Test 2: Auditory Pathway Flashcards Preview

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Flashcards in Test 2: Auditory Pathway Deck (34):
1

What CN is responsible for hearing and how does it happen?

Cochlear nerve CN VIII
-one of two nerves from CNVIII

Audition transduced by mechanoreceptors in cochlea

2

What are the two primary pathways roles?

Detect sound in space
Localize sound in space

3

What are the features of the inner ear vs. middle ear?

Middle ear:
-starts at tympanic membrane
-stapes, maleus, incus for amplification
-lesions=conductive hearing loss

Inner ear:
-starts at oval window (base of stapes)
-cochlea
-lesions=senorineural hearing loss

4

What are the initial receptors of auditory pathways

mechannoreceptors in cochlea

5

What are the 3 champers of the cochlea

1. Scala media:
-fluid high in K; influx causes depolarization
-in organ of corti- sensory neuron 1CB

2. Scala vestibule:
-superior compartment
-perilymph

3. Scala tymponi:
-inferior compartment
-perilymph

6

What does perilymph in scala vestibule and tymponi do?

waves ossilate the basilar membrane
bends hair cells
starts transduction

7

What do the inner hair cells do?

On organ of corti- basilar membrane
-cilia imbedded in tectoral membrane that forms roof
-synapse on cochlear neurons

8

How do the sound waves go through the middle ear?

enter auditory canal of middle ear-> deflect tympanic membrane -> mobilzie small bones to amplify
MECHANICAL energy

9

How do sound waves transduce in the inner ear?

Sound waves into fluid wave in perilymph
deflects basilar membrain -> shear force bends tectoral hair cells
Bending hair cells-> midifies voltage -> depolarize BIPOLAR COCHLEAR NEURONS

10

What are the characteristics of 1 neurons?

Cochlear sensory neurons from CNVIII
CB in cochlear spinal ganglion
-transmit auditory signals to dorsal/ventral cochlear nerve
-pontemedullary junction in cerebellar peduncles

11

What is the difference in mechanical vs. electrical transduction?

Electrical: ossilation of basilar membrain and sterocillia in tectoral

Mechanical: fluid waves press stereocil into tectoral membrane- bends hair calls

12

What is the totonic map in the cochlea?

High frequency sounds hear close to oval window- more by middle ear

Low frequency sounds hear deeper by apex

13

How many neurons make up the most direct auditory pathway?

4

14

Where are the 2CB

Ventral or dorsal nuclei depending on sound frequency

15

What do the ventral cochlear nuclei neurons do

Contribute to horizontal path for LOCALIZATION
-relay bilaterally for redundancy
-ascend superior olives
-some decussate in basis pons in trapezoid body

16

What occurs at the level of the superior olives in the ventral pathway?

L/R comparison, timing, and amplitude
-project bilaterally

17

What do the dorsal cochlear nuclei neurons do

decussate in pons
PERCEPTION of sound

18

Both ventral and dorsal nuclei ascent in what tract?

Lateral leminiscus tract
-go to inferior colliculi to combine with other auditory input: reflexes, bilateral communication

19

Where are the 3CB

Inferior colliculous
-ascend in Brachium of inferiour colliculs to MGN

20

Where are 4CB

MGN thalamus
-form auditory radiations. go through posterior limb to A1

21

What is the difference between A1 and A2

1: concious detection of initial states of sound analysis

2: higher cortexes of receptive language/recognition in wernickes-BA22

22

What makes up the primary auditory cortex

transverse temporal gyrus
superior tempoeral gyrus

23

Where are different pitches heard

High hz/pitch deeper in cortex
Low hz/pitch more lateral in cortez

24

What is the BA number for A1

41

25

What neurons are traveling in the lateral lemniscal tract?

DGN to L/R superior olives

26

What neurons are traveling in the brachium of inferior colliculus

Inferior colliculous CB to MGN

27

What jobs do arcuate vs uncinate fasciulus do?

arcuate: where? spacial
uncinate: what? language

28

What blood supply feeds the cochlear nerve (caudal pons)

AICA

29

What supplys the medulla

vertebral- most
PICA- rostral

30

What supplies the caudal pons

Basilar- most
AICE- caudal

31

What supplies the rostral pons

basilar-most
-SCA dorsal

32

What supplies the caudal midbrain

basilar
-SCA and PCA

33

What supplies the rostral midbrain

PCA-most
Post comm, basilar, SCA

34

What supplies the MGM and auditory radiations?

Ant choiroidal: internal capsule
PCA: MGN and LGN
MCA: A1