Lecture 09 Auditory System

Question 1

What is the primary neuron in the auditory system?

Answer 1

Cochlear n

Question 2

Where is the primary neuron located?

Answer 2

in the spiral ganglion which is embedded in the modiolus

Question 3

Where do the central processes of the cochlear n terminate?

Answer 3

in the dorsal and ventral cochlear nuclei

Question 4

Describe the dorsal and intermediate acoustic striae

Answer 4

The dorsal (stria medullaris acoustica) and intermediate striae decussate in the upper medulla
ascend in the contralateral Lateral Lemniscus

Question 5

Where does the LL terminate ?

Answer 5

inferior colliculus

Question 6

What is the path of the ventral acoustic stria?

Answer 6

cross the medial lemniscus, form the trapezoid body

Fibers terminate bilaterally in the superior olivary nucleus

Question 7

Where does SON (superior olivary nucleus) project its fibers to?

Answer 7

inferior colliculus primarily through the ipsilateral lateral lemniscus

Question 8

What directly links the auditory association area to Broca’s speech area in the frontal lobe?

Answer 8

longitudinal fasiculus

also called arcuate fasciculus

Question 9

Describe the SON complex

Answer 9

collections of nuclei dispersed along the ascending auditory pathway
Play a role in modifying auditory information
Fibers pass through the vestibular division and cross over to the cochlear division via vestibulocochlear anastomsis

Question 10

What is the medial superior olivary nucleus important in?

Answer 10

localizing sounds

Question 11

What do neurons is the lateral superior olivary nucleus give rise to?

Answer 11

most of the olivocochlear efferents, which exert inhibitory influences upon the organ of Corti

Question 12

Unilateral lesions of the cochlear n results in what?

Answer 12

ipsilateral complete deafness

Question 13

What does unilateral lesion of the central auditory pathway result in?

Answer 13

bilateral diminution of hearing which is more prominent in the contralateral ear

LL, inferior colliculus and branchium and medial geniculate body

Question 14

What do lesions of the primary auditory cortex result in?

Answer 14

a difficulty in localizing sounds and tone discrimination

It does NO result in hearing deficits

Question 15

What is conduction aphasia ?

Answer 15

fluent language
severe impairment of repetition, difficutly in reading aloud, severe anomia, normal auditory comprehension

Right hemiparesis and hemianopia
orofacial and bilateral limb apraxia may be present

Question 16

What is conduction aphasia caused by?

Answer 16

lesion of arcuate fasiculus

Question 17

What is auditory agnosia

Answer 17

inability to comprehend auditory information

spoken and written language as well as other sensory modalities may remain intact

Question 18

What is auditory agnosia caused by?

Answer 18

lesions in auditory association (POT) cortex

Question 19

What is fluent paragrammatical aphasia

Answer 19

inability to comprehend the spoken or written word
speak quiet fluently but speech patterns demonstrate numerous word substitutions, neologisms (new word creations) and circumlocution of language

Called wernicke’s aphasia or receptive aphasia

Question 20

What causes fluent paragrammatical aphasia?

Answer 20

damage to wernicke’s area in the dominant hemisphere

Question 21

What is the main function of Wernicke’s area?

Answer 21

comprehension