Unit 2: Vestibular System Flashcards
1
Q
The vestibular system is responsible for helping to monitor the
A
Orientation of the head in 3-dimensional space
2
Q
Vestibular data is collected and integrated into the CNS with visual and proprioceptive data used to:
A
- Maintain general body equilibrium
2. Coordinate eye movements with movements of the head
3
Q
Structures within the vestibular system include
A
- Apparatus within the inner ear
- Vestibular division of CNVIII
- CNS pathways
4
Q
The saccule and utricle are dilations of the membranous labyrinth and filled with
A
Endolymph
5
Q
The vestibule and semicircular canals are within the
A
Osseous labyrinth
6
Q
The utricle, saccule and semicircular ducts are within the
A
Membranous labyrinth
7
Q
Along the wall of each saccule and utricle there is a “patch” of sensory epithelium (the vestibular receptors) called:
A
Maculae
8
Q
Specialized mechanoreceptors that monitor the position of the head (static and kinetic)
A
Maculae
9
Q
The stereocilia (hair cells, aka sensory cells) project from the apical edge with one long single “hair” called
A
Kinocilium
10
Q
If hair cells/stereocilia bend toward the kinocilia, what happens to firing rate?
A
Increases firing rate
11
Q
If hair cells/stereocilia bend away from the kinocilia, what happens to firing rate?
A
Decrease firing rate
12
Q
The gelatinous membrane that contains otoliths is called
A
Otolithic membrane
13
Q
Crystals comprised of protein and calcium carbonate:
A
Otoliths
14
Q
What innervates the base of each hair cell?
A
Dentrites of 1˚ vestibular neurons
15
Q
Maculae best monitor:
A
Tilting head movements and acceleration and deceleration phases of linear movement
16
Q
How many semicircular ducts per inner ear?
A
3
17
Q
The posterior semicircular duct is in the ____ plane and monitors information in the _____ plane
A
Vertical; vertical
18
Q
The anterior (superior) semicircular duct is in the ____ plane and monitors motion in the ___ plane
A
Vertical; vertical
19
Q
The lateral (horizontal) semicircular duct slopes posteriorly and inferiority 30˚ to the ______ plane and monitors motion in the _______ plane
A
Horizontal; horizontal
20
Q
Semicircular ducts filled with:
A
Endolymph
21
Q
Semicircular ducts surrounded by
A
Perilymph
22
Q
Each of the 3 semicircular ducts has a dilation/bulbous end called
A
Ampulla
23
Q
Along the wall of each ampulla in the semicircular ducts, there is a patch of specialized sensory epithelium called
A
Crista ampullaris (plural =cristae)
24
Q
Cristae ampullaris are what kind of receptors?
A
Mechanoreceptors
25
Cristae ampullaris monitor what kind of movement?
Rotational/angular head movement
26
The gelatinous membrane in which hairs of the crista ampullaris are called embedded in
Cupula
27
1˚ vestibular neuron cell bodies are located in
Vestibular/Scarpa’s ganglion
28
Cristae ampullaris change their excitability (static discharge) when head undergoes what kind of motion?
Angular/rotational
29
Head rotates/moves to the RIGHT, the RIGHT duct rotates to the ____, and the endolymph moves to the ____.
Right; left
| Endolymph lags
30
Ampullopetal
Movements facilitates cristae ampullaris (aka endolymph moves toward cristae)
31
Ampullofugal
Movement inhibits cristae ampullaris (aka endolymph moves away from cristae)
32
Decreases discharge movement of cristae / inhibition of the crista ampullaris
Ampullofugal
33
Increase discharge movement of cristae / facilitation of crista ampullaris
Ampullopetal
34
Rotation of head to the right (acceleration phase). What is the endolymph doing in the right vs left lateral ducts?
Right lateral duct endolymph is moving through ampulla and into utricle = ampullopetal flow
Endolymph in left lateral duct flows through ampulla into duct = ampullofugal flow
35
Peripheral processes of the primary vestibular neurons innervate hair cells of the:
Cristae ampullaris and maculae
36
Central processes of vestibular neurons enter the brainstem as part of the CN
VIII
37
Some central axons of vestibular pathway enter the ______ through ICP
Cerebellum
38
Most central axons of the vestibular pathway will synapse in the
Vestibular nuclear complex
39
The vestibulospinal tract is ipsilateral or contralateral tract?
