Auditory Pathways

Question 1

How is tone frequency detected relative to the cochlea?

Answer 1

High frequency tones register close to base of cochlea

Low frequency tones register distal to base of cochlea

Question 2

All fibers in the cochlear nerve synapse in the cochlear nuclei on the _______ side

Answer 2

Ipsilateral

Question 3

As cochlear info ascends to the auditory cortex, it is distributed through multiple parallel pathways that ultimately converge in the ______

Answer 3

Inferior colliculus

Question 4

From the midbrain, auditory info is conveyed from the inferior colliculus to the _________ nucleus of the thalamus, then through the sublenticular limb of the _____ _____ to the auditory cortex

Answer 4

Medial geniculate; internal capsule

Question 5

The spiral ganglion has 2 types of bipolar sensory neurons. What is the difference between the two?

Answer 5

Type I cells (90-95%) — 20+ radial branches synapse with 1-2 inner hair cells, respond to narrow frequency range

Type II ganglion cells — widely distributed peripheral processes that traverse the tunnel of Corti and synapse with 10+ outer hair cells. More sensitive to low-intensity sounds, less precisely tuned to frequency

Question 6

As cochlear nerve fibers enter the brainstem at the cerebellopontine angle, they divide into ascending bundles and descending bundles.

Ascending bundles synapse in the _____ part of the ______ cochlear nucleus.

Answer 6

Anterior; anterior

[most fibers from anterior cochlear nucleus course anterior to restiform body part of inferior cerebellar peduncle to form the trapezoid body]

Question 7

As cochlear nerve fibers enter the brainstem at the cerebellopontine angle, they divide into ascending bundles and descending bundles.

Descending bundles synapse in the _____ part of the ______ cochlear nucleus AND the _______ cochlear nucleus

Answer 7

Posterior; anterior; posterior

[projections from posterior cochlear nucleus and some from anterior cochlear nucleus course posteriorly over the restiform body as the posterior acoustic stria and decussate in the pontine tegmentum before joining the lateral lemniscus]

Question 8

5 nuclei associated with primary auditory pathway

Answer 8

Cochlear nuclei
Superior olivary nucleus
Trapezoid body
Nuclei of lateral lemniscus
Inferior colliculus

Question 9

Where is the first point in the primary auditory pathway at which decussation occurs?

Answer 9

Trapezoid body

Question 10

It is possible to have a second order neuron proceed all the way up the auditory pathwway via the trapezoid body, bypassing the _____ nucleus and the nucleus of the _____ ____

Answer 10

Superior olivary; lateral lemniscus

Question 11

3 primary fiber bundles that transmit info in the primary auditory pathway

Answer 11

Trapezoid body
Acoustic stria
Lateral lemniscus

Question 12

What type of hearing loss results from damage to the cochlea or cochlear root of CN VIII

Answer 12

Sensorineural loss

Question 13

Which type of hearing loss has no air or bone conduction when tested with Weber/Rinne?

Answer 13

Sensorineural

Question 14

What type of hearing loss results from disease or damage to either external or middle ear?

Answer 14

Conductive hearing loss

Question 15

With conductive hearing loss, _____ conduction is greater than _____conduction on Weber/Rinne test

Answer 15

Bone; air

Question 16

During the Weber test, tuning fork is placed on the forehead or mastoid process. If sound lateralizes to the left ear, what are the 2 possible deficits indicated?

Answer 16

Conductive deficit in left ear

Sensorineural deficit in right ear

Question 17

Result of unilateral dmaage to cochlear n. or cochlear nucleus

Answer 17

Ipsilateral monaural deafness

Question 18

Result of unilateral damage at or above superior olivary complex

Answer 18

Inability to localize sounds, inattention to stimuli on contralateral side, or inability to follow conversations in a noisy room

Question 19

What condition results from damage to the cochlear nuclei or the central pathways that relay auditory info to the auditory cortex?

Answer 19

Central deafness

Question 20

Order of events in primary auditory pathway

Answer 20

Cochlea
Spiral ganglion
[CN VIII]
Cochlear nucleus
[trapezoid body]
Superior olivary complex
Nucleus of lateral lemniscus
[lateral lemniscus]
Inferior colliculus
[brachium of inferior colliculus]
Medial geniculate body
Auditory cortex

[brackets = fibers between synapses]

Question 21

The primary auditory cortex communicates with the auditory association cortex via the ____ ____

Answer 21

Arcuate fasciculus

Question 22

The primary auditory cortex is located where?

Answer 22

Transverse gyri of Heschl

Brodmann area 41

Question 23

The auditory association cortex surrounds the primary auditory area. It is located mainly in the _____ portion of the superior temporal gyrus and corresponds to Brodmann area _____

Answer 23

Posterior; 22

Question 24

Sound localization based on timing is recognized by what component of the auditory pathway?

Answer 24

Medial superior olivary nucleus

[ex: talking to left ear, left medial superior olivary nucleus is hit first and trapezoid body on left will send glycine (inhib NT) to right side]

Question 25

Localization based on sound intensity is recognized by what component of the auditory pathway?

Answer 25

Lateral superior olivary nucleus

[this is also known as coincidence detection]

Question 26

What component of the auditory pathway has a protective mechanism to dampen sound from medial to lateral?

Answer 26

Olivocochlear bundle

Question 27

Which brodmann areas are associated with reflex to turn head towards location of sound?

Answer 27

22
42
41

Question 28

A lesion in which portion of the afferent acoustic pathway would lead to single-sided deafness?

Answer 28

Cochlear nucleus

Question 29

Condition in which ability to hear sound is maintained but pt is unable to put meaning with it

Answer 29

Auditory agnosia

Question 30

Result of damage to broca’s area

Answer 30

Understand speech but cannot formulate words to respond

Question 31

Location of brocas area

Answer 31

Brodmanns 44 and 45

Located in pars opercularis and pars triangularis of inferior frontal gyrus — connected with auditory association cortex via arcuate fasciculus

Question 32

Result of damage to wernicke’s area

Answer 32

Hear sound but cannot interpret speech

Question 33

Location of wernicke’s area

Answer 33

Auditory association cortex — primarily in posterior portion of superior temporal gyrus, Brodmann area 22

Question 34

Condition in which auditory comprehension is intact with fluent speech, but poor speech repetition

Answer 34

Conduction aphasia

Question 35

Conduction aphasia usually involves damage to _____ _____ and left parietal region

Answer 35

Arcuate fasciculus