auditory tracts Flashcards
primary afferent auditory pathway
CN VIII chochlear part –spiral ganglion–> brainstem at pontomedullary junction –> ascending and descending bundles
ascending –> anterior subdivision of ventral cochlear nucleus
descending –> posterior subdivision of ventral cochlear nucleus and dorsal cochlear nucleus
ascending bundle of auditory tract synapses on which nuclei?
anterior subdivision of ventral cochlear nucleus
descending bundle of auditory tract synapses on which nuclei
posterior subdivision of ventral cochlear nucleus and dorsal cochlear nucleus
dorsal cochlear nucleus
ID sound source elevation and ID complex spectral characteristics of sound
ventral cochlear nucleus
horizontal localization of sound
monaural tracts
- # ears
- routed to which side?
1 ear, contralateral side
monaural tract
-pathway
cell bodies in dorsal cochlear nucleus cross via dorsal acoustic stria (pons) –> ascend lateral lemniscus –> inferior colliculus –> brachium of inferior colliculus –> medial geniculate nucleus –> sublenticular limb of posterior internal capsule –> layer IV of primary auditory cortex (Heschl’s gyrus) in temporal lobe
Where does the monaural tract cross to the contralateral side?
dorsal acoustic stria of the pons
binaural tract
- # of ears
- routed to which side?
2 ears, bilateral
binaural tract
-function
receive, compare, and transmit input
binaural tract
-pathway
cochlear division of CN VIII –> ventral cochlear nuclei in medulla –> bilateral projection through trapezoid body in the pons –> superior olivary complex (nucleus) –> medial superior olivary nucleus and lateral superior olivary nucleus –> lateral lemniscus –> inferior colliculus –> brachium –> medial geniculate nucleus –> sublenticular portion of internal capsule –> layer IV of primary auditory cortex (herschl’s gyrus)
all nerve cells from spiral ganglia will synapse in ___
cochlear nuclei
What do the monaural and binaural paths have in common?
inferior colliculus, brachium, medial geniculate nucleus, primary auditory cortex
conduction deafness
deficit related to an obstructed or altered transformation of sound to the tympanic membrane or through the ossicle chain
-external or middle ear
sensioneural deafness
results from damage to the cochlea, the cochlear part of CN VIII, or to the cochlear nuclei
-ipsilateral
central deafness
damage to the central pathways
-problems with localization of sound
basilar artery
blood supply to cochlea, auditory nuclei of pons and medulla
internal auditory (labyrinthine artery)
- branch of AICA
- inner ear and cochlear nuclei
occlusion of AICA
- monaural hearing loss
- facial nerve palsy
- pontine gaze center
- inability to look toward side of lesion
short circumfrential branches of the basilar A
superior olivary complex and lateral lemniscus
superior cerebellar and quadrigeminal arteries from PCA
inferior colliculus
thalamogeniculate arteries
medial geniculate bodies
M2 segment of MCA
primary auditory and association cortices
dominant hemisphere
LEFT if right handed
may be either if left handed
94% LEFT
Wernicke’s area
comprehension of spoken language
Broca’s area
- instruction for language output
- planning the movements to produce speech
- providing grammatical function of words
non-dominant Wernicke’s area
interpreting nonverbal signals from other people, interpreting sarcasm, understanding pitch and tone
non-dominant Broca’s area
instructions for producing non-verbal communication including emotional gestures and intonation of speech
pathway of language in the brain
primary auditory cortex –> auditory association cortex –> Wernicke’s area –> subcortical connections through arcuate fibers –> Broca’s area –> oral and throat region of sensorimotor cortex
What part of the brain functions for auditory discrimination?
primary auditory cortex
What part of the brain functions for classification of sounds (language vs other sounds)
auditory association cortex
What part of the brain functions for auditory comprehension, vocabulary?
Wernicke’s area
What part of the brain functions to link Wernicke’s and Broca’s areas?
subcortical connections - arcuate fibers
What part of the brain functions for instructions for language output?
Broca’s area
What part of the brain functions for cortical output to speech muscles?
oral and throat region of sensorimotor cortex
function of lateral temporal cortex
semantic knowledge and word recognition (meaning)
function of arcuate fasciculus
word repetition
function of dorsal motor cortex
motor programs for articulation
function of Wernicke’s area
word representation and word retrieval
auditory agnosia
- lesion to unimodal sensory association cortex bilaterally
- inability to describe a sound that has been heard
agnosia
inability to ID an object despite being able to perceive it
Wernicke’s aphasia (receptive or fluent aphasia)
- defect of the comprehension of language
- expression is fine
- unable to understand what is said to them
- alexia
- agraphia
- display fluent paraphasic speech
- on a spectrum
- not aware that they cannot comprehend
alexia
unable to read
agraphia
unable to write comprehensible language
anatomical area of Wernicke’s
- temporal lobe: superficial temporal gyrus
- parietal lobe: angular gyrus and supermarginal gyrus
Broca’s aphasia (expressive aphasia or non-fluent aphasia)
- loss of the ability to speak fluently
- can understand spoken and written language
- most severe: mutism
- less severe: limited speech, short habitual phrases, slow, labored, poor enunciation, telegraphic speech
telegraphic speech
nonessential words are omitted
Can Broca’s aphasia pt understand what is said?
yes - may get frustrated or depressed
Can Wernicke’s aphasia pt understand what is said?
no, but they don’t realize they’re not understanding
Can Broca’s aphasia pt repeat?
no
Can Wernicke’s aphasia pt repeat?
no
global aphsia
- lesion of lateral sulcus
- both Wernicke’s and Broca’s hit
- receptive and expressive deficits
- reading and writing impaired
- won’t acknowledge you
transcortical aphasia
- can repeat
- motor similar to broca’s
- sensory similar to wernicke’s
conduction aphasia
- fluent aphasia
- lesion of supramarginal gyrus and arcuate fasiculus
- can’t repeat
- intact fluency
- good comprehension
- speech interupted by word-finding difficulties
- reading intact, writing impaired
anomic aphasia
word finding difficulties