Ipsilateral
40
The descending medial longitudinal fasciculus pathway is a ipsilateral/bilateral pathway
Bilateral - includes axons from the ipsilateral and contralateral vestibular nuclear complex
41
The vestibular nuclear complex is located in:
The floor of the IV ventricle in the pons and medulla AKA the rhomboid fossa
42
What are the 2 tracts/pathways that project from the vestibular nuclear complex into the spinal cord?
Vestibulospinal Tract and Medial Longitudinal Fasciculus (MLF)
43
Descending Medial Longitudinal Fasciculus (MLF) help
Regulate tone of neck muscles in order to maintain balance of head as it moves through space
44
Ascending Medial Longitudinal Fasciculus (MLF) fibers influence activity of cranial nerve(s):
VI, IV, III
45
Ascending Medial Longitudinal Fasciculus (MLF) help
Both eyes move together in parallel or ‘conjugate’ fashion
46
Vestibular data also projects to the cerebellum via VIII nerve directly to the
Vestibulocerebellum AKA archicerebellum
47
Vestibular data that projects to the cerebellum project through what structure?
Inferior cerebellar peduncle (AKA restiform body)
48
Cell bodies of primary sensory vestibular neurons/bipolar neurons comprise this ganglion:
Vestibular ganglion aka Scarpa’s ganglion
49
Peripheral processes of vestibular neurons innervate:
Hair cells of cristae ampullaris and maculae
49
The tips of “hair” cells in the vestibular system are embedded in what?
Otolithic membrane or cupula
49
Primary vestibular neuron cell bodies are located where?
Vestibular ganglion (aka Scarpa’s ganglion)
50
What innervates the base of each hair cell?
Dendrites of primary vestibular neurons whose cell bodies are located in the vestibular ganglion
51
Is the vestibulospinal tract continuous or discontinuous through the spinal cord
Continuous - it extends the entire length of the cord
52
Projections from the vestibular nuclear complex synapse on interneurons or motor neurons that innervate what?
postural muscles - such that when the head is moved, body equilibrium is maintained
53
Primary vestibular neuron axons that project into the medial longitudinal fasciculus (MLF) synapse in cervical cord segments on interneurons or motor neurons that innervate what?
neck muscles - helps to regulate tone of neck muscles in order to
maintain the balance of the head as it moves through space
54
The vestibulocerebellum (archicerebellum) utilizes the information that is receives to do what?
influence the activity of muscles used in posture and balance
55
What areas of the cerebrum receive vestibular data?
Parietal and temporal lobes and insula
56
The vestibular pathways to the cerebrum contribute to what conscious awareness?
Conscious awareness of the precise position of the head in space
57
When an individual, walking in a straight line, turns to the right, what happens to endolymph flow in the right lateral duct and how does it affect the discharge of the unilateral crista?
It is ampullopetal which will cause the discharge of the unilateral crista to increase.
58
When an individual, walking in a straight line, turns to the right, what happens to endolymph flow in the left lateral duct and how does it affect the discharge of the unilateral crista?
It is ampullofugal which will cause the discharge of the unilateral crista to decrease.
59
vestibular data from the inner ears projects to the _______ and modifies the activity of central vestibular pathways which are ________ and _______.
- vestibular nuclear complex
| - Vestibulospinal tract, Medial longitudinal fasciculus tract
60
As the head rotates to the right, vestibular data drives a ________ that enables the eyes to maintain visual fixation on stationary objects as the head is moving.
vestibulo-ocular or vestibulokinetic reflex
61
As part of the vestibulo-ocular or vestibulokinetic reflex, as the head rotates to the right, the eyes will initially move slowly to the ________. This is called _______ phase of the reflex?
- left
| - slow drift
62
A slow drift reflex of the eyes to the left, requires facilitation of the right CN ______ that innervates the right ______ muscle and facilitation of the left CN ______ that innervated the left ______ muscle.
- 3, medial rectus
| - 6, lateral rectus
63
The slow drift phase of the reflex is dependent on the _________ and is mediated by __________.
- vestibular data from the inner ear
| - the ascending MLF
64
After the slow drift phase of the reflex, the eyes quickly move to the ________ in the fast drift phase of the reflex.
Opposite direction
65
A fast drift reflex of the eyes to the right, requires facilitation of the right CN ______ that innervates the right ______ muscle and facilitation of the left CN ______ that innervated the left ______ muscle.
- 6, lateral rectus
| - 3, medial rectus
66
Is the fast drift phase of the reflex driven by vestibular data?
