Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro 2 Midterm Exam > Lecture 7: Vestibular System > Flashcards

Lecture 7: Vestibular System Flashcards

1
Q

What are the 3 main functions of the vestibular system?

A
  1. gaze stability (VOR)
  2. sensing and perceiving motions (SCC hair cells or otoliths)
  3. Postural control (VSR)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 main components of the vestibular system?

A
  1. peripheral sensory apparatus ( Membranous and bony labyrinth)
  2. a central processor ( Floculonodular lobe in cerebellum)
  3. Mechanism for motor output (ocular motor muscles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the three components of the bony labyrinth?

A

three semicircular canals, cochlea and vestibule

contains perilymph fluid that resembles CSF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are components of the membranous labyrinth?

A

membranous portions of SCC, utricle and saccule

filled with endolymph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main role of the SCC?

A

detect angular head rotation and provide sensory input about velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What structure is at the beginning of each SCC?

A

ampulla which contains specialized hair cells as well as endolymph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the term contralateral co-planar mate mean in relation to SCC?

A

planes are perpendicular to one another so in a case of hypo function one plane can assist the other will a push pull mechanism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the otoliths ?

A

refer to both the utricle and saccule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the role of the otoliths?

A

detect linear acceleration and static head tilt

Utricle- horizontal acceleration
saccule- vertical acceleration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What important structure is located in the Otoliths?

A

sensory hair cells or macula- on the medial wall of saccule and floor of utricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the role of the macula in the otoliths?

A

project gelatinous matrix which contains calcium carbonate crystals known as otoconia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of the hair cells located in the otoliths?

A

biological sensors than convert displacement due to head motion into neural firing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is each hair cell in the otolith innervated?

A

each hair cell is innervated by an afferent neuron in Scarpa’s ganglion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two different types of hair cells in the otoliths?

A

stereocillia and kinocillia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which directions of the hair cells causes excitation and inhibition?

A

deflection of endolymph results in changes in membrane potential

stereocilia (short hair cells) towards kinocillia (long hair cells) = excitation

opposite direction= inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the major components of the central processor of vestibular information?

A
  1. vestibular nuclear complex- located in pons and medulla
  2. cerebellum- major recipient of outflow from the VN, calibrates vestibular info
  3. floculonodular lobe- in cerebellum that is major role in vestibular system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What would happen if there was damage to the cerebellum?

A

vestibular reflexes would be both uncalibrated and ineffective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the two main mechanisms for motor output of vestibular system?

A

VOR and VSR- primary reflexes of vestibular system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which tract is responsible for transmitting output to the VOR?

A

medial longitudinal fasciculus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which tract is responsible for transmitting output to the VSR?

A

lateral and medial vestibulospinal tracts

21
Q

What is the main role of the VOR?

A

functions to maintain stable vision/gaze stability during head motions

works closely with the ocular muscles and visual system

one of fastest reflexes in the bosy

22
Q

What is VOR gain?

A

ratio of eye movement to head movement which should be 1.0

rate will be disrupted in vestibular pathology

23
Q

What is the main role of the VSR?

A

functions to stabilize body using otoliths output

not as quick as VOR but still a primary vestibular reflex

“corrects body if you trip over stone”

24
Q

What are three secondary vestibular reflexes?

A
  1. cervico ocular reflexes- supplements VOR, driven by neck proprioceptors
  2. Vestibulocollic Reflex- acts on neck musculature to stabilize head
  3. Visual reflex- influences vestibular circuitry
25
Q

Wy does the VOR work so well?

A

due to the pull push mechanism in coplanar SCC, during an excitation of one side of hair cells the other side will inhibit so there is not an overload of excitatory saturation

26
Q

What is vertigo?

A

issue with one’s vestibular system, sensation of motion such as spinning, tilting, translation of the either the environment or self

27
Q

What is vertigo not?

A

vertigo is not the same thing as dizziness, which is a non specific term that describes altered orientation in space which can be due to a number of different things

sx like: light headed, fainting, floating, imbalance

28
Q

What is dysequilibrium?

A

inability to maintain upright posture can result in lateral or retropulsion can be associated with non vestibular problems

29
Q

What is nystagmus?

A

involuntary back and forth movements of eyes, damage to vestibular system will cause either vertical or horizontal nystagmus

30
Q

What is a pure vertical nystagmus indicative of?

A

CNS pathology

31
Q

What is a pure horizontal nystagmus indicative of?

A

peripheral pathology, but could also be in CNS pathology

32
Q

What are two different specific types of pathological nystagmus?

A
  1. spontaneous

2. gaze evoked

33
Q

What is spontaneous nystagmus?

A

occurs in acute phase of UVH or in brainstem/ cerebellar abnormality

if peripheral inhibited by fixation, opposite if CNS

34
Q

What is gaze evoked nystagmus?

A

pt unable to main stable gaze

usually indicative structural brain lesion or med/ETOH induced (hair cells absorb ETOH)

35
Q

What is BPPV?

A

benign paroxysmal positional vertigo

most common cause of vertigo due to peripheral vestibular disorders

36
Q

How does BPPV occur?

A

occurs as a result of otoconia that become dislodged from gelatinous matrix and travels into SCC

37
Q

What are two different results from traveling otoconia?

A
  1. canalathiasis- float freely in canal

2. cupulolithiasis- otoconia fix themselves in cupola

38
Q

What is most common cause of BPPV?

A

unknown cause followed by post trauma

39
Q

What canal is BPPV most likely to occur in?

A

posterior canal 85%

40
Q

What population is BPPV more common in?

A

elderly and women, possible connection with osteoporosis and osteopenia

41
Q

What is clinical presentation of BPPV?

A

presence of vertigo, nausea, imbalance with head turns,

commonly triggered by rolling in bed, showering, driving

42
Q

What is presentation of canalathiasis?

A

onset of sx of 1-40 after moving into provoking position, horizontal, torsional upbeating CCW nystagmus

sx last less than 60 seconds

43
Q

What is presentation of cupulolithiasis?

A

immediate onset of vertigo after moving into provoking position, horizontal and torsional nystagmus, sx lasting greater than 60 seconds

44
Q

What is the gold standard test for BPPV?

A

Hall pike dix

45
Q

What is procedure of Hall pike dix?

A

start in long sitting on plinth with head in 45 degrees of rotation, drop down into supine with 30 degrees of extension, hold for 60 seconds, return to sitting with head still rotated (check nystagmus)

test both sides

46
Q

What are contraindications for a hall pike dix?

A

recent neck trauma or surgery, cervical myelopathy or radiculopathy, carotid sinus syncope, chiari malformation, severe RA, down syndrome, cervical spine instability

47
Q

What are precautions for a hall pike dix test?

A

cervical stenosis, severe kyphoscoliosis, limited cervical ROM, pagets disease, AS, LBP, SCI, obesity glaucoma, torn or detached retina

48
Q

What is alternative test for HPD?

A

side lying test used if limited cervical ROM or traditional HPD is not tolerated

subject briskly brought to side being tested with 45 degrees of rotation

49
Q

What type of nystagmus is present in anterior canal BPPV?

A

downward and torsional

Neuro 2 Midterm Exam (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions