Audition/vestibular

Front 1

cochlear nucleus divided into?

Back 1

DORSAL and VENTRAL

ventral further divided

So 3 divisions:

Anteroventral -Bilateral projection to SOC -Horizontal sound localization -Cross over only in trapezoid body


Posteroventral -Bilateral projection to SOC -Hair cell sensitivity -Decussate in both intermediate acoustic stria AND trapezoid body

Dorsal -Directly to inferior colliculus, bypasses SOC -Not well understood -perhaps important in vertical sound localization

Front 2

What is the difference between vertical and horizontal sound?

Back 2

Vertical sound is if a sound is coming from above or below you...

Horizontal sound are sounds that basically occur at the the level of our head, but either in front, to the left, right or behind the ears.

Front 3

tell me the order of structures that sound passes through

Back 3

Front 4

important cortex areas for audition?

Back 4

Primary auditory cortex is area 41/42 = A1 = On Heschl s gyrus (inside Sylvian fissure on the superior temporal lobe).

In DOMINANT hemisphere, we find Broca, Wernicke and the conduction pathway...
1. Wernicke s area --Understanding speech --Brodmann 22 --Superior temporal lobe
2. Broca s area --Producing speech (motor) --Brodmann 44, 45 --Inferior frontal lobe (Insula)

3. Conduction system --Connects Broca Wernicke/audiovisual association areas (areas 44/45 to 22, 39, 40) --arcuate fasciculus?

Like the VISUAL system, there exists a 'where' and 'what' pathway. where : spatial localization of sound, A1 to dorsal areas

what : (linguistic function??), A1 to ventral areas

Front 5

diff bw conductive hearing loss and sensironeural hearing loss?

Back 5

conductive loss is from outer and middle ear pathology, while sensironeural loss if from inner ear pathology (or higher in the auditory pathway).

Front 6

what's aphasia?

Back 6

loss of the ability to produce and/or comprehend language, due to a cortical lesion.

--Broca's is a problem with BRODUCING language, but comprehension is intact; this frustrates the patient.


--Wernicke's is a problem with COMPREHENDING language, but the spoken words are actually fluent (even though they aren't really responding to what you asked); this frustrates the doctor/family/friends, while the patient is largely oblivious.

This can come with a 'pie-in-the-sky' visual field cut, since Wernicke's is in the temporal lobe and this visual field defect comes from a lesion to Meyer's loop (also in temporal lobe!).

Conductive aphasia, a problem with the connection between Wernicke's and Broca's, is when a lesion affects the arcuate fasciculus. The primary problem is repetition, and this one is called an associative aphasia.

Front 7

what's otitis media?

which part of the ear is affected?

why is it more common in children?

Back 7

Otitis media is inflammation of the middle ear, generally from an ascending upper respiratory infection (URI), which travels from the pharynx/oropharynx into the middle ear, via the eustachian tube. --the eustachian tube is the mucous membrane pathway which opens in the middle ear at one end and at the torus tuberius at the other end, playing a role in relieving pressure build-up in the middle ear.

-3 main reasons children are more likely to get otitis media (in fact, adults should not get it ever! extremely rare!); two reasons are anatomical, one immunological.

Immune: children have a 'less refined' immune system than older children/adults.

Anatomical
1. children have a shorter eustachian tube--viruses (almost always) or bacteria (less common) do not have to travel as far into the middle ear.
2. children have a more HORIZONTAL eustachian tube than adults; the vertical tube in adults means the bugs have to go against gravity, and therefore are less likely to reach the middle ear.

Front 8

tell me the difference bw the innervation of inner hair cells and outer hair cells

Back 8

Only few VIII fibers innervate outer -One fiber might go to many outer hair cells

Most axons of VIII innervate inner -Each inner has up to 10 fibers -Each fiber goes to only one inner hair cell

Front 9

Tell me about Weber's test and Rinne's test

Back 9

Front 10

where's the first place that information from both ears is integrated?

Back 10

superior olivary nucleus (SOC)

as fibers from both the ipsilateral (directly) and contralateral (via trapezoid body) cochlear nucleus reach the SOC. At every level after this, there is bilateral input, except from the MGN. (see below). That is the MGN projects to the ipsilateral cortex (A1). NONETHELESS, it still carries information from BOTH ears to each A1, since the information had been integrated at an 'earlier' structure in the pathway.

Front 11

what part of the ear is derived from the otic placode?

Back 11

inner ear

Front 12

What is the ion most important for initiation of the transmission of auditory signals from the Organ of Corti to the central nervous system (in reference to what ion plays the largest role at the level of the hair bundle)?

