1. Auditory Pathways Flashcards
characterisitic of primary affernt CN VIII cochlear part
cell body: in spiral ganglion
enter br.st: at Pontomedullary jxn
synapse: in cochlear nuclei (dorsal & ventral)
steps of monaural tracts
-single ear sound to CONTRALAT side
- cell bodies in dorsal cochelar nucleus - cross contralat via dorsal acoustic stria
- ascend in lateral lemniscus & synapse in inferior colliculus
- 2nd axon travel up via branchium of inferior colliculus
- synapse in medial geniculate nucleus
- 3rd axon synape in layer IV of primary auditory cortex
path of binaural tracts
info about differences btn sound at both ears
- cell bodies in ventral cochlear nucleus up BILATERALLY thru trapezoid body to the superior olivary nucleus (complex) (SON)
- medial and lateral SON up via lateral lemniscus & synapse on inferior colliculus
- 2nd axon travel up via branchium of inferior colliculus
- synapse in medial geniculate nucleus
3rd axon synape in layer IV of primary auditory cortex
what are the 3 types of deafness
conduction
sensorineural
central
how does conduction deafness occur
deficit due to obsturcted/altered transformation of sound to TM or thru ossicle chain
how does sensorineural deafness occur
damage to cochlea, cochlear part of CN 8 or cochlear nuclei
how does central deafness occur
damage of central pathways
what is the blood supply for cochlea & auditory nuclei of pons & medulla
basilar A
which A supplies the inner ear & cochlear nuclei
Internal auditory (labyrinthine) A (branch of AICA)
how does occlusion of AICA affect audition
monaural hearing loss
-also facial N & pontine gaze center cause monaural deafness w ipsilat facial paralysis & inability to look toward side of lesion
what is the blood supply of superior olivary complex & lateral lemniscus
short circumferential branches of basilar
what is the blood supply of the inferior colliculus
superior cerebellar A
quadrigeminal A
what supplies the medial geniculate body
thalamogeniculate As
what is the blood supply of the primary auditory & association cortices
M2 MCA
what side of the brain is language dominante
left hemisphere
Wernicke’s area fxn & lesion
comprehension of spoken language
receptive/fluent aphasia (expression is fine)
- unable to understand, read or write comprehensible language (agraphia)
- fluent paraphasic speech
what is the fxn of Broca’s area & what happens when there is a lesion
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
what is represented in the right hemisphere
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)
what is auditory agnosia
how does it occur
inability to identify/describe sound that is being heard
-lesion = unimodal sensory association cortex bilaterally
What happens if you lesion the lateral sulcus
global (nonfluent) aphasia
receptive & expressive deficits plus reading/writing impairment
what occurs if you lesion the supramarginal gyrus & arcuate fasciculus
conduction aphasia (fluent)
intact fluency, good comprehension, reading intact
cant repeat, difficulty finding words, writing impaired
what occurs if you lesion ACA-MCA border zone
transcortical motor aphasia (non fluent)
like broca’s but grammar is preserved
what occurs if you lesion MCA-PCA border zone
transcortical sensory aphasia (fluent)
preserved grammer & reptition
impaired comprehension & naming
