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20 Cards in this Set
- Front
- Back
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What receives vibration from the malleus in hearing?
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The oval window
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What is the central axis of the cochlea?
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The modiolus
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What is the helicotrema?
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The tip of the cochlea where the scalae vestibuli and the scalae tympani communicate.
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What causes depolarization in the hair cells of the ear?
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K+ influx causes depolarization (because the endolymph has such a high K+ concentration)
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Describe the Superior Olivary Nucleus.
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Receives projections from the cochlear nuclei. Sup. Olive detects time differences in sound arriving to the two ears.
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What is the electrical tuning of the hair cells?
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There are spontaneous electrical oscillations at the freq the cells is programmed to, then the depolarization/hyperpolarization's occur at the frequency that the cell is positioned.
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Which direction do the sterocilia move?
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Towards the kinocilium.
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What are the acoustic stria?
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Spiral ganglia fibers project to the cochlear nuclei which then project to the superior olivary nuclei on both sides. The fibers that CROSS the midline are the acoustic stria (dorsal, intermediate, and trapezoid body)
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What is the pathway for audition?
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CN VIII (vestibular and chochlear componeents) --> olivocochlear fasiculus --> Sup. olivary nucleus --> Inferior colliculus --> MGN --> Auditory cortex (superior temporal gyrus / Area 41/42).
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How is the inferior colliculus different from the superior colluculus?
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The inferior colliculus is a central part of the conscious pathway for auditory information going to the cortex. The sup. colliculus is a reflex for unconscious vision.
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What are the cortical columns of cells?
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They are columns of cortical cells in the auditory cortex. They are either summation columsn (where cells are maximally activated by sound to both ears) or suppresion columns (where cells are maximally activated by sound in only one ear).
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What happens when the auditory cortex is lesioned?
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Lose the ability for localization of sound.
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What makes up the organ of Corti?
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The hair cells of the choclea and their supporting cells.
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What determines the tonotopic representation?
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The strucural width and stiffness along the length of the organ of Corti such that higher-frequency sounds activate hair cells near the oval window, while lower freq sounds activate hair cells near the apex of the cochlea.
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What structure transmits angular acceleration information to the cochlear nerve?
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The ampullae.
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What structure provide linear acceleration and head tilt information to the cochlear nerve?
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The utricle and saccule (macule of the otolith organs).
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What contains the primary sensory neurons for the auditory pathway?
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The spiral ganglion, and the axons are sent on to the cochlear division of CN VIII to the dorsal and ventral cochlear nuclei.
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What are the dorsal and ventral cochlear nuclei wrapped around?
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The lateral aspect of the inferior cerebellar peduncle at the pontomeduallary junction.
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After the dorsal and ventral cochlear nuclei, where does the auditory pathway travel?
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BILATERALLY through a series of relays to reach the inferior colliculi, MGN, and auditory cortex.
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Why is unilateral hearing loss not seen in lesions of the CNS proximal to the cochlear nuclei?
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Because auditory information from each ear ascends bilaterally in the brainstem, with decussations occuring at multiple levels.
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