Visual Motor Systems

Front 1

What is the purpose of eye movements?

Back 1

Foveation

Front 2

What is the fovea?

Back 2

The center of the macula

Front 3

What is the fovea used for?

Back 3

-Fixating on objects
-High acuity vision

Front 4

6 functional classes of eye movements:

Back 4

1. Smooth pursuit
2. Saccades
3. Vestibular
4. Vergence
5. Optokinetic
6. Fixation

Front 5

What is Smooth pursuit?

Back 5

Eye movement that holds the image of a moving target steady on the fovea

Front 6

What are Saccades?

Back 6

Eye movements that bring objects of interest in the peripheral visual field onto the fovea.

Front 7

What is Vestibular eye movement?

Back 7

Eye movements that maintain foveation during brief head rotations and translations

Front 8

What is Vergence?

Back 8

When the eyes move in opposite directions to maintain foveation as objects approach or recede.

Front 9

What is optokinetic eye movement?

Back 9

Eye movement that stabilizes the image of the surrounding visual scene during sustained head rotations.

Front 10

What does optokinetic eye movement take over for?

Back 10

The vestibular eye movements that become insufficient to maintain foveation during sustained spinning.

Front 11

What is fixation?

Back 11

Maintaining foveation on a stationary object.

Front 12

how do you test for smooth pursuit eye movements?

Back 12

By testing ability to follow a moving target.

Front 13

How do you test for saccades?

Back 13

By testing the ability of a stimulus in the peripheral field to make the eyes shift toward it.

Front 14

How do you test for Vestibular eye movements?

Back 14

By checking to see if the eyes move against the direction of head rotation (normal), or with it (abnormal).

Front 15

How do you test for Vergence?

Back 15

By putting your fingers in front of the nose and moving closer or away.

Front 16

How do you test for optokinetic eye movements?

Back 16

By using optokinetic tape to elicit nystagmus

Front 17

How do you test for Fixation?

Back 17

Look to see if the patient can maintain a stable gaze.

Front 18

What are the horizontally acting eye muscles? What is each one's action?

Back 18

-Medial rectus - adduction
-Lateral rectus - abduction

Front 19

What are the actions of Superior Rectus?

Back 19

-Elevation
-Incycloduction
-Adduction

Front 20

What is incycloduction

Back 20

Intorsion - rotating the top of the eye toward the nose

Front 21

What are the actions of Inferior Rectus?

Back 21

-Depression
-Extorsion
-Adduction

Front 22

Are the eyeballs sitting in the eye sockets in line with the axis of the socket?

Back 22

No; they're at a 23' angle off from it.

Front 23

What does the degree of alignment with the eye socket mean for testing oculomuscles?

Back 23

You have to align them differently to be testing the pure function of each muscle.

Front 24

What is the primary action of superior oblique? 2'/3' actions?

Back 24

1. Intorsion
2. Depression
3. Abduction

Front 25

What is the primary action of inferior oblique? 2'/3' actions?

Back 25

1. Extorsion
2. Elevation
3. Abduction

Front 26

What muscles are you using when you look up and to the right?

Back 26

SR in the right eye
IO in the left eye

Front 27

What muscles are you using when you look straight up?

Back 27

SR/IO in both eyes

Front 28

What muscles are you using when you look down and to the right?

Back 28

IR in the right eye
SO in the left eye

Front 29

pneumonic for looking straight down:

Back 29

IRSO
in both eyes

Front 30

What does the superior division of CN III innervate?

Back 30

-Levator palpebrae
-Superior rectus

Front 31

What does the inferior division of CN III innervate?

Back 31

Everything else:
-Medial rectus
-Inferior rectus
-Inferior oblique
-Sphincter pupillae
-Muscularis ciliaris

Front 32

What does CN IV innervate?

Back 32

Superior oblique

Front 33

What does CN VI innervate?

Back 33

Lateral rectus

Front 34

What surrounds all the extraocular muscles?

Back 34

The annulus of zinn

Front 35

What does Hering's Law say?

Back 35

If you look to the left, the left lateral rectus and right medial rectus fire equally and at the same time.

Front 36

What happens if you put your finger on your nose?

Back 36

Both medial rectus fires fire at the same rate.

Front 37

What happens if you tilt your head to the left?

Back 37

-Left eye intorts via SO/SR
-Right eye extorts via IO/IR

Front 38

How are the eyes contained in the eye sockets?

Back 38

By orbital pulleys that contain smooth muscle that aids in eye movements and keeps the eyes in a straight forward position.

Front 39

What are the extraocular muscle pulleys?

Back 39

Fibroelastic structures that function like the trochlea.

Front 40

What do the extraocular muscle pulleys function to do?

Back 40

Fix the position and pulling direction of the rectus muscles.

Front 41

Where does the global layer of the rectus muscles insert?

Back 41

On the eyeball

Front 42

Where does the orbital layer of rectus muscles insert?

Back 42

On the pulleys

Front 43

What are the extraocular muscle pulleys made of?

Back 43

-Elastin
-Collagen

Front 44

Where are the pulleys in the orbit?

Back 44

In the anterior orbit

Front 45

Which cranial nerves pass through the cavernous sinus?

Back 45

3, 4, V1/2, and VI; and the sympathetic plexus

Front 46

Where does CN III originate?

Back 46

In the midbrain tegmentum

Front 47

What connects the CN III nucleus to the CN VI nucleus?

