Auditory Pathways Flashcards
Where do the primary afferents of CN8 (cochlear part) enter the brainstem?
Pontomedullary Junction
Where do the afferents of the Cochlear nerve synapse? How?
Dorsal and Ventral Cochlear Nuclei. Splits into Ascending and Descending. Ascending goes to Anterior
What is the function of the Dorsal (or Posterior) Cochlear Nuclei?
Identify sound source elevation and identifying complex characteristics of sound.
What is the function of the Ventral (Anterior) Cochlear Nuclei?
Horizontal location of sound.
Describe the path of Monoaural information.
Cell bodies go to contralateral side via dorsal acoustic stria and synapse in inferior colliculus. From there, axons go to medial geniculate nucleus, to Layer 6 in primary auditory cortex.
Describe the path of Binaural information.
Ventral cochlear nuclei to Superior olivary complex(bilaterally), to inferior colliculus, to medial geniculate nucleus to the Primary Auditory Cortex.
What are ways that deafness can occur?
Damage to conducting structures (tympanic membrane to malleus, incus, stapes), Damage to cochlear part of CN 8 or nuclei, or damage to central pathways
What artery supplies the inner ear? What is it a branch off of?
Labyrinthine Artery, Off of the AICA
What artery supplies the superior olivary complex and lateral lemniscus?
Short circumferential branches of basilar
What artery supplies the inferior colliculus?
Superior Cerebellar and Quadrigeminal.
What artery supplies the medial geniculate bodies?
Thalamogeniculate Arteries
What artery supplies the Primary Auditory Cortex?
M2 of MCA
Which hemisphere is typically dominant for language?
Left Hemisphere.
What is Wernicke’s Area responsible for on the left and right hemispheres, respectfully
Left- Comprehension of spoken language
Right- Interpreting non-verbal signals
What is Broca’s Area responsible for on the left and right hemispheres, respectfully.
Left- Instruction and planning to produce speech.
Right- Producing non-verbal communication and intonation
Describe the flow of synapses to produce language
Primary auditory cortex to Auditory association cortex to Wernicke’s Area to connection to Broca’s and Broca’s to cortical output and speech muscles
What is auditory agnosia? How is it caused?
Inability to describe a sound that has been heard. Lesion in sensory association cortex
How does a patient with a Wernicke’s Area Lesions present?
Can’t understand what is told to them, also can’t read or write comprehensible language. Can talk in paragraph but may not make sense.
How does a patient with a Broca’s Area Lesion spresent?
Can Understand spoken and written language but are unable to speak fluently, have broken words, small words. Will mainly consist of responses of nouns and verbs (telegraphic)
How does a Transcortical motor Lesion present?
Non fluent speech but grammar and everything else is normal
How does a Transcortical sensory Lesion present?
Cannot name items well.
How does a conduction aphasia present?
Can’t repeat and writing is impaired
