Vestibular System

Question 1

what are the vestibular sensory organs

Answer 1

semicircle canals and otolith organs

Question 2

what are the 2 otolith organs

Answer 2

utricle and saccule

Question 3

what does the vestibular system help with

Answer 3

balance, equilibrium, posture, eye movements

Question 4

semicircle canals function

Answer 4

head rotation/ angular acceleration

Question 5

otolith organs function

Answer 5

detect linear acceleration and change in head angle (tilt)

Question 6

how many semicircle canals are there

Answer 6

3

Question 7

what is the sensory apparatus in the otolith organs

Answer 7

macula

Question 8

otolith organ mechanism

Answer 8

when head moves, gravity pulls on otoliths (calcium crystals) which pull on hair cells to either hyperpolarize or depolarize

Question 9

how is the macula in the saccule orentiated

Answer 9

vertically

Question 10

how is the macula in the utricle orentiated

Answer 10

horizontally

Question 11

how to utricle and saccule detect all linear motion

Answer 11

they are perpendicular to each other and hair cells direction of depolarization split down the middle

Question 12

utricular macula direction of depolarization arrows

Answer 12

into center; horizontal

Question 13

saccule macula direction of depolarization arrows

Answer 13

away from center; up and down (vertical)

Question 14

semicircle canal fluid

Answer 14

endolymph fluid

Question 15

semicircle canal main anatomical parts

Answer 15

ampulla (bulge) and capula (gelatinous cap) connected to hair cells

Question 16

semicircular canal mechanism

Answer 16

head moves, endolymph fluid moves in opposite direction, pulls on hair cells, depolarize

Question 17

how long are hair cells depolarized before returning to baseline position: semicircular canal mechanism

Answer 17

15-30 seconds

Question 18

what are the 3 canals on each side of the head

Answer 18

horizontal, anterior vertical and prosterial vertical canals

Question 19

what are L and R horizontal canals sensitive to

Answer 19

rotation in horizontal plane

Question 20

what are L anterior and R posterior canals sensitive to

Answer 20

45 degree rotation in vertical plane anteriorly to left

Question 21

what are R anterior and L posterior canals sensitive to

Answer 21

45 degree rotation in vertical plane anteriorly to right

Question 22

push pull mechanism

Answer 22

functionally paired canals have opposing effects; when one side is depolarized and opposite is hyperpolarized

Question 23

cell bodies of vestibular nerve

Answer 23

scarpa’s ganglion

Question 24

what causes dizziness

Answer 24

when head rotation stops, inertial of endolymph fluid bends cupula in semicircular canals -> capul bends in other direction -> opposite hair cells response -> vestibular nerve on each side of head change activity

Question 25

where does the vestibular nerve (cranial nerve 8) send info

Answer 25

medial and lateral vestibular nucleus in brainstem and cerebellum

Question 26

where does lateral vestibular nucleus send info

Answer 26

1. cerebellum (movement coordination) 2. limb motor neurons (maintain posture)

Question 27

where does medial vestibular nucleus send info

Answer 27

1. VP nucleus of thalamus -> vestibular cortex 2. neck motor neurons (keep head up/ balance) 3. extraocular (eye) motor neurons (stabilize vision)

Question 28

what brain area primary processes vestibular information

Answer 28

parieto insular vestibular cortex (PIVC)