Back 47

The MLF

Front 48

What happens if a lesion disrupts the communication between CN III and CN IV?

Back 48

INO

Front 49

What 2 vessels does CN III snake between?

Back 49

PCA and Scerebellar A

Front 50

Where is the oculomotor subnucleus for levator palpebrae?

Back 50

In the midline of the oculomotor nucleus

Front 51

What is important to know about the superior rectus subnuclei?

Back 51

They are crossed so innervate the contralateral superior rectus

Front 52

What will happen if we blow out the whole oculomotor nucleus?

Back 52

-Contralateral inability to raise eye
-Bilateral ptosis (low lids)
-Ipsilateral everything else

Front 53

Where is the nucleus for CN IV?

Back 53

In the DORSAL lower midbrain

Front 54

If looking at a cross-section of the lower midbrain, what would you see?

Back 54

-Inferior colliculi (back)
-Sylvian aqueduct (midback)
-Cn IV nuclei
-MLF in front of CN4 nucleus

Front 55

What is the nucleus for CN 3 situated in front of, looking down at a midbrain crosssection?

Back 55

Superior colliculi

Front 56

What cranial nerves pass between PCA and SCA?

Back 56

3 and 4

Front 57

Where is HORIZONTAL GAZE organized?

Back 57

At the pons

Front 58

What neurons help organize horizontal gaze, and where are they housed?

Back 58

-Burst neurons
-Omnipause neurons
Housed in the PPRF

Front 59

What is the PPRF?

Back 59

Peripontine Reticular Formation

Front 60

What cranial nerves are connected to the PPRF?

Back 60

3 and 6

Front 61

How is CN 3 connected to CN 6?

Back 61

Via the MLF

Front 62

What happens to cause horizontal eye movements?

Back 62

1. Omnipause neurons in PPRF turn off
2. Burst neurons excite motor neurons in CN VI nucleus
3. Half these CN VI motor nerves project to contralateral CN III nucleus via MLF
4. Result is both lateral rectus and medial rectus contraction

Front 63

What else gives input to CN VI nucleus?

Back 63

Vestibular nucleus

Front 64

What is achieved by vestibular input to CN VI nucleus?

Back 64

the Vestibuloocular reflex during horizontal head rotations

Front 65

How are the neurons in the PPRF behaving when you AREN'T shifting your gaze?

Back 65

-Omnipause always on and inhibiting the burst neurons.

Front 66

What 2 pieces of info does the MLF carry?

Back 66

-Signals for horizontal gaze from CN 6 to CN 4
-Signals from vestibular nucleus to Interstitial nu of Cajal for vertical gaze

Front 67

What does the rostral interstitial nucleus of the MLF contain?

Back 67

Burst neurons for vertical saccades

Front 68

What is the function of the Interstitial nucleus of Cajal?

Back 68

Vestibular input on vertical ocular motor neurons allows for VERTICAL GAZE HOLDING.

Front 69

What is the Nucleus prepositus hypoglossi for?

Back 69

Horizontal gaze holding

Front 70

What is in the Posterior commisure?

Back 70

Crossing fibers for UPGAZE and pupillomotor structures.

Front 71

So what would result from a unilateral dorsal midbrain lesion or compression of the posterior commissure?

Back 71

Bilateral inability to look up (tectospinal tract)

Front 72

2 sites that give supranuclear control of eye movements:

Back 72

-Cortex
-Vestibular nuclei

Front 73

If you pour cold water in the right ear what happens?

Back 73

The left vestibular nucleus will dominate and make you think you're spinning to the left.

Front 74

What direction will be the
-Slow movement of eyes
-Fast compensatory phase

Back 74

Slow = to the right
Fast = to the left

Front 75

What is this called?

Back 75

Left beating nystagmus

Front 76

What type of nystagmus will result from pouring warm water in the right ear?

Back 76

Right beating nystagmus

Front 77

What does the Frontal Eye field contribute to eye movement?

Back 77

-Voluntary saccades
-Vergence
-Smooth pursuit

Front 78

What does the Supplementary eye field contribute to eye movement?

Back 78

It programs saccades as part of learned or complex behavior.

Front 79

What is the Dorsolateral prefrontal cortex important for in eye movement?

Back 79

Programming saccades to REMEMBERED LOCATIONS

Front 80

What is the Parietal eye field important for in eye movement?

Back 80

Triggering visually guided saccades to reflexively explore the visual environment.

Front 81

What is the Posterior parietal cortex important for in eye movement?

Back 81

Directing visual attention in extrapersonal space

Front 82

What is the MT important for in eye movement?

Back 82

Encoding speed and direction of visual stimuli in 3 dimensions

Front 83

What is the MST important for in eye movement?

Back 83

Encoding moving visual stimuli

Front 84

If you have a right sided stroke on which side would you lose smooth pursuit pathways?

Back 84

On the ipsilateral, same side because the pathway has a double cross.

Front 85

Purpose of eye movements:

Back 85

foeation

Front 86

Horizontal gaze is encoded at the ____ level

Back 86

Pontine

Front 87

Vertical gaze is encoded at the ____ level

Back 87

midbrain

Front 88

The frontal eye field controls:

Back 88

Eye movements in the contralateral direction

Front 89

The MT and MST mediate

Back 89

Pursuit in the ipsilateral direction