Vestibular System

Question 1

hair cell

Answer 1

transducer
-do not fire APs

synapse with primary afferents

Question 2

primary afferents

Answer 2

• axons in vestibulocochlear nerve
• cell bodies in vestibular ganglion (petrous portion of temporal bone)

don’t decussate

Question 3

vestibular system

Answer 3

signals posntion and movement
-detects acceleration and gravity

series of membranous tubes
-in temporal bone

Question 4

targets of vestibular info

Answer 4

cortex
cerebellum
spinal cord
-vestibulospinal tract
cranial nerve III, IV, VI
reticular formation

Question 5

hair cell anatomy

Answer 5

tallest sterocilia - kinocilium

stereocilia on apical surface

Question 6

apical vs. basilar hair cell

Answer 6

endolymph - apical
-high K

perilymph - basilar
-low K

Question 7

baseline activity of hair cell

Answer 7

results in baseline activity of afferent nerve

increase or decrease firing

Question 8

kinocilium

Answer 8

reference

Question 9

movement of stereocilia

Answer 9

towards kinocilium - depolarization

away from kinocilium - hyperpolarization

Question 10

tip links

Answer 10

connect stereocilia

Question 11

peripheral apparatus

Answer 11

tubes in temporal bone
-nerves through internal acoustic meatus

setup orients and applies mechanical force to hair cell stereocilia

Question 12

ampulla

Answer 12

ends of semicircular ducts

where hair cells are

Question 13

otolith organs

Answer 13

where semicircular ducts attach

utricle - semicirc duct attachment
saccule

Question 14

angular acceleration

Answer 14

semicircular ducts

Question 15

linear acceleration

Answer 15

otolth organs

Question 16

utricle

Answer 16

horizontal acceleration

Question 17

saccule

Answer 17

vertical acceleration

Question 18

fluid lags

Answer 18

when head rotation occurs

Question 19

head rotation

Answer 19

tubes rotate

• endolymph lags behind
• this is detected by hair cells in ampulla

Question 20

functional pairs

Answer 20

semicircular ducts function in right/left pairs

respond oppositely in response to head turn
-gives differential signal

Question 21

differential signal

Answer 21

important because it increases sensitivity of the system

-detect minute accelerations

Question 22

otolith organs

Answer 22

sense linear acceleration/gravity

Question 23

utricle

Answer 23

horizontal

Question 24

saccule

Answer 24

vertical

Question 25

maculae

Answer 25

in utricle and saccule -has hair cells covered by otolith membranes -membrane has greater mass due to ear stones

Question 26

striola

Answer 26

division of maculae -hair cells oppositely polarized in each half oriented in curve

Question 27

each maculae

Answer 27

gives differential signal

Question 28

maculae orientation

Answer 28

every plane in x and y axis

Question 29

peripheral apparatus

Answer 29

include semicircular ducts and otolith organs | -detect acceleration and gravity

Question 30

primary efferents

Answer 30

cell bodies in vestibular ganglion

Question 31

axons of primary efferents

Answer 31

vestibulocochlear nerve most synapse in vestibular nuclei -some to cerebellum (ipsilateral)

Question 32

vestibular nuclei

Answer 32

four each side - ventral and lateral to 4th ventricle - distribute info and regulate reflexes

Question 33

vestibular nuclei activity

Answer 33

have baseline

Question 34

targets of vestibular information

Answer 34

``` cerebellum reticular formation cerebral cortex spinal cortex (LVST/MVST) cranial nerve III, VI, VI -eye movement opposite to keep image on retina ```

Question 35

vestibuloocular reflex

Answer 35

moving head allows you to focus on moving words | -maintain gaze during head movements

Question 36

path of vestibuloocular reflex

Answer 36

axons in MLF - ascend to motor nuclei of III, IV, VI

Question 37

abducent nuclei

Answer 37

cell bodies that are LMNs | -ipsilateral lateral rectus m.

Question 38

trochlear nuclei

Answer 38

superior oblique m.

Question 39

oculomotor nuclei

Answer 39

medial rectus, and others

Question 40

nystagmus

Answer 40

series of back and forth eye movements -slow one way, fast other way -can be pathologic of normal slow - VOR fast - visual motor system named for direction of fast phase

Question 41

slow nystagmus movement

Answer 41

slow - VOR

Question 42

vestibulocollic reflex

Answer 42

postural muscles of neck -extension ipsilateral to depolarized hair cells bilateral projection medial vestibulospinal tract -descending MLF/MVST

Question 43

vestibulospinal reflex

Answer 43

through lateral vestibulospinal tract ipsilateral projection to LMNs in axial and antigravity muscles of limb

Question 44

vestibular reflexes

Answer 44

based on comparison of differential signals asymmetry of signals that drives reflexes

Question 45

lesions

Answer 45

irritative | destructive - more common

Question 46

hair cells

Answer 46

can be killed with antibiotices

Question 47

fast phase nystagmus

Answer 47

away from lesion head/body tilt, leaning and falling toward lesion