Auditory system

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Which is larger, the tympanum or the oval window? Why?: The tympanum is 15x larger than the oval window because it is receiving input from air, versus the oval window, which is receiving input from liquid.
What seperates the external ear from the middle ear?: Tympanum
What seperates the middle ear from the inner ear?: Oval window
What is in the middle ear?: 3 ossicles (incus, malleus, stapes)
What is in the inner ear?: Cochlea
How does the middle ear communicate with the inner ear?: The oval and round windows
How many turns does the cochlea have?: 2.5
How many fluid filled chambers does the cochlea have?: 3
What are the fluid filled chambers of the cochlea?: Scala vestibuli, scala media, and scala tympani
What is another name for the scala media?: Cochlear duct
What connects the scala vestibuli and the scala tympani?: helicotrema
What fluid fills the scala vestibuli and scala tympani?: Perilymph
What fluid fills the scala media?: Endolymph
What is perilymph analogous to?: Cerebrospinal fluid
What is endolymph analogous to?: Intracellular fluid
What seperates the scala vestibuli from the cochlear duct?: The vestibular membrane
What is another name for the vestibular membrane?: Reissner's membrane
What seperates the cochlear duct from the scala tympani?: Basilar membrane
Where is the organ of Corti located?: in the scala media (cochlear duct) attached to the basilar membrane
What are the 2 parts of the organ of Corti?: An inner row and 3-5 cell deep outer row of hair cells
Where are the hair cells embedded?: the tectorial membrane
What seperates the inner and outer rows of hair cells?: the tunnel of Corti
What is the tunnel of Corti filled with?: Perilymph
What is the main function of the inner hair cells?: hearing
What is the main function of the outer hair cells?: modulate (tune) sounds
What happens when fluid waves vibrate the basilar membrane and cause hair cells to bend?: Membrane potential is reduced and a neurotransmitter is released
What does this neurotransmitter do?: Initiates an action potential in a fiber of the cochlear nerve
At the base of the cochlea, the basilar membrane is -----, and responds maximally to ---- frequency waves: Narrow, high
At the apex of the cochlea, the basilar membrane is ----, and responds maximally to ----- frequnecy waves: wide, low
How does auditory sharpening make hearing more sensitive?: Outer hair cells contract and make inner hair cells more sensitive
How does auditory sharpening "tune things out"?: Hair cells are inhibited by efferent fibers of the efferent cochlear bundle
What is the full neurological pathway of high frequency sounds?: Base of the cochlea
Dorsal part of the dorsal cochlear nucleus
Medial part of the median geniculate body
Caudomedial part of the transverse temporal gyri
What is the full neurological pathway of low frequency sounds?: Apex of the cochlea
Ventral part of the dorsal cochlear nuclesu and Ventral cochlear nucleus
Lateral part of the median geniculate body
Rostrolateral part of the transverse temporal gyri
What is the origin and termination of central processes of primary auditory fibers?: Originate in spiral ganglion, terminate in dorsal and ventral cochlear nuclei
What is the origin and termination of peripheral primary auditory fibers?: Originate in spiral ganglion, terminate in the organ of Corti
Where do secondary auditory fibers originate, and what do they form?: Originate in the cochlear nuclei, form acoustic striae
Where does the dorsal cochlear nucleus receive input from?: The basal part of the cochlea
Where does the dorsal cochlear nucleus send fibers to? Via what?: Contralateral lateral lemniscus via the dorsal acoustic stria
What are the two divisions of the ventral cochlear nucleus?: Anteroventral nucleus and posteroventral nucleus
Where does the anteroventral cochlear nucleus receive input from?: apical part of the cochlea
What do fibers leaving the anteroventral cochlear nucleus form? What does it become? Where is its destination?: They form the ventral acoustic stria, which becomes the trapezoid body when it decusssates, and goes to the lateral lemniscus. Some fibers also terminate ofn the ipsilateral superior olivary nucleus
Where does the posteroventral cochlear nucleus receive input from?: apical part of the cochlea
What does the posteroventral cochlear nucleus send fibers to? Via what?: Contralateral superior olivary complex via the intermediate acoustic stria
What is the function of the intermediate acoustic stria?: Determining direction of sound
Where is the superior olivary nucleus located? Near what other structure?: In pons, near facial nucleus
What are 3 functions of the superior olivary nucleus?: 1) Sound localization via biaural interaction

2) Gives rise to the efferent cochlear bundle

3) Sends motor fibers bilaterally to stapedius and tensor tympani muscles
What fibers form the trapezoid body?: Contralateral ventral cochlear nucleus and contralateral superior olivary nucleus
What is the principal ascending auditory pathway?: Lateral lemniscus
What fibers make up the lateral lemniscus?: Ipsi AND contralateral cochlear and superior olivary nuclei
Where does the lateral lemniscus terminate?: inferior colliculus
Where does the inferior colliculus send fibers to? Via what?: Medial geniculate body via the brachium of the inferior colliculus
Where does the medial geniculate body send fibers to? Via what? Through what?: Transverse temporal gyrus cia auditory radiations through the sublentiform part of the internal capsule
Where is the primary auditory area located?: Brodmann's areas 41 and 42, of the transverse temporal gyri of Heschl, especially the middle part of the anterior gyrus
Where are low frequencies located on the ttg?: Rostrolateral
Where are high frequencies located on the ttg?: Caudomedial
Where is the auditory association area located?: Planum temporale
Why is the auditory association area important?: Higher meaning of sound, disceerning the difference between different sounds
Why is Wernicke's area important?: Language function
How does the CNS influence its own auditory input?: Via the efferent cochlear bundle
Where does the efferent cochlear bundle originate?: In the superior olivary nuclei
How does the efferenet cochlear bundle leave the brainstem?: Via the vestibular nerve
Where does the efferent cochlear bundle join the cochlear nerve? Via what? Where is it headed?: In the inner ear, the efferent cochlear bundle joins the cochlear nerve via vestibulocochlear anastomosis to reach the organ of Corti
What is the action of the efferent cochlear bundle?: Inhibit receptivity of hair cells
What are 3 things that can result in complete unilateral hearing loss?: 1) destruction of the cochlea
2) destruction of CN VIII
3) destruction of the cochlear nuclei
What will happen as a result of a unilateral lesion of a portion of the central auditory pathway?: Mild hearing loss in the contralateral ear

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Number of cards 65