII synapse?

A
  • Ascending Bundle: Anterior subdivison of ventral cochlear nucleus
  • Descending Bundle: Posterior subdvision of ventral cochlear nucleus and dorsal cochlear nucleus
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3
Q

What is the function of the dorsal cochlear nuclei?

A
  • Identifying sound source elevation
  • Identifying complex spectral characteristics of sound
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4
Q

What is the function of the ventral cochlear nucleus?

A

Horizontal localization of sound

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5
Q

What is the function of the monaural tract?

A

Information about sounds at a single ear

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6
Q

Where are the primary cell bodies located in the monaural tracts?

A

Dorsal Cochlear Nucleus

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7
Q

Where does the monaural tract cross to the contralateral side?

A

Pons via dorsal acoustic stria

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8
Q

What are the points of synapse in the monaural tracts?

A
  1. Inferior Colliculus
  2. Medial Geniculate Nucleus
  3. Layer IV of Primary Auditory Cortex (Heschl’s Gyrus)
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9
Q

Fibers from the monaural tract travel through what part of the internal capsule to reach the primary auditory cortex?

A

Sublenticular limb of the internal capsule

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10
Q

What is the function of the binaural tract?

A

Differences between sounds at both ears

Role in localization of sound

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11
Q

What are the points of synapse of the binaural tract?

A
  1. Superior Olivary Nucleus
  2. Inferior Colliculus
  3. Medial Geniculate Nucleus
  4. Layer IV of Primary Auditory Cortex (Heschl’s Gyrus)
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12
Q

What structure does the binaural fibers pass through to reach the super olivary complex?

A

Trapezoid body in the pons

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13
Q

What is conduction deafness?

How can that occur?

A

Obstructed or altered transformation of sound external and middle ear

  • Damage/Infection to tympanic membrane
  • Damage to ossicles
  • Build up of earwax
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14
Q

What is sensorineural deafness?

How does it occur?

A

Ipsilateral deafness due to damage in the inner ear

  • Damage to cochlea
    • Hair Cells
    • Spiral Ganglion Cells
  • Damage to cochlear part of CN VIII
  • Damage to cochlear nuclei
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15
Q

What is central deafness?

What is its symptoms?

A

Theoretically not deaf but there is damage to central pathways (past superior olivary complex)

  • Cannot localize sound
  • Hard to follow conversations in noisy areas
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16
Q

What supplies the cochlea and auditory nuclei of pons and medulla?

A

Basilar Artery

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17
Q

Occlusion of what branch of the Basilar Artery will cause monaural hearing loss?

A

AICA

Can also damage Facial Nerve

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18
Q

What supplies the superior olivary complex and lateral lemniscus?

A

Short circumferential branches of Basilar Artery

19
Q

What supplies the inferior colliculus?

A

Superior Cerebellar Artery

Quadrigeminal Artery from PCA

20
Q

What supplies the medial geniculate body?

A

Thalamogeniculate Artery from PCA

21
Q

What supplies to the primary auditory and association cortices?

A

M2 segment of Middle Cerebral Artery

22
Q

What is the function of Wernicke’s area?

A

Comprehension of spoken and written language

  • Word representation
  • Word retrieval
23
Q

What is the function of Broca’s area?

A
  • Instruction for language output
  • Planning movements to produce speech
    • Articulation
  • Providing grammatical function of words
    • Syntax
24
Q

What is the function of the area analogous to Wernicke’s area?

A

Interpreting nonverbal signs from other people

  • Body language
25
Q

What is the function of the area analagous to Broca’s area?

A

Instructions for producing non-verbal communication (i.e. emotional gestures and intonation of speech)

26
Q

What fibers connect Wernicke’s and Broca’s areas?

A

Arcuate fibers (allow verbal repetition)

27
Q

What is the process to produce language?

A
  1. Primary Auditory Cortex: auditory discrimination
  2. Auditory Association Cortex: classification of sounds
  3. Wernicke’s Area: comprehension
  4. Arcuate Fibers: link Wernicke to Broca’s Area
  5. Broca’s Area: language output
  6. Sensorimotor Cortex: cortical output to speech muscles:
28
Q

What is the function of the lateral temporal cortex?

A

Semantic Knowledge: sentences will make sense

Word recognition (meaning)

29
Q

What is agnosia?

A

Inability to identify an object despite being able to perceive it

30
Q

What is auditory agnosia?

A

Inability to describe a sound that has been heard

31
Q

What has been damaged in auditory agnosia?

A

Bilateral temporal cortex in the sensory association cortex

Lesion is unimodal sensory association cortex (bilaterally)

32
Q

What is Wernicke’s aphasia?

A

Receptive or Fluent Aphasia

  • Unable to comprehend language in any form
    • Cannot write or read (can still speak)
  • Word salad: speech makes no sense
  • Not aware of their own problem
33
Q

What is Broca’s Aphasia?

A

Expressive or non-fluent aphasia

  • Loss of ability to speak fluently
    • Speech is slow, labored, poor enunciation
  • Can understand spoken and written language
  • Telegraphic Speech: nonessential words are omitted
34
Q

What area has been damaged in transcortical motor aphasia?

Is the patient fluent or nonfluent?

A

ACA-MCA border zone infarction

Nonfluent

35
Q

What area has been damaged in a transcortical sensory aphasia?

Is the patient fluent or nonfluent?

A

MCA-PCA border zone

Fluent

36
Q

What is Global Aphasia?

What can cause it?

A

Lesion of lateral sulcus: Broca’s and Wernicke’s areas damaged

  • MCA occlusion
  • Cannot speak or understand
  • Non-fluent
37
Q

What is conduction aphasia?

How does it occur?

A

Lesion to supramarginal gyrus and arcuate fasciculus

  • Fluent aphasia
    • Cannot repeat
  • Good comprehension
  • Can read but cannot write
  • Word finding difficulty
38
Q

A patient is able to tell you his history and read normally but cannot write. He is able to converse, however he is unable to repeat words you say to him. What type of aphasia is this?

A

Conduction aphasia

39
Q

What are the nonfluent aphasias?

A

Comprehension Still Intact

  • Broca’s aphasia
  • Transcortical motor aphasia

Comprehension Not Intact

  • Mixed transcortical aphasia
  • Global aphasia
40
Q

Repetition is preserved in what aphasic syndromes?

A

Transcortical motor

Transcortical sensory

Anomic Aphasia

41
Q

Which transcortical aphasia presents similar to Broca’s area?

A

Transcortical motor aphasia

42
Q

Which transcortical aphasia presents similar to Wernicke’s aphasia?

A

Transcortical Sensory Aphasia

43
Q

What is anomic aphasia?

A

Word finding difficulties