No, it is considered a corrective maneuver
67
The pattern of slow and fast drift movements of the eyes are collectively known as what?
Nystagmus
68
The direction of nystagmus is designated as the direction of which component of the reflex?
The fast component
- thus with rotation of the head to the right, nystagmus is to the right
69
What are two test used for testing the integrity of the vestibular system?
- rotation test
| - caloric test
70
What are the steps of the rotation test?
- patient seated in swivel chair with head tilted 30 degrees forward to get the lateral semicircular ducts in the horizontal plane
- patient is rotated at a constant velocity for about 10-15 turns so that endolymph is moving at the same speed as the head and lateral semicircular ducts and crista ampullaris receptors have reached a static discharge rate
- chair is stopped and patient is asked to stand and point at a distant stationary object
- observe and evaluate the patient during the post rotation phase
71
During the post rotation phase of the rotation test of the vestibular system, the patient will fall to the ______ (same/opposite) side of rotation in the swivel chair
Same
72
During the post rotation phase of the rotation test for vestibular system, the CNS thinks the head/body is rotation to the _______ (same/opposite) side of rotation in the swivel chair.
Opposite
73
During the post rotation phase of the rotation test for vestibular system, when attempting to point to a distant object, the patient will past point to the _______ (same/opposite) side of rotation in the swivel chair.
Same
74
What are the steps of the caloric test of the vestibular system?
- tilt patient’s head backwards 60 degrees to place lateral ducts in vertical position
- irrigate the external auditory canal of one ear with either warm or cold water
- observe and record normal nystagmus response of the caloric test (COWS)
75
The mechanism of the caloric test is that water in the ear will induce convection current in the endolymph. Cold water will cool the endolymph, reduce fluid level and cause _________ movement of the endolymph and ipsilateral crista discharge rate to ________ . The brain interprets this information as rotation of the head to the ________ (opposite/same) side.
- Ampullofugal
- decrease
- opposite
76
The mechanism of the caloric test is that water in the ear will induce convection current in the endolymph. Warm water will warm the endolymph, increase fluid level and cause _________ movement of the endolymph and ipsilateral crista discharge rate to ________ . The brain interprets this information as rotation of the head to the ________ (opposite/same) side.
- Ampullopedal
- Increase
- same
77
Caloric Test: Cold water. What does the endolymph do?
Cools, reduced fluid levels.
78
Caloric Test: Cold water. What is the movement of ipsilateral endolymph in ipsi semicircular duct?
Ampullofugal
79
Caloric Test: Cold water. Does the discharge rate increase, decrease or stay the same in the ipsilateral crista?
Decrease
80
Caloric Test: Cold water. Brain interprets this information as rotation of the head to what side?
Opposite side — left
Ex. Right ear so left rotation interpretation
81
Caloric Test: Cold water. Will cause a slow drift to what side?
Ipsilateral — right
Ex. Right ear, right slow drift
82
Caloric Test: Cold water. Will cause a fast drift to what side
Contralateral — left
Ex. Right ear, left fast drift
83
Caloric Test: Cold water. Will cause what kind of nystagmus?
Contralateral — left
Ex. Right ear, left nystagmus
84
Caloric Test: Cold water. Patient will fall to what side?
Ipsilateral side — right
Ex. Right ear, fall to right
85
Caloric Test: Cold water. Patient will past-point to what side?
Ipsilateral — right
Ex. Right ear, past-point right
86
Caloric Test: Warm water. What happens to ipsilateral endolymph?
Warms, increases fluid level
87
Caloric Test: Warm water. What kind of movement of endolymph in ipsilateral semicircular duct?
Ampullopedal
88
Caloric Test: Warm water. discharge rate of ipsilateral crista?
Increased
89
Caloric Test: Warm water. Brain interprets this movement as rotation of head to what side?
Same side
Ex. Right ear, right rotation
90
Caloric Test: Warm water. Slow drift?
Contralateral
Ex. Right ear, left slow drift
91
Caloric Test: Warm water. Fast drift?
Ipsilateral
Ex. Right ear, right fast drift
92
Caloric Test: Warm water. Nystagmus
Ipsilateral nystagmus
Ex. Right ear, right nystagmus
93
Caloric Test: Warm water. Patient falls to what side?
Contralateral
Ex. Right ear, falls left
94
Caloric Test: Warm water. Patient past-points to what side?
Contralateral
Ex. Right ear, past-point left
