Auditory Pathways and Language Flashcards
Auditory pathway overview
Primary afferent CN VIII cochlear part
Cell bodies in spiral ganglion
Enter brainstem at pontomedullary junction
Divide into ascending and descending bundles
Ascending bundles of auditory pathway
Ascending bundle synapses in the anterior subdivision of the ventral cochlear nucleus
Descending bundles of auditory pathway
Descending bundles synapse in the posterior subdivision of the ventral cochlear nucleus and in the dorsal cochlear nucleus
Monaural tracts
Info about sounds at a single ear
Routed to contralateral dorsal cochlear nucleus via dorsal acoustic stria
Ascend in lateral lemniscus to synapse in the inferior colliculus
Axons travel via brachium of the inferior colliculus to the medial geniculate nucleus
Axons then travel through sublenticular limb of internal capsule to layer IV of the primary auditory cortex (Heschl’s gyrus) and synapse
Binaural tracts
Info about differences in sounds at both ears
Routed to ventral cochlear nuclei, project bilaterally to the superior olivary complex (medial and lateral nuclei)
Cell bodies ascend in the lateral lemniscus to the inferior colliculus
Cell bodies in inferior colliculus travel to medial geniculate nucleus
Cell bodies in medial geniculate nucleus pass through sublenticular limb of internal capsule and synapse in Heschl’s gyrus (primary auditory cortex layer IV)
Blood supply to cochlea and auditory nuclei of the pons and medulla
Basilar artery
Blood supply to inner ear and cochlear nuclei- lesion causes what
Labyrinthine artery from AICA
Lesion causes monoaural hearing loss
May also damage facial nerve and pontine gaze center, resulting in monaural deafness combined with ipsilateral facial paralysis and inability to look toward side of lesion
Blood supply to superior olivary complex and lateral lemniscus
Short circumferential basilar branches
Inferior colliculi blood supply
Superior cerebellar and quadrigeminal arteries
Blood supply to medial geniculate bodies
Thalamogeniculate branches
Blood supply to primary auditory and association cortices
M2 segment of middle cerebral artery
Wernickes area
Comprehension of spoken and written language
Brocas area
Instruction for language output
Planning the movements to produce speech
Providing grammatical function of words
Analogous area to wernickes area in the right hemisphere
Interpreting nonverbal signals from other people
Analogous area to brocas area in the right hemisphere
Instructions for producing non-verbal communication including gestures and intonation of speech
Lateral temporal cortex function in language
Semantic knowledge, word recognition (meaning)
Auditory agnosia
Inability to identify an object despite being able to perceive it
Inability to describe a sound that has been heard
Lesion is in unimodal sensory association cortex bilaterally
Wernickes area lesion
Defect of the comprehension of language, expression is fine
Unable to understand what is said to them
Unable to read
Unable to write comprehensible language
Display fluent paraphasic speach
Brocas aphasia
Loss of ability to speak fluently
Can understand spoken and written language
In most severe form- patient is mute
Speech is slow, labored, poor enunciation
Non-essential words are omitted
Global aphasia
Type of non-fluent aphasia
Lesion of lateral sulcus
Receptive and expressive deficits
Reading and writing impaired
Conduction aphasia
Fluent aphasia
Lesion of supramarginal gyrus and arcuate fasciculus
Cant repeat
Intact fluency
Good comprehension
Speech interrupted by word finding difficulties
Reading intact, writing impaired
