1. Auditory Pathways

Question 1

characterisitic of primary affernt CN VIII cochlear part

Answer 1

cell body: in spiral ganglion

enter br.st: at Pontomedullary jxn

synapse: in cochlear nuclei (dorsal & ventral)

Question 2

steps of monaural tracts

Answer 2

-single ear sound to CONTRALAT side

1. cell bodies in dorsal cochelar nucleus - cross contralat via dorsal acoustic stria
2. ascend in lateral lemniscus & synapse in inferior colliculus
3. 2nd axon travel up via branchium of inferior colliculus
4. synapse in medial geniculate nucleus
5. 3rd axon synape in layer IV of primary auditory cortex

Question 3

path of binaural tracts

Answer 3

info about differences btn sound at both ears

1. cell bodies in ventral cochlear nucleus up BILATERALLY thru trapezoid body to the superior olivary nucleus (complex) (SON)
2. medial and lateral SON up via lateral lemniscus & synapse on inferior colliculus
3. 2nd axon travel up via branchium of inferior colliculus
4. synapse in medial geniculate nucleus

3rd axon synape in layer IV of primary auditory cortex

Question 4

what are the 3 types of deafness

Answer 4

conduction

sensorineural

central

Question 5

how does conduction deafness occur

Answer 5

deficit due to obsturcted/altered transformation of sound to TM or thru ossicle chain

Question 6

how does sensorineural deafness occur

Answer 6

damage to cochlea, cochlear part of CN 8 or cochlear nuclei

Question 7

how does central deafness occur

Answer 7

damage of central pathways

Question 8

what is the blood supply for cochlea & auditory nuclei of pons & medulla

Answer 8

basilar A

Question 9

which A supplies the inner ear & cochlear nuclei

Answer 9

Internal auditory (labyrinthine) A (branch of AICA)

Question 10

how does occlusion of AICA affect audition

Answer 10

monaural hearing loss

-also facial N & pontine gaze center cause monaural deafness w ipsilat facial paralysis & inability to look toward side of lesion

Question 11

what is the blood supply of superior olivary complex & lateral lemniscus

Answer 11

short circumferential branches of basilar

Question 12

what is the blood supply of the inferior colliculus

Answer 12

superior cerebellar A

quadrigeminal A

Question 13

what supplies the medial geniculate body

Answer 13

thalamogeniculate As

Question 14

what is the blood supply of the primary auditory & association cortices

Answer 14

M2 MCA

Question 15

what side of the brain is language dominante

Answer 15

left hemisphere

Question 16

Wernicke’s area fxn & lesion

Answer 16

comprehension of spoken language

receptive/fluent aphasia (expression is fine)

• unable to understand, read or write comprehensible language (agraphia)
• fluent paraphasic speech

Question 17

what is the fxn of Broca’s area & what happens when there is a lesion

Answer 17

instruction for language output, planning movement of speech & providing grammatical fxn of words

lesion- expressive/non-fluent aphasia –> loss of ability to speak fluently

able to understand spoken & written language

-severe - mutism & less severe - limited speech

Question 18

what is represented in the right hemisphere

Answer 18

area analgous to wernicke’s area: interpret non-verbal signals

area analgous to broca’s area: instruction for making non-verbal communication (emotional gestures & intonation)

Question 19

what is auditory agnosia

how does it occur

Answer 19

inability to identify/describe sound that is being heard

-lesion = unimodal sensory association cortex bilaterally

Question 20

What happens if you lesion the lateral sulcus

Answer 20

global (nonfluent) aphasia

receptive & expressive deficits plus reading/writing impairment

Question 21

what occurs if you lesion the supramarginal gyrus & arcuate fasciculus

Answer 21

conduction aphasia (fluent)

intact fluency, good comprehension, reading intact

cant repeat, difficulty finding words, writing impaired

Question 22

what occurs if you lesion ACA-MCA border zone

Answer 22

transcortical motor aphasia (non fluent)

like broca’s but grammar is preserved

Question 23

what occurs if you lesion MCA-PCA border zone

Answer 23

transcortical sensory aphasia (fluent)

preserved grammer & reptition

impaired comprehension & naming