M2-C2-L30 --> Eye Movements

Front 1

Visual input from each eye is transmitted independently through the __________ to the __________, where vision is perceived.

Back 1

Lateral Geniculate Nucleus

Ocular Dominance Columns in Area 17

Front 2

What muscles cause adduction of eye?

Back 2

Middle Rectus
Superior Rectus
Inferior Rectus

Front 3

What muscles cause abduction of eye?

Back 3

Lateral Rectus
Superior Oblique
Inferior Oblique

Front 4

What muscles cause elevation of eye?

Back 4

Superior rectus
Inferior oblique

Front 5

What muscles cause depression of eye?

Back 5

Superior oblique
Inferior rectus

Front 6

What muscles cause intorsion of eye?

Back 6

Superior rectus
Superior oblique

Front 7

What muscles cause extorsion of eye?

Back 7

Inferior rectus
Inferior oblique

Front 8

Abducting eyes will allow isolation of what muscles?

Back 8

Superior Rectus
Inferior Rectus

Front 9

Adducting eyes will allow isolation of what muscles?

Back 9

Superior Oblique
Inferior Oblique

Front 10

T/F - Corticobulbar fibers are directly received by the Occulomotor system (CN III, IV, VI)

Back 10

False.

Though most CN's motor nuclei are excited by corticobulbar fibers (allowing for coritcal control), these are not.

Front 11

For control of eye movements, where must the corticobulbar fibers project to?

Back 11

Brainstem centers in the Reticular Formation

Front 12

Define Gaze Center

Back 12

Areas of Reticular Formation that program eye movements.

Front 13

Where is the lateral gaze center (or PPRF or parabducens) located?

Back 13

In RF at level of facial colliculus.

Front 14

Where does the lateral gaze center (or PPRF or parabducens) project to in terms of muscle nuclei?

Back 14

Ipsilateral abducens nucleus

Contralateral occulomotor nucleus

Front 15

Describe the pathway for the lateral gaze center (PPRF or parabducens) to reach the eye muscles.

Back 15

The center projects to the ipsilateral lateral rectus muscle. It also sends projections which decussates via MLF (medial longitudinal fasciculus) to the contralateral medial rectus muscles.

Front 16

Where is the vertical gaze center (aka rostral intersitial nucleus of the MLF) located?

Back 16

In RF at the level of superior colliculi.

Front 17

Where does the vertical gaze center (aka rostral interstitial nucleus of the MLF) project to in terms of muscle nuclei?

Back 17

Oculomotor nuclei

Trochlear nuclei

Front 18

What brainstem center is responsible for convergence and divergence?

Back 18

Perlia's nucleus

Front 19

Perlia's nucleus is part of what complex?

Back 19

Oculomotor complex

Front 20

T/F - Perlia's nucleus utilizes the Medial Longitudinal Fasciculus in vergence movements.

Back 20

False.

Front 21

What are the two cells that brainstems of eye movements contain?

Back 21

Burst cells

Tonic cells

Front 22

Describe burst cells.

Back 22

Extremely rapid firing cells that mediate saccadic (rapid) eye movements

Front 23

Describe tonic cells.

Back 23

Slower firing than burst cells that mediate slow movements

Front 24

When eyes are stationary, describe the firing of burst and tonic cells.

Back 24

Fire with constant rate

Front 25

What does the nucleus prepositus hypoglossi do?

Back 25

Integrate signals of saccadic eye movements to derive a new position signal for tonic cells.

Front 26

What does the Oculomotor channel through the basal ganglia do?

Back 26

Facilitate or suppress eye movements.

Front 27

Where are GABA neurons located and what do they do?

Back 27

In the Substantia Nigra pars reticulata

Exert inhibitory effect on eye movements, which ceases firing during saccades.

Front 28

Where do the GABA neurons project to?

Back 28

VA & VL Thalamus

Superior Colliculus

Front 29

Basal Ganglia diseases can produce what symptoms?

Back 29

Abnormal eye movement or eye fixation

Front 30

List two Cerebral Cortical areas influencing eye movement.

Back 30

Frontal Eye fields

Visual Association Cortex

Front 31

Where are the Frontal Eye Fields located?

Back 31

Brodmann's area 8 in the Middle Frontal Gyrus

Front 32

What does the Frontal Eye Field do?

Back 32

Directs Voluntary rotation of both eyes to contralateral side.

These are for saccadic eye movements

Front 33

The Frontal Eye field receives input from where?

Back 33

Visual Cortex

Front 34

The Frontal Eye Field projects to where?

Back 34

Contralateral Lateral Gaze Center

Vertical Gaze Center

Ipsilateral Superior Colliculus

Front 35

Where is the visual association cortex located?

Back 35

Brodmann's 18 & 19

Temporal Areas

Parietal Areas

Front 36

Where does the visual association cortex receive input from?

Back 36

Primary visual cortex

Front 37

Where does the visual association cortex project to?

Back 37

Contralateral Lateral Gaze Center

Vertical Gaze Center

Ipsilateral Superior colliculus

Front 38

What does the visual association center do?

