Auditory Tracts Flashcards
Draw the Monoaural Auditory tract
Ok
What type of information does the monoaural tract transmit?
Sounds from single ear
Draw the binaural tracts
Ok
What type of info do binaural tracts transmit?
Differences between sounds at both ears
Where doe the monoaural and binaural tract synapse at in the cortex?
Layer IV of primary auditory cortex in the anterior transverse temporal gyrus
Is there tonotopical organization in the auditory tracts?
Yes, high and low pitched sounds are organized tonotopically in these tracts
What happens at the olive, lateral lemniscus and inferior colliculus in the auditory tracts?
Further crossing over of some of the fibers, so hitting a side of the tract isn’t gonna cause total deafness because of this “insurance”
What is conduction deafness?
Deafness from obstructed, altered TM or ossicle chain
Ipsilateral ear is affected
What is sensorineural nerve deafness?
Deafness due to damage to cochlea, cochlear part of CN VIII or cochlear nuclei
Ipsilateral ear is affected
What is central deafness?
Damage to the central pathways after the Cochlear nucleus
Does NOT result in deafness due to the crossing over, but can have trouble with sound localization/focus
What does the basilar artery supply?
Cochlea and auditory nuclei of pons and medulla
What does the internal auditory (labyrinthine) artery supply?
From AICA, supplies inner ear and cochlear nuclei
What happens when AICA is occluded?
Monoaural (one ear) hearing loss.
Can also damage the facial nerve and the pontine (horizontal) gaze center, so you can have ipsilateral facial paralysis and inability to look toward side of lesion
What does the short circumferential branches of basilar supply?
Superior olivary complex and lateral lemniscus
What does the superior cerebellar and quadrigeminal arteries supply?
Inferior colliculus
What do the thalamogeniculate arteries supplies?
Medial geniculate bodies
What does M2 segment supply?
Primary auditory and association cortices
Broca’s and Wernicke’s areas
Both in left hemisphere in most adults
Broca: producing language, grammar
Wernicke’s: understanding spoken and written language
Area analogous to Wernicke’s
Area analogous to Broca’s
- allows interpretation of body language
- allows interpretation of gestures and tone of speech
Describe the pathway of neural processing of language
Auditory/visual and association cortices (help, but not necessary) > wernicke’s > subcortical connections > Broca’s > oral and throat region of sensorimotor cortex
What is Broca’s specifically responsible for?
Word processing
Grammar (syntax)
Word production
Articulation
What is the lateral temporal cortex responsible for?
Semantics Word recognition (meaning)
What is wernicke’s specifically responsible for?
Word representation and retrieval. Takes visual word form as input to put the letters together
What is the arcuate fasciculus and dorsal premotor cortex responsible for?
- word repetition
- motor programs for articulation
Auditory agnosia:
Cause
Clinical
Bilateral sensory association cortex lesion
-cannot describe what sound you’re hearing even if you hear it
Wernicke’s aphasia
Cause
Clinical
- temporal gyrus, parietal lobule damage
- cannot understand, read (alexia), write (agraphia) language but can express fluent speech (word salads). Patient unaware of deficits
Broca’s aphasia
Inferior frontal gyrus damage
Severe form: mutism, less sever form = limited speech
Labored, slow speech. Telegraphic speech. Patient aware of deficit
Global aphasia:
Cause
Clinical
Lateral sulcus lesion.
Receptive and expressive deficits, cannot read or write.
Transcortical sensory aphasia:
Cause
Clinical
MCA-PCA watershed lesion
Similar to wernicke’s but patient able to repeat
Transcortical motor aphasia:
Cause
Clinical
ACA-MCA watershed zone lesion
Similar to broca’s but patient has intact grammar and repetition abilities.
Conduction aphasia:
Cause
Clinical
Lesion of supramarginal gyrus and arcuate fasciculus.
Patient cannot repeat, having hard time “finding” words, impaired writing
Mixed transcortical aphasia:
Cannot produce own speech, or comprehend, but can repeat
