Vestibular

Question 1

where are the cells bodies of the vestibular system located

Answer 1

in the scarpa ganglion

Question 2

what is the vestibular system responsible for

Answer 2

balance, reflexive movements, head position, self motion, spatial orientation

Question 3

two main components of the vestibular labyrinth

Answer 3

membranous labyrinth (sacs filled with endolymph)
bony labyrinth (sacs filled with perilymph)

Question 4

the vestibular system is joined to which auditory structure

Answer 4

the cochlea (has the same fluids)

Question 5

what are the three types of movement in 3D space

Answer 5

translational (back n forth/ sideways)
static head tilts
rotational

Question 6

what detects static head tilts

Answer 6

primarily by the otolith organs

Question 7

what is rotational movement detected by

Answer 7

the semi circular canals

Question 8

where are the vestibular hair cells located (2)

Answer 8

in the utricle & saccule and the ampullae of the semi circular canals

Question 9

where/ what are the ampullae

Answer 9

enlargements at the base of each semi circular canal where hair cells are located

Question 10

what is the macula

Answer 10

a sensory epithelium i. the otolith organs that consists of supporting cells and hair cells

Question 11

what is the otolith membrane

Answer 11

a gel layer with calcium carbonate crystals (otoconia)

Question 12

what makes the otolith membrane heavy?

Answer 12

otoconia (calcium carbonate crystals)

Question 13

how are static head tilts detected

Answer 13

static head tilt cause the heavy otolith membrane to slide causing movements in the stereocilia of the hair cells depending on the direction you tilt your head

Question 14

describe the orientation of stereocilia in the otolith organs

Answer 14

smallest to largest towards the striola

Question 15

which plane does the utricle detect movement in

Answer 15

translational movements of the head in the horizontal plane

Question 16

which plane of movement does the saccule detect movement in

Answer 16

translational movements of the head in the vertical plane

Question 17

what is the sensory epithelium called in the semi circular canals

Answer 17

the crista

Question 18

what structure makes the barrier to endolymph in the semi circular canals

Answer 18

gel like structure called the cupula

Question 19

how is rotation of the head detected in the semi circular canals

Answer 19

rotation causes the endolymph to move in the opposite direction displacing the cupula position. leading to movement of the stereocilia of the hair cells causing hyperpolarisation or depolarisation

Question 20

how are the stereocilia orientated in the semi circular canals

Answer 20

the pair of corresponding hair cells are orientated oppositely in each ear

Question 21

when sensing angular accelerations in the head why does the discharge rate plateau in the middle

Answer 21

the fluid pushes back against the gel like cupula as it returns to its original shape

Question 22

what inputs does the vestibular nuclei integrate

Answer 22

sensory cues from vision, cutaneous (touch), and muscle spindles (proprioception)

Question 23

describe four outputs of the vestibular nuclei

Answer 23

• to spinal cord and motor neurones of limb and torso (balance & posture)
• to motor neurones of external eye muscles (stabilising gaze)
• to thalamus then vestibular cortex (perception of motion)
• cross talk to cerebellum (motor coordination)

Question 24

what is the vestibulo-ocular reflex

Answer 24

a reflex that control movement of the eye sockets when the head moves (moves eye in opposite direction to the head stabilising gaze)

Question 25

what structure controls the vestibular-cervical reflex and what is it

Answer 25

medial vestibular nucleus - signals from semi circular canals control neck muscles and head position vis this pathway

Question 26

what structures control the vestibular spinal reflex and what is it

Answer 26

lateral and medial vestibular nuclei - signals from the otoliths travel to the nuclei where nerve cell carry signals via the vestibulospinal tract to the spinal cord to stabilise posture

Question 27

describe the vestibular ascending pathways

Answer 27

through the lateral and superior vestibular nuclei to the thalamus then to the vestibular cortex