auditory tracts Flashcards
what is the primary afferent of the auditory pathway
cochlear part of CN VIII
where are the cell bodies of the cochlear part of CN VIII
spiral ganglion
where does the primary afferent of the auditory pathway enter the brainstem
pontomedullary junction
where does the ascending bundle of the cochlear part of CN VIII synapse
anterior subdivision of ventral cochlear nucleus
where does the descending bundle of the cochlear part of CN VIII synapse
- dorsal cochlear nucleus OR
- posterior subdivion of ventral cochlear nucleus
what is the function of the dorsal cochlear nucleus
identifying source of a sound and complex characteristics of sound
what is the function of the ventral cochlear nucleus
horizontal localization of sound
what is the route of monaural information from the dorsal cochlear nucleus
dorsal cochlear nucleus => dorsal acoustic stria => contralateral lateral leminiscus => *inferior colliculus
what is the route of monaural information from the inferior colliculus
brachium of inferior colliculus => synpase in MGN => Primary auditory cortex
where does monaural information from the MGN synapse
layer IV of the primary auditory cortex
what is binaural information
information about differences between sounds in both ears
what is the route of binaural information from the ventral cochlear nuclei
projects bilaterally through trapezoid body to superior olivary complex
what is the route of binaural information from the superior olivary complex
medial and lateral olivary nuclei => lateral lemniscus => *inferior colliculus
what is the overall route of monaural information
dorsal cochlear nucleus => dorsal acoustic stria => contralateral lateral lemniscus => *inferior colliculus => *MGN => *layer IV of primary auditory cortex
what is the route of binaural information from the inferior colliculus to the primary auditory cortex
*inferior colliculus => *MGN => * layer IV of primary auditory cortex
what is the overall route of binaural information
ventral cochlear nucleus => bilateral superior olivary nuclei => lateral lemniscus => *inf colliculus => *MGN => * layer IV of primary auditory cortex
what is the cause of sensorineural hearing loss
damage to CN VIII (cochlear part), cochlea or cochlear nuclei
what is the cause of conductive hearing loss
obstructed pathway of sound to tympanic membrane or through ossicles
what is the blood supply to the cochlea and auditory nuclei of the pons and medulla
basilar artery
what supplies the cochlear nuclei and inner ear
labryrinthine a. (branch of AICA)
what deficits will be seen in occlusion of aica
monaural hearing loss
possibly also ipsilateral facial paralysis and inability to look towards side of lesion
what supplies the superior olivary complex and lateral lemniscus
short circumferential branches of basilar a
what supplies the inferior colliculus
superior cerebellar a AND
quadrigeminal as
what supplies the primary auditory and association cortices
M2 segment of MCA
what supplies the medial geniculate body
thalamogeniculate arteries
what is the function of wernicke’s area in the dominant hemisphere
comprehension of spoken language
what is the function of wernicke’s area in the non-dominant hemisphere
interpretation of nonverbal signals
what is the function of broca’s area in the dominant hemisphere
grammar, language and speech production
what is the function of broca’s area in the non-dominant hemisphere
instruction for producing non-verbal communication (tone, gestures)
what is auditory agnosia
inability to describe a sound that has been heard
what lesion causes auditory agnosia
bilateral temporal lesion
fluent aphasia results from damage to what area
wernickes
what sxs are associated w/ lesion to wernicke’s area
fluent aphasia
inability to read/write (alexia/agraphia)
unable to understand others
can pt’s with a broca’s area lesion understand spoken or written commends
YES
how does a broca’s area lesion present
mutism if severe
non-fluent aphasia (slow, labored speech)
a lesion to what structure causes global aphasia
lateral sulcus
a lesion to what structure causes conduction aphasia
arcuate fasciculus
what are the sxs of conduction aphasia
pt can’t repeat but can comprehend
reading intact, writing impaired
speech is fluent, interrupted by word-finding difficult
what features are common between the binaural and monaural tracts
- synapse in cochlear nuclei, inferior colliculus, MGN, primary auditory cortex
- fibers cross multiple times in brainstem
the ability to repeat differentiates wernicke’s aphasia from what?
transcortical SENSORY aphasia
the ability to repeat differentiates broca’s from what?
transcortical MOTOR aphasia
what is receptive aphasia
fluent aphasia
what is expressive aphasia
non-fluent
infarction of the MCA-PCA border zone results in what condition
transcortical sensory aphasia
infarction of ACA-MCA border zone results in what condition
transcortical motor aphasia
occlusion of what artery causes global aphasia
MCA
what structure is responsible for word repetition
arcuate fasciculus
what tract does broca’s area relay information to to product speech
corticobulbar
what structure is responsible for word recognition
lateral temporal cortex
where are arcuate fibers
within the temporal lobe, extending from wernicke’s to broca’s area
what area is responsible for reading
wernickes
what area is responsible for understanding sarcasm
area analogous to wernicke’s
what area is responsible for producing inflection
area analogous to broca’s
from what artery do the quadrigeminal arteries branch
PCA
what causes central deafness
damage to monaural or binaural pathway
what are the sxs of central deafness
can hear but can’t localize sound
why don’t lesions of the monaural or binaural pathways cause deafness
because the fibers cross multiple times in the brainstem
