Brainscape's Knowledge GenomeTM

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


See full index

MD1 Neuroscience > Eye and Head Movements > Flashcards

Eye and Head Movements Flashcards

1
Q

What are the two components for the control of gaze?

A

Oculomotor system

Head-movement system

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

What does the oculomotor system control?

A

Moves eyes in orbit while head is still

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

What structures does the oculomotor system include?

A

Extraocular muscles

Neural pathways coordinating movement of each eye

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

What does the head-movement system control?

A

Moves eye sockets as a whole while head moves

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

What structures does the head-movement system include?

A

Vestibular system

Oculomotor system

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

What are saccadic eye movements?

A

Shifts fovea rapidly to new visual target

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

What are smooth pursuits?

A

Keeps image of moving target on fovea

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

What is vergence?

A

Moves eyes in opposite directions

  • Convergence = going cross-eyed
  • Divergence impossible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are vestibular ocular movements?

A

Holds image still on retina during brief head movements

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

What are optokinetic movements?

A

Holds image stationary during sustained head rotation/translation

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

How many extraocular muscles are there?

A

6

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

What are the rectus muscles?

A

Superior rectus
Inferior rectus
Medial rectus
Lateral rectus

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

What are the oblique muscles?

A

Inferior oblique

Superior oblique

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

Which muscle does superior oblique go underneath?

A

Superior rectus

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

Which muscle does inferior oblique go near?

A

Inferior rectus

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

What kinds of actions do extraocular muscles have?

A

Primary
Secondary
Sometimes tertiary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the primary action of superior rectus?

A

Elevation

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

What is the primary action of inferior rectus?

A

Depression

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

What is the primary action of medial rectus?

A

Adduction

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

What is the primary action of lateral rectus?

A

Abduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where do the rectus muscles insert?

A

At equator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where does the superior oblique insert?

A

Well behind equator at oblique angle close to lateral rectus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Through which structure does the tendon of the superior oblique run?

A

Trochlea

24
Q

What is the primary action of superior oblique?

A

Torsion - down and in

25
Q

Where does the inferior oblique insert?

A

Behind equator close to lateral rectus

26
Q

What is the primary action of inferior oblique?

A

Torsion - up and out

27
Q

Which muscles elevate and depress the eye when it is adducted?

A 
Elevate = inferior oblique
Depress = superior oblique
28
Q

Which muscles elevate and depress the eye when it is abducted?

A 
Elevate = superior rectus
Depress = inferior rectus
29
Q

What does the hierarchical control of eye movements involv?

A

LMNs = cranial nerves
Brainstem eye movement centres = reticular formation
Higher cortical area = frontal eye fields

30
Q

Where are the frontal eye fields?

A

Near motor cortex

31
Q

Which muscles are innervated by the oculomotor nerve?

A

Superior rectus
Inferior rectus
Medial rectus
Inferior oblique

32
Q

Which muscles are innervated by the trochlear nerve?

A

Superior oblique

33
Q

Which muscles are innervated by the abducens nerve?

A

Lateral rectus

34
Q

What is the medial longitudinal fasciculus (MLF)?

A

White matter tract > connects various cranial nerve nuclei

35
Q

Which cranial nerve nuclei does the MLF especially connect?

A

III
IV
VI
VIII

36
Q

What is the reticular formation?

A

Coordinates action of nuclei controlling eye movements

37
Q

What are the two reticular formations?

A

Pontine paramedian reticular formation

Mesencephalic paramedian reticular formation

38
Q

What does the pontine paramedian reticular formation control?

A

Horizontal gaze centre
Coordination of medial rectus and lateral rectus of each eye
Coordination of CN III and CN VI

39
Q

What does the mesencephalic paramedian reticular formation control?

A

Vertical gaze centre
Coordination of superior oblique and superior rectus of each eye
Coordination of CN III and CN IV

40
Q

What are burst neurons?

A

Fire at high frequency just before movement
Excitatory connections with ipsilateral abducens
Inhibitory connections suppress activity of contralateral abducens

41
Q

What are omnipause neurons?

A

Fire continuously except during saccade
GABAergic
Project to contralateral abducens nucleus

42
Q

What is needed for neural control of saccades?

A

Simultaneous excitation of burst neurons and inhibition of omnipause neurons

43
Q

What is the sequence of events for the horizontal neural control of saccades?

A
  1. Frontal eye fields send signal
  2. Ipsilateral excitatory burst neurons in PPRF depolarises
  3. Excitatory synapse in ipsilateral abducens nucleus
  4. Ipsilateral CN VI sends signal
  5. Lateral rectus contracts
  6. MLF sends signal from ipsilateral abducens nucleus to contralateral oculomotor nucleus
  7. Contralateral CN III sends signal
  8. Medial rectus contracts
  9. Ipsilateral inhibitory burst neurons in PPRF send signal
  10. Contralateral abducens nucleus inhibited
  11. Contralateral CN VI inhibited
  12. Contralateral lateral rectus relaxes
  13. MLF sends signal from contralateral abducens nucleus to ipsilateral oculomotor nucleus
  14. Ipsilateral oculomotor nucleus inhibited
  15. Ipsilateral oculomotor nerve inhibited
  16. Ipsilateral medial rectus relaxes
44
Q

What are eye movements ultimately driven by?

A

Behaviour

45
Q

Which upper motor neurons drive brainstem gaze centres?

A

Frontal eye fields
Posterior parietal cortex
Superior colliculus
Basal ganglia

46
Q

In which direction do frontal eye fields control saccades?

A

Contralateral direction

47
Q

What happens when there is a lesion in the medial longitudinal fasciculus?

A

Internuclear ophthalmoplegia

48
Q

What provides information about the position of the head in space?

A

Vestibular system

49
Q

What is the role of the vestibular system in controlling eye movements?

A

Coordinates position of head and eyes

50
Q

What structure gives information about head position?

A

Semicircular canals

51
Q

What structure gives information about linear acceleration?

A

Otolith organs

  • Saccule
  • Utricle
52
Q

How do the vestibular sensory receptors work?

A

Crystals and fluid inside vestibule over hair cells
Hair cells have cilia
Move head > move fluid > move cilia
Hair cells depolarise or hyperpolarise

53
Q

With which cranial nerves does the vestibulocochlear nerve communicate to coordinate eye movements when the head moves in the horizontal plane?

A

CN III and VI

54
Q

Which nucleus receives vestibular information?

A

Vestibular nuclei in medulla

55
Q

Describe the vestibular ocular reflex when you turn your head to the left?

A

Left horizontal semicircular canal senses left movement

  1. CN VIII carries info to left vestibular nucleus
  2. Excitatory signal from vestibular to abducens nucleus
  3. Right lateral rectus contracts
  4. Left MLF sends signal from right abducens nucleus to left oculomotor nucleus
  5. Left medial rectus contracts
  6. Left vestibular nucleus also sends signal to left oculomotor nucleus
  7. Left lateral rectus and right medial rectus relax

MD1 Neuroscience (55 decks)

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