Back 38

Directs smooth pursuit (tracking) movements mainly to ipsilateral side.

Front 39

What are the two type of eye movements?

Back 39

Conjugate and dysconjugate

Front 40

What are the four types of conjugate eye movements?

Back 40

1. Volunteer
2. Smooth pursuit (tracking)
3. Vestibulo-ocular reflex
4. Visual, Auditory, and Somatosensory reflex

Front 41

Describe the movement character of voluntary eye movement, and state the involvement of each cell type.

Back 41

Saccadic

Rapid jerks mediated by burst cells

Holding each eye in new position mediated by tonic cells

Front 42

The voluntary eye movement is directed by what?

Back 42

Frontal Eye Fields,

each moving eyes to the contralateral side.

Front 43

Explain the effect of visual input in voluntary eye movements.

Back 43

Can be utilized or overridden

Front 44

Smooth pursuit (tracking) movements are mediated by what circuit?

Back 44

Cortical reflex circuit.

Front 45

What are the components of the cortical reflex circuit?

Back 45

Visual association cortex

Temporal area

Parietal area

Front 46

For smooth pursuit (tracking) movements of the eye, what signals are integrated?

Back 46

Visual Association Cortex signal

Vestibular signal

Flocculonodular (cerebellar) signal.

Front 47

The optokinetic reflex is induced how?

Back 47

By movement of the whole visual field across retina (retinal slip)

Front 48

Failure to elicit an optokinetic reflex may suggest what lesions?

Back 48

Cortical lesion in areas 18, 19, temporal region, and parietal region.

Front 49

What is an optokinetic reflex?

Back 49

Ability to follow object across retinal field without moving head, then quickly "snap back" to another object in motion.

Front 50

What is vestibulo-occular reflex?

Back 50

Ability to move eyes opposite to head movement.

Thus eyes can remain fixed on object while head is moving

Front 51

The vestibulo-ocular reflex results from stimulation of what?

Back 51

Semicircular ducts

Front 52

Clinically, the Vestibulo-ocular reflex is used to evaluate what in what type of patients.

Back 52

Brainstem injury in unconscious patients.

Front 53

Why would a unilateral legion cause vestibular nystagmus?

Back 53

Since each gaze center receives BILATERAL, tonic input; a unilateral legion would cause an inbalance affecting the vestibulo-ocular reflex.

Front 54

The visual, auditory, and somatosensory reflex have what kind of eye movements?

Back 54

Saccadic

Front 55

The visual, auditory, & somatosensory reflex involves what type of reflex circuit?

Back 55

Strictly a subcortical (brainstem) reflex circuit.

Thus does not involve the cortex

Front 56

The accomodation-convergence reflex is good for what?

Back 56

Near vision

Front 57

What happens in accomodation-convergence reflex?

Back 57

Convergence - eyes rotate medially.

Accomodation - eyes focus for near vision

Miosis - pupils constrict for increased depth of focus

Front 58

Each component of the accomodation-convergence reflex is mediated by what nerve?

Back 58

Occulomotor nerve

Front 59

What are the symptoms associated with a lesion on the oculomotor nerve? x4

Back 59

1. External Strasbismus (exotropia) and Diplopia

2. Ptosis (more so than Horner's)

3. Midriasis (and loss of pupilary light reflex)

4. Loss of accomodation-convergence reflex

Front 60

What are the symptoms of a lesion on the superior division of the oculomotor nerve?

Back 60

Double elevator palsy

Front 61

What are the symptoms associated with trochlear nerve lesions? x3

Back 61

1. Hypertropia

2. Extortion

3. Vertical diplopia

Front 62

What are the symptoms associated with abducens nerve lesions? x2

Back 62

Internal Strabismus

Diplopia

Front 63

What are the symptoms associated with lesion on abducens nuclei? x2

Back 63

Same as lesion on abducens nerve PLUS lateral gaze paralysis

Front 64

A lesion of the MLF would manifest what symptoms? x3

Back 64

1. Internuclear ophthalmoplegia

2. No voluntary adduction

3. Nystagmus in the abducting eye.

Front 65

Parinaud's syndrome would indicate a lesion where?

Back 65

Midbrain Reticular Formation

Front 66

Parinaud's syndrome would manifest what symptoms?

Back 66

1. Paralysis of upward gaze

2. Mydriasis (and loss of pupillary light reflex)

3. Inpaired convergence

Front 67

An irritative lesion of the frontal eye fields would manifest as what symptom?

Back 67

Deviation of the eye to opposite side.

Front 68

A destructive lesion of the frontal eye field would manifest as what symptom?

Back 68

Deviation of the eye to side of lesion

Inability to gaze to opposite size

Front 69

A lesion of the visual association cortex would manifest as what?

Back 69

Defective tracking and convergence.

Front 70

A vestibular nuclei lesion would manifest as what?

Back 70

Nystagmus

Front 71

A flocculonodular lobe lesion would manifest as what?

Back 71

Nystagmus