Back 12

K+

Understanding the propagation of the signal at the level of the air cells is important. Make sure you understand the differences between endolymph and perilymph before learning this question. 1. Media has potential of +80mV compared to perilymph spaces. 2. Hair cells have potential of -45 to -70mV compared to perilymph spaces. 3. POTENTIAL DIFFERENCE across hair cell is 120 to 140mV --Unusual ion concentration and HUGE driving force -- K+ flows across the mechanically-gated ion channels in the hair bundle 4. UNLIKE OTHER NEURONS, K+ movement depolarizes the cell 5. Neurotransmitter release is graded (ribbon synapse), meaning an AP does not have to fire (does NOT have to reach threshold), but increasing levels of depolarization will release increasingly more neurotransmitter. 6. However, action potential IS achieved at the level of the cochlear afferents (remember, bipolar neurons with cell bodies in spiral ganglion).

Front 13

t/f

Loudness is sound intensity

Back 13

false!

Sound loudness is a subjective term describing the strength of the ear's perception of a sound. It is intimately related to sound intensity but can by no means be considered identical to intensity. The sound intensity must be factored by the ear's sensitivity to the particular frequencies contained in the sound. This is the kind of information contained in equal loudness curves for the human ear. It must also be considered that the ear's response to increasing sound intensity is a "power of ten" or logarithmic relationship. This is one of the motivations for using the decibel scale to measure sound intensity. A general "rule of thumb" for loudness is that the power must be increased by about a factor of ten to sound twice as loud. To more realistically assess sound loudness, the ear's sensitivity curves are factored in

Front 14

Pitch =

Back 14

frequency of sound


The perceived pitch of a sound is just the ear's response to frequency, i.e., for most practical purposes the pitch is just the frequency.

Front 15

Sounds may be generally characterized by _____,_____, and _____

Back 15

pitch, loudness, and quality.

Front 16

what's intensity?

Back 16

The amount of energy which is transferred to the medium is dependent upon the amplitude of vibrations of the guitar string. If more energy is put into the plucking of the string (that is, more work is done to displace the string a greater amount from its rest position), then the string vibrates with a greater amplitude. The greater amplitude of vibration of the guitar string thus imparts more energy to the medium, causing air particles to be displaced a greater distance from their rest position. Subsequently, the amplitude of vibration of the particles of the medium is increased, corresponding to an increased amount of energy being carried by the particles. This relationship between energy and amplitude was discussed in more detail in a previous unit.

The amount of energy which is transported past a given area of the medium per unit of time is known as the intensity of the sound wave. The greater the amplitude of vibrations of the particles of the medium, the greater the rate at which energy is transported through it, and the more intense that the sound wave is. Intensity is the energy/time/area; and since the energy/time ratio is equivalent to the quantity power, intensity is simply the power/area.

Front 17

the intensity of the sound wave ____ with increasing distance from the source. The decrease in intensity with increasing distance is explained by the fact that the wave is spreading out over a circular (2 dimensions) or spherical (3 dimensions) surface and thus the energy of the sound wave is being distributed over a greater surface area. The diagram at the right shows that the sound wave in a 2-dimensional medium is spreading out in space over a circular pattern. Since energy is conserved and the area through which this energy is transported is increasing, the power (being a quantity which is measured on a per area basis) must decrease. The mathematical relationship between intensity and distance is sometimes referred to as an inverse square relationship

Back 17

dec

Front 18

intraural time difference

Back 18

Front 19

Weber test?

Back 19

tuning fork in middle of the head....

Normal = equally loud on both sides
Conductive hearing loss = louder on side with hearing loss
Sensorineural hearing loss = louder on normal side

Front 20

Rinne test?

Back 20

tuning fork at mastoid process (bone), and then next to ear (in air)

Normal: sound louder by air than bone
Conductive hearing loss: sound louder by bone than air (BC>AC)
Sensorineural hearing loss: louder by air than bone (or don’t hear it) (AC>BC)

Front 21

Weber Lateralizes Left & Rinne both ears AC > BC =

Back 21

sensorineural loss Right ear

lateralizes left= you hear sound more from the left ear....so either you have a L conduction problem, or you have R sensorineural problem on the other side

with the Rinne test; both ears are normal (AC>BC) ...so there's no conduction problem...it HAS to be that you have sensorineural problem at the R


**why can you have a conduction problem on the side you hear it better? theory:

A patient with a unilateral conductive hearing loss would hear the tuning fork loudest in the affected ear. This is because the conduction problem masks the ambient noise of the room, whilst the well-functioning inner ear picks the sound up via the bones of the skull causing it to be perceived as a louder sound than in the unaffected ear. Another theory: Lower frequency sounds (as made by the 512Hz fork) that are transferred through the bone to the ear canal escapes from the canal. If an occlusion is present, the sound cannot escape and appears louder on the ear with the conductive hearing loss

Front 22

Rinne Left BC>AC & Weber's lateralized to the left =

Back 22

conductive loss on the left

Rinne Left BC> AC: means that you have a left conduction problem

Weber's lateralized to the left: means that you heard the sound better on the left....so either L conduction problem or R sensorineural problem-

What's the common possibility from both these tests: L conduction problem!

