23 Lecture Auditory 2

Question 1

Describe the organization of the cochlear and vestibular nerves as the head toward the brainstem, include the position of the facial nerve, cochlear nerve, and inferior and superior vestibular nerve.

Answer 1

7up, coke down: facial nerve bundles on the top, vestibular both top and bottom and cochelar nerve on the bottom

Question 2

As cochlear nucleus reaches the brainstem they bifurcate and innervate what to nuclei?

Answer 2

the dorsal and ventral cochlear nuclei (at the pons/medullary border lateral to the inferior cerebellar peduncle)

Question 3

Where in the auditory pathway is the bilateral information shared? (nerve, nucleus, thalamus, cortex)

Answer 3

at the nucleus in the brainstem

Question 4

What are the major pathways out of the cochlear nucleus?

Answer 4

trapezoid body going to the superior olive, input straight to the inferior colliculus

Question 5

What is the function of the superior olive circuits?

Answer 5

SOC cells in these circuits compare the timing or intensity of information from the two ears to localize sounds in space

Question 6

What is the path of auditory input after the superior olive?

Answer 6

outs from the cochelar nucleus and superior olive are bilateral and converge on the inferior colliculus, IC outputs project ipsilaterally to the auditory thalamus (median geniculate body) before continuing on to the cortical surface

Question 7

What part of the cortex contains the auditory centers?

Answer 7

primary auditory cortex sits primarily on the transfers gyrus of the temporal lobe

Question 8

What doe s MGB stand for?

Answer 8

median geniculate body (part of the thalamus)

Question 9

True or false: a frequency map is found at every station along the auditory path.

Answer 9

true, there is tonotopic organization throughout

Question 10

What is the function of Wernicke’s area?

Answer 10

language comprehension (both spoken and written), lesion causes misunderstanding of questions, speech output has normal rhythm but is meaningless

Question 11

What is the function of Broca’s area?

Answer 11

language production, lesion causes understanding of question and inability to produce a response

Question 12

What is the function of the accurate fasciculus

Answer 12

can typically understand language and produce speech but cannot repeat heard phrases

Question 13

What are the two types of hearing loss?

Answer 13

conductive and sensorineural

Question 14

How do you perform a Weber test and interpret its results/

Answer 14

given knowledge of “the bad ear,” place a tuning fork on a bony prominence at the center of the face, if sound is loudest in good ear, sensorineural loss, if sound is louder in the bad ear, conductive loss

Question 15

How do you perform a Rinne test and interpret its results?

Answer 15

place a tuning fork on the mastoid process and then when it becomes too faint to hear, place it in the air in front of the ear, in a normal ear the sound should be heard once the fork is in the ear outside the ear; in the case of conductive loss, no sound will be heard through the air, in the case of sensorineural loss, there should be no difference in sound

Question 16

What is a pure tone audiogram?

Answer 16

can include test that evaluate air conduction and bone conduction where sounds of different pitches and loudness tested and the threshold at a certain pitch is plotted

Question 17

What is presybycusis?

Answer 17

high frequency hearing loss usually attributed to normal aging

Question 18

What type of pathology might result in normal bone conduction but low sensitivity via air conduction on an audiogram?

Answer 18

middle ear infection, prevents normal bone conduction, esp. with effusion.

Question 19

How is auditory brainstem response used to test hearing

Answer 19

parts of the neural pathway that conduct the auditory information respond to stimulus with characteristic electrical activity which can be measured as a key to hearing deficits if not comparatively normal (waves for auditory nerve, cochlear nucleus, superior olive, inferior colliculus are the most consistent response) **helpful to distinguish nuclei from nerve disfunction

Question 20

T/F otoacoustic emission can also be tested for to determine the integrity of the auditory pathway

Answer 20

true

Question 21

What is tinnitus?

Answer 21

perception of sound in the ears or head where no external source is present; objective tinnitus: sound can be observed by physician where as with subjective the source of the sound cannot be observed

Question 22

What is the common cause of tinnitus? (initial insult)

Answer 22

most tinnitus conditions result form damage to hair cells or CN VIII damage due to loud noise exposure; other causes include obscuring ear canal, otosclerosis, high blood pressure, allergies, diabetes, some drugs, etc

Question 23

What are underlying causes that cause noise production in tinnitus?

Answer 23

initial insult to eh cochlea may cause rewiring of the CNS that leads to increased spontaneous activity perceived as tinnitus

Question 24

What are some general advertisements to manage tinnitus?

Answer 24

avoid loud noise, control blood pressure, reduce salt intake, avoid coffee, tobacco, tea, soda, exercise regularly, avoid fatigue and they to learn to ignore hearing the noise

Question 25

What is meniere’s disease?

Answer 25

disorder of the inner ear that causes vertigo, imbalance, nausea/vomitting, ringing ear, fluctuating hearing loss

Question 26

What is the proposed cause of Meniere’s disease?

Answer 26

dilated membranous labyrinth (called hydrous), could be caused by rupture of the membrane and mixing of endo and perilyph or drainage system blockage via the endolymphatic duct sac

Question 27

What are the working parts of a cochlear implant?

Answer 27

microphone picks up the sound and a speech processor converts that into and electrical code that stimulates specific portions of the cochlea corresponding to the correct frequencies

Question 28

True or false: cochlear implant completely restores lost hearing

Answer 28

False, the active zones on the electrode stimulating the cochlea are much fewer than the natural cochlea– the more sites the higher the auditory resolution.