Auditory Pathways

Question 1

What is the primary afferent of the auditory pathway?

Answer 1

CN VIII - cochlear part

Question 2

Where are the cell bodies of the cochlear nerve?

Answer 2

Spiral ganglion

Question 3

Where does CN 8 go after leaving the spiral ganglion?

Answer 3

Enters the brainstem at pontomedullary junction - divides into ascending and descending bundles

Synapses at cochlear nuclei

Question 4

At the cochlear nuclei, where do the ascending and descending bundles synapse?

Answer 4

Ascending bundles:
Anterior division of ventral cochlear nucleus

Descending bundles:
Posterior division of ventral cochlear nucleus
Dorsal cochlear nucleus

Question 5

What does the dorsal cochlear nucleus identify?

Answer 5

Identifies sound elevation

Identifies complex characteristics of sounds

Question 6

What is the action of the ventral cochlear nucleus?

Answer 6

Horizontal localization of sound

Question 7

Describe the monaural tract.

Answer 7

Cochlear nerve fibers enter cell bodies located in the dorsal cochlear nucleus

Fibers cross to the contralateral side via the dorsal acoustic stria

Ascend in the lateral leminiscus

Synapse at the inferior colliculus - nuclei of the lateral leminiscus

Travel through the brachium of the inferior colliculus to synapse at the medial geniculate nucleus

Will then travel through sublenticular limb of internal capsule to synapse at Layer 4 of the primary auditory cortex

Question 8

Describe the binaural tract.

Answer 8

Cochlear nerve fibers enter cell bodies in the ventral cochlear nucleus

Fibers project bilaterally passing through the trapezoid body to the superior olivary nucleus (medial + lateral)

Fibers from the medial and lateral olivary nucleus ascend along lateral leminiscus to inferior colliculus (nuclei of lateral leminiscus)

Will travel through brachium of inferior colliculus to synapse at medial geniculate nucleus

Fibers then travel through sublenticular limb internal capsule to synapse at layer 4 of primary auditory cortex

Question 9

What is conduction deafness?

Answer 9

Deficit related to obstructed transformation of sound to TM or ossicle chain

Question 10

What is sensorineural deafness?

Answer 10

Results from damage to cochlea, cochlear nerve, and cochlear nuclei

Question 11

What is central deafness?

Answer 11

Damage to central pathways

Question 12

What does the Basilar artery supply in regards to the auditory pathway?

Answer 12

Cochlea

Auditory nuclei of pons and medulla

Question 13

What does the Labyrinthine artery supply in regards to the auditory pathway?

Answer 13

Inner ear

Cochlear nuclei

Question 14

What does the Short circumferential branches of the Basilar artery supply in regards to the auditory pathway?

Answer 14

Superior olivary complex

Lateral Leminiscus

Question 15

What do the Superior cerebellar and Quadrigeminal arteries supply in regards to the auditory pathway?

Answer 15

Inferior colliculus

Question 16

What does the Thalamogeniculate artery supply in regards to the auditory pathway?

Answer 16

Medial geniculate bodies

Question 17

What does the M2 segment of MCA supply in regards to the auditory pathway?

Answer 17

Primary auditory and association cortices

Question 18

What artery supplies the cochlea?

Answer 18

Basilar artery

Question 19

What artery supplies the Lateral leminiscus?

Answer 19

Short circumferential branches of Basilar a.

Question 20

What artery supples the primary auditory and association cortices?

Answer 20

M2 segment of MCA

Question 21

What artery supplies the auditory nuclei of pons and medulla?

Answer 21

Basilar artery

Question 22

What artery supplies the Cochlear nuclei?

Answer 22

Labyrinthine artery

Question 23

What artery supplies the Superior olivary complex?

Answer 23

Short circumferential branches of Basilar a.

Question 24

What artery supplies the inferior colliculus?

Answer 24

Superior cerebellar a.

Quadrigeminal a.

Question 25

What artery supplies the Medial geniculate bodies?

Answer 25

Thalamogeniculate a.

Question 26

What artery supplies the inner ear?

Answer 26

Labyrinthine a.

Question 27

Occlusion of AICA results in what?

Answer 27

Monaural hearing loss Occludes: Emerging fibers of facial nerve Pontine gaze center Also results in ipsilateral facial paralysis and inability to look toward side of lesion

Question 28

In most humans, the left hemisphere is dominant. What are the analogous Wernike's and Broca's area responsible for in the right hemisphere?

Answer 28

Analogous Wernike's = interpreting non-verbal signals (ex: sarcasm) Analogous Broca's = producing non-verbal communication - emotional gestures, intonation of speech

Question 29

Describe how language is produced.

Answer 29

Primary auditory cortex --> auditory discrimination Auditory association cortex --> classification of sounds (language versus other sounds) Wernike's area --> auditory comprehension, vocabulary Subcortical connection --> link Wernike's to Broca's Broca's area --> instructions for language output Oral and throat region of sensorimotor cortex --> cortical output to speech muscles

Question 30

What connects Wernike's to Broca's?

Answer 30

Arcuate fibers

Question 31

What occurs at Broca's area?

Answer 31

Word processing Grammar Word production Articulation

Question 32

What occurs at the lateral temporal cortex?

Answer 32

Semantic knowledge Word recognition (meaning)

Question 33

What occurs at Wernike's area?

Answer 33

Word representation Word retrieval

Question 34

What is arcuate fasciculus responsible for?

Answer 34

Word repetition

Question 35

What occurs at dorsal premotor cortex in regards to language?

Answer 35

Motor programs for articulation

Question 36

What is agnosia?

Answer 36

Inability to identify an object | You can see what it is but you don't know what it is

Question 37

What is auditory agnosia? | Where is the lesion?

Answer 37

Inability to describe a sound You can hear the ambulance but you can't tell me the sound came from the ambulance Lesion = auditory association cortex

Question 38

What is Wernike's aphasia? Fluent or non-fluent?

Answer 38

Receptive or fluent aphasia Defect in the comprehension of language Unable to understand language, read (Alexia), or write (agraphia)

Question 39

What is Broca's aphasia? Fluent or non-fluent?

Answer 39

Expressive or non-fluent aphasia | Loss of ability to speak fluently, can understand

Question 40

What happens with a global lesion? Fluent or non-fluent?

Answer 40

Results in non-fluent aphasia Lesion at the lateral sulcus = Wernike's + Broca's affected

Question 41

What happens with a transcortical lesion? Fluent or non-fluent?

Answer 41

Sensory or motor loss Sensory = fluent, ACA-MCA border zone infarction Motor = nonfluent, MCA-PCA border zone infarction Can repeat

Question 42

What is conduction aphasia? Fluent or non-fluent?

Answer 42

Fluent aphasia Lesion at the supra marginal gyrus and arcuate fasciculus Can't repeat Intact fluency, good comprehension Speech interrupted by word finding difficulties Reading intact, writing impaired

Question 43

What is anomic aphasia?

Answer 43

Word finding deficiency | Can repeat