Auditory tracts Flashcards
How is the auditory information divided as it enters the brainstem via CN VIII
Auditory information coming from the spiral ganglion will enter the brainstem via the pontomedullary junction and divide into ascending and descending bundles as it synapses on the cochlear nuclei
where does the ascending bundles synapse in the cochlear nuclei
ascending information synapses in the anterior subdivision of the ventral cochlear nucleus
Where does the descending bundles synapse in the cochlear nuclei
descending bundle synapses in the posterior subdivision of the ventral cochlear nucleus and in the Dorsal cochlear nucleus
Monaural Tract pathway and what information is carried
Monaural information is information about sounds at a single ear and is then routed to the contralateral side of the brain
- Cell bodies in the dorsal cochlear nucleus cross to the contralateral side via the dorsal acoustic stria
- Ascend in the lateral lemiscus to synapse in the inferior colliculus
- cell bodies in the inferior colliculus then have their axons travel through the brachium of the inferior colliculus to the medial genticulate nucleus
- Cell bodies from the medial geniculate nucleus will send their axons through the sublenticular limb of the internal capsule to layer IV of the primary auditory cortex
Binaural Tract pathway and what information is carried
Binaural information carries differences between sounds at both ears and is handled by central pathways that recieve, compare, and transmit this input
- Cell bodies in the ventral cochlear nucleus project bilaterally passing through the trapezoid body to the superior olivary complex (nucleus)
- the axons from the cell bodies in the medial and lateral superior olivary nucleus ascend in the lateral lemniscus to the inferior colliculus
- cell bodies in the inferior colliculus then send their axons through the brachium of the inferior collicuus to the medial genticulate nucleus and synapse their
- The cell bodies in the medial geniculate nucleus will then send their axons through the sublenticular limb of the internal capsule to layer IV of the primary auditory cortex
What is significant about all the crossing over of auditory information in the central pathways
If their is damage in the central pathways normally their is no deafness because information crosses over from each ear
What are the 3 types of deafness
Conduction: deficit related to an obsftructed or altered transformation of sound to the tympanic membrane (ipsilateral deafness)
Sensorineural: results from damage to the cochlea, the cochlear part of the CN VIII or to the cochlear nuclei (ipsilateral deafness)
Central: damage to the central pathways
- results in no deafness
- difficulty localizing where the sound is coming from
- difficulty picking out sound in a noisy area
- dont notice certain sound stimuli
Where does the majority of the blood supply to the cochlea and the auditory nuclei come from
Branches of the basilar artery
WHat does the Internal auditory artery supply and what happens if their is an occlusion in the AICA
also called the labyrinthine artery which is a branch of AICA
supplies the inner ear and the cochlear nuclei
occulusion of the AICA will result in monaural hearing loss and may lead to damaging the facial nerve or the pontine gaze center, giving facial paralysis and inabillity to look toward the side of the lesion
What does the short circumferential branches of the basilar supply
superior olivary nucleus and lateral lemniscus
What does the superior cerebellar and the quadrigeminal artery supply
supplies the inferior colliculus
What does the thalamogeniculare aretery supply
supplies the medial geniculate bodies
What does the M2 segment of the middle cerebral artery supply
supplies the primary auditory and association cortices
Which hemisphere is the dominant hemisphere
the side that processes language 94 percent of people are left hemisphere dominant
What does Wernickes area do
comprehension of spoken and written language
What does Brocas area do
Instruction for language output
planning the movements to produce speech (word production and grammer)
Providing grammatical function of words
What does the right hemisphere do in areas analgous to brocas and wernickes
Area analagous to Wernickes: Interpreting nonverbal signals from other people (body language)
Area analagous to Brocas: Instructions for producing non-verbal communication including emotional gestures and intonation of speech
-adding extra emotional meaning to how we say words
What is the order of language information travel in the brain
Primary auditory cortex (auditory discrimination)
Auditory association cortex (classification of sounds, language vs other sounds)
Wernickes area (auditory comprehension, vocabulary)
Subcortical connections (link wernickes and brocas area)
Brocas area (instructions for language output)
Oral and throat region of sensorimotor cortex (cortical output to speech muscles)
What is the lateral temporal cortex important for
Semantic knowledge: meaning of a sentence word recognition (meaning)
What are the arcuate fasciculations important for
word repetition
What happens if their is damage to the sensory association cortex or the lateral temporal cortex
Auditory agnosia
inabillity to describe a sound that has been heard
must affect it bilaterally
Wernickes area lesion
Wernickes aphasia (receptive or fluent aphasia)
defect of the comprehension of language
unable to understand what is said to them
alexia: unable to read
agraphia: unabe to write comprehensible language
display fluent paraphasic speech
arent aware of there issue
Brocas area lesion
Brocas aphasia or expressive aphasia or non-fluent aphasia
loss of the abillity to speak fluently
can understand spoken and written language
most severe form makes an individual mute
less severe: short habitual phrases
speech is slow, labored, poor enunciation
nonessential words are omitted
Global Lesion
type of non fluent aphasia
lesion of lateral sulcus (both wernickes and brocas are hit)
receptive and expressive defects
reading and writing impaired
Fluency, Grammar, Comprehension, Naming, Repetition, lesion: Broca
Fluency: Non fluent
Grammar: Impaired
Comprehension: IMpaired for complex sentences
Naming: Preserved
Repetition: Impaired for complex sentences
Lesion: Left inferior frontal gyrus (Broca area and surroundings)
Fluency, Grammar, Comprehension, Naming, Repetition, lesion: Wernicke
Fluency: Fluent Grammar: may be normal Comprehension: Impaired for single words Naming: IMpaired Repition: IMpaired for single words Lesion: Left superior temporal gyrus, inferior parietal lobe, posterior middle temporal gyrus, middle temporal gyrus
Fluency, Grammar, Comprehension, Naming, Repetition, lesion: Conduction
FLuency: FLuent Grammar: PReserved Comprehension: normal Naming: preserved Repetition: impaired Lesion: arcuate fasciculations
Fluency, Grammar, Comprehension, Naming, Repetition, lesion: Transcortical motor
Fluency: Nonfluent Grammar: preserved Comprehension: normal Naming: preserved Repetition: preserved Lesion: ACA-MCA border zone infarction
Fluency, Grammar, Comprehension, Naming, Repetition, lesion: Transcortical sensory
Fluency: Fluent Grammar: Preserved Comprehension: impaired Naming: impaired Repetition: preserved Lesion: MCA-PCA border zone
