Neuro Exam V

pinna, auditory canal, tympanic membrane

direct sound pressure changes to the tympanic membrane

3 bones and 2 muscles in an air-filled cavity with a pressure equalizing (eustachian) tube

impedence matching and attenuation reflex

vestibular system and cochlea

transduction, tonotopic organization, balance

stapes movement on the oval window displaces perilymph in scala vestibuli + endolymph in scala media, which deflects basilar membrane and moves hair cells on organ of Corti, which bends stereocilia, which opens mechano-gated K+ channels causing depolarization, which triggers exocytosis and releases glutamate that binds to the neurites of the auditory nerve.

cochlear amplifier, increase amplitude of traveling wave due to embedded motor proteins which cause them to shorten during depolarization

hair cells, spiral ganglion, ipsilateral cochlear nuclei, ipsilateral and contralateral superior olive, inferior colliculus, thalamus, auditory cortex

phase locking

phase locking (volley principle), tonotopy

tonotopy alone

interaural time delay (discrete sound), phase delay (continuous sound)

interaural intensity difference/head shadow effect

amount of basilar membrane deflection, amplitude of traveling wave

both have a macula, with cilia on hair cells projecting into a gelatinous cap with calcium carbonate crystals on top

hair cells cluster in a bulge of the fluid filled tube (ampulla), and cilia project into a gelatinous area (cupula)

gravity/motion pulls on otoliths, deforming gelatinous cap, bending cilia, resulting in depolarization

fluid in semicircular canals moves on a delay relative to walls of the canal, exerting force on the cupula and bending the cilia

vestibular cells, scarpa's ganglion, ipsilateral medial + lateral vestibular nuclei. MVN, medial longitudinal fasciculus, neck and eye muscles. LVN, vestibulospinal tract, cerebellum, limb motor neurons