ear physio Flashcards
what’s place theory?
that lower frequencies are recieved at the distal end of the cochlea and nerve signals are spatially separated
tonotopic organization?
same as place theory, just referring to the organization of frquencies across the cochlea
what neuron tract/site in the brainstem is responsible for the localization of sound?
superior olivary complex
what do olivocohclear fibers do?
filter out noise, they’re efferent fibers
what’s tinnitus?
ringing in the ears
how do hair cells cause action potentials in the vestibular system?
there’s always a tonic firing of action potentials in the nerves at about 100 APs/sec but movement of cilia towards or away from the kinocilia causes de- or hyper-polarization, respectively, via release of neurotransmitters and thereofre change firing frequency
what’s the striola?
a line of orientation in the saccule and utricle
what’s a saccade?
when the eyes snap forward form the periphery
what’s nystagmus?
it’s defined as the process of smooth eye movements to the periphery followed by sacade. the direction of nystagmus is defined as the direction of the sacade, which corresponds with the direction of percieved motion
what does the lateral vestibulospinal tract do?
go to legs to maintain balance
what does the medial vestibulospinal tract do?
maintain head stability
how does the inner ear amplify sound?
through the ratio of surface areas of the tympanic membrane to the oval window and through the lever action of the ossicles
what’s the purpose of tensor tympani m?
it tenses the malleus and reduces the sound it transmits in order to protect the cochlea from excess sound and damage, although the latency of this reflex is too long to prevent damage from short bursts of sound
where do the neurons of the cochlear nerve first synapse?
in the dorsal and ventral nuclei of the upper medulla
where do fibers from the dorsal cochlear nuclei go?
they cross the midline then ascend in the lateral lemniscus to the inferior colliculus
where do neurons from the ventral nucleus go?
each one synapses bilaterally in both inferior olivary complexes
what input does the inferior olivary complex recieve, what does it do, and where do its neurons go?
it recieves bilateral input from both ventral cochlear nuclei, it allows the temporal and volume comparison of sounds in both ears to allow for spatial recognition, and it gives off neurons that go bilaterally to synapse in both inferior colliculus
do unilateral lesions at or above the superior olivary complex cause a loss of hearing? in so, in which ear?
they don’t because each SOC sends up fibers bilaterally with input from both ears
what’s the path of auditory fibers from the inferior colliculi?
to the medial geniculate body to the primary auditory cortex
the medial geniculate body is the thalamic relay nucleus for auditory signals
primary auditory cortex is on the transverse gyrus of Heschle
what’s the efferent auditory pathway and what’s its purpose?
it’s from the superior olivary complex giving rise to the olivocochlear bundle, synapses on cochlear hair cells, prevents transmission of certain sound frequencies to block out background noises
two types of hearing loss?
sensorineural and conductive
what tumor is common at the cerebellopontine angle?
schwannomas, specifically called acoustic neuromas in these cases
