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Neuroscience I Test 3 > Auditory System > Flashcards

Flashcards in Auditory System Deck (14)
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primary neuron in the auditory pathway

-located in the spiral ganglion in the modiolus
-cochlear division of VIII N is formed by the central processes of bipolar neurons
-central processes terminate in the dorsal (acoustic tubercle) and ventral cochlear nuclei--in the upper medulla


dorsal and intermediate acoustic striae

-visible as the stria medullaris acoustic
-both decussate in the upper medulla and ascend in the lateral lemniscus
-LL terminates upon neurons in the inferior colliculus


ventral acoustic stria

-cross the medial lemniscus and form the trapezoid body
-fibers terminate bilaterally in the superior olivary nucleus (SON)
-SON projects fibers to the inferior colliculus primarily thru the ipsilateral lateral lemniscus


inferior colliculus and medial geniculate body

inferior colliculus-->brachium of inferior colliculus-->medial geniculate body-->sustentacular auditory radiations-->primary auditory cortex


primary auditory cortex

-located in the transverse and superior temporal gyri
-has a general tonotropic organization according to high freq in the caudal aspect and low freq in the rostral aspect


auditory assoc cortex

-for processing and integration of sounds
-located in the parieto-occipito-temporal assoc cortex and Wernicke's area
-superior longitudinal fasciculus links the auditory assoc area to Broca's speech area in the frontal lobe


superior olivary nuclear complex

-represents a collection of nuclei dispersed along the ascending auditory pathway
-play a role in modifying auditory info
-medial superior olivary nucleus--needed for localizing sounds
-neurons in the lateral superior olivary nucleus--gives rise to olivocochlear efferents which exert inhibitory influences upon the organ of Corti
-peripherally the fibers cross over to the cochlear division via the vestibulocochlear anastomosis


pathway for auditory information

primary neuron in spiral ganglion-->central processes of bipolar neurons form the cochlear N of VIII-->
1. dorsal (acoustic tubercle) acoustic stria-->decussate in upper medulla-->ascend in contralateral lateral lemniscus-->inferior colliculus
2. ventral acoustic stria-->cross the medial lemniscus and form the trapezoid body-->terminate bilaterally in superior olivary nucleus-->lateral lemniscus-->inferior colliculus
-->brachium of inf colliculus-->medial geniculate body-->sustenticular auditory radiations-->primary auditory cortex


unilateral lesion of the cochlear N

results in ipsilateral complete deafness


unilateral lesion of the central auditory pathway

-results in bilateral diminution of hearing which is more prominent in the contralateral ear
-involves structures like the lateral lemniscus, inf colliculus, brachium of inf colliculus, and medial geniculate body


lesions of primary auditory cortex

result in difficulty localizing sounds and tone discrimination
-no hearing deficits


conduction aphasia

-lesion of the arcuate fasciculus
-results in conduction aphasia
-fluent language disorder
-characterized by severe impairment of repetition, difficulty reading aloud, marked paraphasia, severe anomia, and normal auditory comprehension
-right hemiparesis and hemianopsia, orofacial and bilateral limb apraxia may be presetn


auditory agnosia

-lesion in the auditory association (POT) cortex
-characterized by inability to comprehend auditory info
-spoken and written language and other sensory modalities in tact


fluent paragrammatical aphasia

-Wernicke's Aphasia
-due to damage to Wernicke's area of dominant hemisphere
-phasic zone appears to be an assembly area for the critical components of language
-characterized by pt's inability to comprehend the spoken or written word
-pt's speak fluently and their speech patterns have word substitutions, new word creations, and circumlocution of language
-also a receptive aphasia