ear physio

Question 1

what’s place theory?

Answer 1

that lower frequencies are recieved at the distal end of the cochlea and nerve signals are spatially separated

Question 2

tonotopic organization?

Answer 2

same as place theory, just referring to the organization of frquencies across the cochlea

Question 3

what neuron tract/site in the brainstem is responsible for the localization of sound?

Answer 3

superior olivary complex

Question 4

what do olivocohclear fibers do?

Answer 4

filter out noise, they’re efferent fibers

Question 5

what’s tinnitus?

Answer 5

ringing in the ears

Question 6

how do hair cells cause action potentials in the vestibular system?

Answer 6

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

Question 7

what’s the striola?

Answer 7

a line of orientation in the saccule and utricle

Question 8

what’s a saccade?

Answer 8

when the eyes snap forward form the periphery

Question 9

what’s nystagmus?

Answer 9

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

Question 10

what does the lateral vestibulospinal tract do?

Answer 10

go to legs to maintain balance

Question 11

what does the medial vestibulospinal tract do?

Answer 11

maintain head stability

Question 12

how does the inner ear amplify sound?

Answer 12

through the ratio of surface areas of the tympanic membrane to the oval window and through the lever action of the ossicles

Question 13

what’s the purpose of tensor tympani m?

Answer 13

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

Question 14

where do the neurons of the cochlear nerve first synapse?

Answer 14

in the dorsal and ventral nuclei of the upper medulla

Question 15

where do fibers from the dorsal cochlear nuclei go?

Answer 15

they cross the midline then ascend in the lateral lemniscus to the inferior colliculus

Question 16

where do neurons from the ventral nucleus go?

Answer 16

each one synapses bilaterally in both inferior olivary complexes

Question 17

what input does the inferior olivary complex recieve, what does it do, and where do its neurons go?

Answer 17

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

Question 18

do unilateral lesions at or above the superior olivary complex cause a loss of hearing? in so, in which ear?

Answer 18

they don’t because each SOC sends up fibers bilaterally with input from both ears

Question 19

what’s the path of auditory fibers from the inferior colliculi?

Answer 19

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

Question 20

what’s the efferent auditory pathway and what’s its purpose?

Answer 20

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

Question 21

two types of hearing loss?

Answer 21

sensorineural and conductive

Question 22

what tumor is common at the cerebellopontine angle?

Answer 22

schwannomas, specifically called acoustic neuromas in these cases