23 Lecture Auditory 2 Flashcards
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.
7up, coke down: facial nerve bundles on the top, vestibular both top and bottom and cochelar nerve on the bottom
As cochlear nucleus reaches the brainstem they bifurcate and innervate what to nuclei?
the dorsal and ventral cochlear nuclei (at the pons/medullary border lateral to the inferior cerebellar peduncle)
Where in the auditory pathway is the bilateral information shared? (nerve, nucleus, thalamus, cortex)
at the nucleus in the brainstem
What are the major pathways out of the cochlear nucleus?
trapezoid body going to the superior olive, input straight to the inferior colliculus
What is the function of the superior olive circuits?
SOC cells in these circuits compare the timing or intensity of information from the two ears to localize sounds in space
What is the path of auditory input after the superior olive?
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
What part of the cortex contains the auditory centers?
primary auditory cortex sits primarily on the transfers gyrus of the temporal lobe
What doe s MGB stand for?
median geniculate body (part of the thalamus)
True or false: a frequency map is found at every station along the auditory path.
true, there is tonotopic organization throughout
What is the function of Wernicke’s area?
language comprehension (both spoken and written), lesion causes misunderstanding of questions, speech output has normal rhythm but is meaningless
What is the function of Broca’s area?
language production, lesion causes understanding of question and inability to produce a response
What is the function of the accurate fasciculus
can typically understand language and produce speech but cannot repeat heard phrases
What are the two types of hearing loss?
conductive and sensorineural
How do you perform a Weber test and interpret its results/
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
How do you perform a Rinne test and interpret its results?
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
What is a pure tone audiogram?
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
What is presybycusis?
high frequency hearing loss usually attributed to normal aging
What type of pathology might result in normal bone conduction but low sensitivity via air conduction on an audiogram?
middle ear infection, prevents normal bone conduction, esp. with effusion.
How is auditory brainstem response used to test hearing
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
T/F otoacoustic emission can also be tested for to determine the integrity of the auditory pathway
true
What is tinnitus?
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
What is the common cause of tinnitus? (initial insult)
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
What are underlying causes that cause noise production in tinnitus?
initial insult to eh cochlea may cause rewiring of the CNS that leads to increased spontaneous activity perceived as tinnitus
What are some general advertisements to manage tinnitus?
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