Front 23

Weber Lateralizes Right & Rinne both ears AC > BC =

Back 23

sensorineural loss Left ear

lateralizes right= you hear sound more from the right ear....so either you have a R conduction problem, or you have L sensorineural problem on the other side

with the Rinne test; both ears are normal (AC>BC) ...so there's no conduction problem...it HAS to be that you have sensorineural problem at the L

Front 24

Rinne Right BC>AC & Weber's lateralized to the right =

Back 24

= conductive loss on the right

Front 25

Rinne Left BC>AC & Weber's lateralized to the right =

Back 25

combined loss

Rinne L BC> AC: L conduction problem

Weber's lateralized to the R: either R conduction problem or L sensorineural

can't localize to one problem! multiple losses

Front 26

Rinne Right BC>AC & Weber's lateralized to the left =

Back 26

combined loss

Front 27

whenever you have one ear having BC>AC from Rinne's test, think

Back 27

conduction loss!

Front 28

what's tonotropic organization?

Back 28

Front 29

labyrinth sandwiched bw

Back 29

external acoustic meatus + internal acoustic meatus

Front 30

labyrinth sandwiched bw

Back 30

external acoustic meatus + internal acoustic meatus

Front 31

Semicircular canals:

respond to _____ acceleration
three canals:
anterior (or superior)
horizontal
posterior (or inferior)

ampulla contains ____where hair cells extend into cupula

Back 31

angular

crista ampullaris

Front 32

Otoliths
respond to ____acceleration
two otoliths: ___, ___

____ contains hair cells
hair cells extend into otoconia

Back 32

respond to linear acceleration

sacculus
utriculus
macula contains hair cells
hair cells extend into otoconia

Front 33

stereocilia (hair) are actually_____
microvilli

Back 33

Difference between microvilli and cilia….microvilli: bundles of actin…motor molecule: myosin

Cilia: made out of microtobules, motor molecules: dynein, kinesin

Front 34

when stereocilia go toward the kinocilium, ion channels on the kinocilium _____

Back 34

Front 35

what are the gray circles?

Back 35

ribbon synapses (presynaptic densities)

when membrane becomes depolarized, the Ca+ channels open

Front 36

how are hair cells excited?

Back 36

Front 37

t/f
hair cells are oriented in different directions

Back 37

false

Front 38

Endolymph remains stationary but moves relatively in the opposite direction of the angular acceleration. The cupula bends in the direction of the relative motion, bending the hair cells with it.

Back 38

Front 39

Horizontal – HCs oriented _____the utriculus
Anterior/Superior – HCs oriented ____ the utriculus
Posterior/Inferior – HCs oriented ___ the utriculus

Back 39

towards

away from

away from

Front 40

when head turns to right, the hair cells in the _____ horizontal canal fire

Back 40

right

Front 41

Back 41

j

Front 42

Back 42

remember this acronym works for conscious patients!

(only conscious patients have the fast nystagmus component)

Front 43

how is caloric testing of occular reflex different for the unconscious patient?

Back 43

Front 44

Sacculus: ____ linear acceleration
Utricle: ____ linear acceleration

Back 44

sacculus: vertical
utricle: horizontal

Hey U!

Front 45

how are otoliths excited?

Back 45

Front 46

what are some vestibular disorders?

Back 46

Front 47

Back 47

utriculus

Front 48

what's scarpa's ganglion?

Back 48

The vestibular nerve ganglion (also called Scarpa's ganglion) is the ganglion of the vestibular nerve.

Front 49

labyrinth

Back 49

Front 50

Dissecting away bony labyrinth reveals the membranous labyrinth

Back 50

Front 51

A ballet dancer spins to the left. During the spin, her eyes snap quickly to the left. This fast eye movement is

Back 51

physiological nystagmus

The fast eye movement is nystagmus which occurs in the same direction as the rotation. After the spin, postrotatory nystagmus occurs in the opposite direction.


postrotatory nystagmus: a normal finding after the animal has been rotated, with the fast phase away from the direction of rotation.


http://medical-dictionary.thefreedictionary.com/postrotatory+nystagmus

Front 52

Sound frequencies can be encoded by the organ of Corti because of the differences in properties along the _______ The base of the basilar membrane is narrow and stiff and hair cells on it are activated by ___frequencies. The apex of the basilar membrane is wide and compliant, and hair cells on it are activated by ___frequencies.

Back 52

basilar membrane

high

low

Front 53

Ascent in an elevator would activate the ____, which detect (verticle) linear acceleration

Back 53

saccules

Front 54

The semicircular canals are involved in____ or rotation. This rotation causes bending of the stereocilia toward the ____, and this bending produced depolarization of the hair cell. Hair cells of the right semicircular canal are excited (depolarized) when there is rotation to the right.

Back 54

angular acceleration

kinocilia

Front 55

where is the auditory cortex?

Back 55

Primary auditory cortex is area 41/42 = A1 = On Heschl s gyrus (inside Sylvian fissure on the superior temporal lobe).

Front 56

Broca's cortex?

Wernicke's?

Back 56

1. Wernicke s area --Understanding speech --Brodmann 22 --Superior temporal lobe
2. Broca s area --Producing speech (motor) --Brodmann 44, 45 --Inferior frontal lobe (Insula)