SPLH 620 Unit 2 Study Guide with Complete Solutions(RATED A+)
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Course
SPLH 620
Institution
SPLH 620
CN VIII: Vestibulocochlear - ANSWER-hearing and balance
- vestibular division
- cochlear division
- hearing and balance are functionally very different senses but begin similarly peripherally
-vestibular: position and movement of head
anatomy of hearing and balance - ANSWER-• Outer ear...
SPLH 620 Unit 2 Study Guide 2023-2024 with Complete Solutions(RATED A+)
CN VIII: Vestibulocochlear - ANSWER-hearing and balance - vestibular division - cochlear division - hearing and balance are functionally very different senses but begin similarly peripherally -vestibular: position and movement of head
anatomy of hearing and balance - ANSWER-• Outer ear - Pinna - Ear canal • Middle ear - Tympanic membrane - Ossicles (malleus, incus, stapes) • Inner ear - Cochlea - Vestibular system
middle ear - ANSWER-- Tympanic membrane - Air filled - Ossicles (Malleus, incus, stapes) - Oval Window
inner ear (cochlea) - ANSWER-fluid filled
middle ear function - ANSWER-•Amplification of signal •Transforms signal
•(acoustic->mechanical)
inner ear function - ANSWER-•Transforms signal: •Mechanical -> chemoelectric •Represent sound frequencies
How is sound transmitted? - ANSWER-Vibrations transmitted through the tympanic membrane, middle ear ossicles, and oval window reach the perilymph (fluid) of the inner
ear
cochlea - ANSWER-- a coiled tube (2.5 turns) with three chambers: • Scala vestibuli (perilymph)
• Scala tympani (perilymph) • Scala media (endolymph)
organ of corti - ANSWER-a stirp of hair cells that rest on the basilar membrane, that are within the cochlear membrane - wave energy from the cochlea causes the basilar membrane to vibrate, bending hair cells, generating action potentials
ear hair cells - ANSWER-- inner hair cells
- outer hair cells
- 90-95% of all cochlear nerve fiber receives input from IHC
-OHC amplify signal
tonotopic organization - ANSWER-an arrangement in which neurons that respond to different frequencies are organized anatomically in order of frequency
- high frequency sounds at the BASE
- low frequency sounds at the APEX
auditory pathway - ANSWER-1. Sound enters ear and stimulates the Auditory Nerve (CN VIII) 2. Information is passed through the Superior Olive, Lateral Lemniscus, Inferior Colliculus and Thalamus(medialgeniculatenucleusofthethalamus) (MGN) • Spatial hearing computed by interaural level / time differences 3. Auditory Cortex receives Thalamic input and processes signal - Tonotopic map is preserved in cortex
auditory pathway components - ANSWER-• Hair cells --> dorsal and ventral cochlear nuclei • Dorsal cochlear nucleus --> most axons cross over to inferior colliculus • Ventral nucleus --> axons synapse on the ipsilateral and contralateral superior olivary nucleus
auditory pathway components continued - ANSWER-• Lateral lemniscus - a large fiber bundle of the ipsilateral and contralateral ventral and dorsal axons • synapses in the inferior colliculus and goes on to the medial geniculate nucleus of the thalamus • From there to the temporal lobe of the auditory cortex • Each hemisphere receives info from both ears
Anatomy of Auditory Pathways - ANSWER--Afferents from spiral ganglion cells enter brainstem in the auditory vestibular nerve via 8th nerve at medulla
-Innervate both ipsilateral dorsal and ventral cochlear nuclei
-Cells in the ventral cochlear nucleus send out axons that project to the superior olive (superior olivary nucleus) on both sides of the brainstem
-Axons of the olivary neurons ascend via lateral lemniscus and innervate the inferior colliculus (IC) in the midbrain
-Inferior colliculus sends axons to the MGN
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