Auditory Pathways And Language Flashcards
What is the first order neuron in the auditory pathways?
Primary afferent CN 8 Cochlear Part
Why do we not define second and third order neurons for Auditory Pathways?
Bc they cross over so much
What happens if there is a lesion to the auditory pathways?
Deafness does NOT occur
Bc so much crossing over
Where are the cell bodies of the primary afferent cranial VIII cochlear part?
Where do they enter the brainstem?
What do they do after that?
Spiral ganglion
Pontomedullary junction
Divide into ascending and descending bundles
Where do the ascending bundles of the primary afferent CN8 nerve synpase?
In cochlear nuclei
Anterior —> ant. Subdivision of VENTRAL cochlear nucleus
Where do the descending bundles of the primary afferent CN8 nerve synpase?
In cochlear nuclei
Desc. —>
posterior subdivision of VENTRAL cochlear nucleus
& in
DORSAL cochlear nucleus
Where is monoaural info routed to?
Contralateral side
What is conveyed thru Monoaural info?
Info about sounds at a SINGLE ear
What is the monoaural tract?
Dorsal cochlear nucleus (cell bodies here)
—-> cross via dorsal acoustic stria
—> Contra. LL
—> Inferior colliculus (where nuclei of LL is)
—> brachium of inferior collilicus
—> Medial Geniculate nucleus
—> Sublenticular limb of internal capsule
—> layer 4 of Primary auditory cortex
What are 2 other names for the primary auditory cortex?
Heschl’s gyrus
Anterior transverse temporal gyrus
What info does the binaural tracts convey?
Info about different sounds at BOTH ears
Differences allow localization and comparison of sounds
What is the pathway for binaural tracts?
Binaural info —> central pathways (receive compare and transmit this input)
What is the pathway for Binaural tracts?
Ventral cochlear nuclei —> trapezoid body —> superior olivary nuclei (medial and lateral) —> Ascend BILATERALLY in LL —> Inferior colliculus —> Brachium of IC —> MGN —> layer 4 of primary auditory cortex
Broadly, what is the blood supply to the cochlea and auditory nuclei of pons and medulla?
Basilar a.
What is the internal auditory artery a branch of?
What is the other name for it?
AICA
Labyrinthine A.
What does the internal auditory a. Supply?
Inner ear
Cochlear nuclei
What results from an occlusion of AICA?
Monaural hearing loss ipsilaterally
What happens if there is a lesion to the internal auditory A.?
Fibers of facial nerve could be damaged
Fibers of pontine gaze center (horiz.) could also be damaged
Monaural hearing loss ipsilaterally
Facial paralysis ipsilaterally
Unable to look TOWARD side of lesion
What supplies the superior olivary complex and LL?
Short circumferential branches of the Basilar A.
What supplies the inferior colliculus?
Superior cerebellar A.
Quadrigeminal arteries
What supplies the medial geniculate bodies?
Thalamogeniculate arteries
What supplies the primary auditory and association cortices?
M2 segment of the MCA
What causes conduction deafness?
Result?
Obstructed or altered transformation of sound to tympanic membrane or thru ossicle chain
Deficit in hearing
What causes sensorineural deafness?
Results in?
Damage to cochlea (hair cells etc), cochlear part of CN 8 or to cochlear nuclei
IPSILATERAL deafness
What causes central “deafness” ?
Results in?
Damage to central pathways (supeiror olivary nucleus and up)
Trouble localizing sounds
Unable to focus on sound stimuli
(WILL NOT BE DEAF)
What constitutes the Central pathway?
Superior olivary nucleus and up
What is agnosia?
Inability to identify an object despite being able to perceive it
What is auditory agnosia?
Example?
Inability to describe a sound that has been heard
Fire alarm sounds, but unable to identify it as that
What cause auditory agnosia?
Lesion to
Unimodal sensory association cortex BILATERALLY
What is the dominant hemisphere for language?
Left (in 94-95% of adults)
What is wernicke’s area for?
COMPREHENSION of Spoken and written language
Word representation
Word retrieval
What is Broca’s Area responsible for?
Language output, production of speech, GRAMMAR, word processing, articulation
What is the area analogous to wernicke’s area responsible for?
Interpreting nonverbal signals from other people
I.e. body language
What is the area analogous to Broca’s area responsible for?
For producing non-verbal communication like
Emotional gestures
Intonation of speech
If the Areas Analogous to Wernicke’s and Broca’s are damaged, what is the result?
People will take things literally
Will not pick up on body language nuances, gestures, sarcasm
“Won’t get the joke”
What is the pathway for language?
Which 2 steps do you not need to language but for reading?
- Primary auditory cortex
- Auditory association cortex
- Wernicke’s
- Subcortical connections (arcuate fasciculations)
- Broca’s
- Sensorimotor cortex
Do not need steps 1 or 2 (language does not depend on vision or auditory input)
What is the role of the primary auditory cortex?
Auditory discrimination
What is the role of the auditory association cortex?
Classify sounds
Language vs other sounds
What is the role of the Subcortical Connections?
Arcuate fasciculations link wernicke’s and Broca’s area
Allow for WORD REPETITION
What is the role of the sensorimotor cortex (dorsal pre-motor cortex) in language?
Cortical output to speech muscles
What is the role of the the Lateral Temporal Cortex in Language?
Semantic knowledge (if sentence makes sense)
Word recognition (meaning)
What is the visual cortex for in language pathway?
Visual word form
Allows you to see how letters come together to form different words
What are other names for broca’s aphasia?
Expressive aphasia
Non-fluent aphasia
How does Broca’s Aphasia present?
Can’t speak fluently Can understand written and spoken language Should habitual phrases used Slow, labored speech Non-essential words are omitted
If severe enough = can’t speak, Mutism
What lesion could cause Broca’s aphasia?
Lesion to left inferior frontal gyrus
What else is Wernicke’s aphasia known as?
Receptive or fluent aphasia
How does Wernicke’s aphasia present?
Cannot understand language
Expression if fine
Cannot read
Cannot write comprehensibly
Has fluent, paraphasic speech
CANNOT REPEAT
What is alexia?
Inability to write
What is agraphia?
Inability to write comprehensible language
What is fluent paraphasic speech?
Fluent speech but with made up words
What lesion could result in Wernicke’s aphasia?
Lesion to
Left superior temporal gyrus (Broca’s= inf.)
Inferior parietal lobule
Posterior middle temporal gyrus
What is global aphasia?
Presents w/?
Caused by?
Type of non fluent aphasia
Receptive and expressive deficits
Impaired reading and writing
Lesion of lateral sulcus due to massive stroke
What is conduction aphasia?
Presents with?
Due to lesion of?
Type of fluent aphasia
CANT REPEAT (like wernicke’s) but but but
CAN COMPREHEND (unlike wernicke’s)
Fluent
Reading intact
Writing impaired
Speech interrupted by word finding difficulties
Lesion of supramarginal gyrus and ARCUATE FASCICULUS
How does transcortical sensory aphasia present?
~similar to Wernicke’s~
Fluent
Impaired comprehension
Impaired naming
CAN REPEAT
What causes trans cortical sensory aphasia?
MCA - PCA border zone infarction
How does Transcortical Motor Aphasia present?
~similar to broca’s~
Nonfluent
Normal comprehension
Normal naming
GRAMMAR IS OKAY THO
What causes a transcortical motor aphasia?
ACA- MCA border zone infarction
What is mixed transcortical aphasia?
Not fluent (Broca/motor)
Unable to comprehend (wernicke’s/sensory)
Able to repeat (Sensory)
