Control of Eye Movement

Question 1

Primary gaze

Answer 1

Neutral position

Question 2

Lateral eye moveent

Answer 2

Adduction

Abduction

Question 3

Intorsion

Answer 3

Upper eye approaches nose

Question 4

Extorsion

Answer 4

Upper eye approaches temporal region

Question 5

How many muscles are involved for eye movement above or below the horizontal plane

Answer 5

Two muscle

Question 6

Muscle in upward gaze

Answer 6

Superior rectus

Inferior oblique

Question 7

Muscle in downward gaze

Answer 7

Inferior rectus

Superior oblique

Question 8

Cranial Nerves Involved

Answer 8

CN III - Occulomotor Nerve
CN IV - Trochlear Nerve
CN VI - Abducens Nerve

Question 9

CN III: Motor Nerve Fibers

Answer 9

Occulomotor nucleus → levator muscles (all except lateral rectus)

Question 10

CN III: Parasympathetics

Answer 10

Edinger-Westphal Nucleus → Cillary Ganglion → Constrictor pupilae & ciliary muscle

Question 11

CN III: Where is the Edinger-Westphal Nucleus located

Answer 11

In the midline between both occulomotor nuclei

Question 12

CN III: What is the role of the parasympathetic

Answer 12

Round the lens for close focus

Question 13

CNIII Describe the pupillary light reflex

Answer 13

Afferet nerve fibres → Pretectal nuclei → EWN → cilliary Ganglion → Sphincter pupillae muscle → constrict pupil

Question 14

CN III: Third Nerve Palsy: 3 signs

Answer 14

Ptosis
Diliated pupil
Pupil looks lateral because lateral rectus is innervated by CN VI

Question 15

CN IV: Function

Answer 15

General somatic efferent innervation to superior oblique

Question 16

CN IV: Pathway

Answer 16

CN IV Nucleus → decussation → Exit dorsal brainstem → Cavernous sinus (lateral wall) → Superior oblique muscle

Question 17

CN IV: Damage

Answer 17

• Extorsion + medial deviation
• Inability to depress eye
• Assume abnormal head position to try and allign the good & bad eye

Question 18

Easily damaged in head trauma

Answer 18

CN IV

Question 19

CN VI: Function

Answer 19

General soatic efferent innervation to lateral rectus

Question 20

CN VI: Pathway

Answer 20

CN VI Nucleus (caudal pons) → Exits pontomedullary junction → cavernous sinus (crosses internal carotid) → lateral rectus

Question 21

Tonic activity?

Answer 21

Yes, extraoccular motor neurons

Question 22

Define saccade movements

Answer 22

Voluntary rapid eye movements to allow eyes to keep up with a moving target (3 seconds) followed by head movement

Question 23

Define microsaccades

Answer 23

Small movements that prevent an image from remaining on the same rods & cones (if not, you would lose vision through adaptation)

Question 24

Pathway for saccades for horizontal eye movement

Answer 24

1. Cerebral cortex or Superior colliculus

2. Paramerdian pontine reticular formation (PPRF)

Question 25

Pathway for saccades for vertical eyemovement

Answer 25

1. Cerebral cortext or superior colliculs | 2. Rostral Interstial Nucleus

Question 26

Supperior Colliculus Function Afferent Efferent

Answer 26

Saccadic movements Afferents: Retina, inferior colliculus, spinal cord Efferent: Spinal cord → Tectospinal tract Brain stem → Tectoeticular tract

Question 27

How is the superior colliculus organized what is superficial and what is deep?

Answer 27

Visual input is superficial and Motor input is deep

Question 28

What is opthamoplegia?

Answer 28

Damage to to the MLF transfering information from PPRF to CN VI and CN III nuclei

Question 29

When do Smooth Persuit Movements occur?

Answer 29

Eyes move smoothly when tacking objects or when head is moving

Question 30

What pathway is involved in Smooth Pursuit Movement

Answer 30

Vestibulo-ocular Reflex (VOR)

Question 31

What does damage to the VOR cause?

Answer 31

Drift in eyes as if head was moving → triggers saccadic eye movements to keep eye in focus → Nystagmus

Question 32

Fixation Reflex

Answer 32

Fixate on moving target (Smooth persuit pathway)

Question 33

Optokinetc Reflex

Answer 33

Involuntary fixation on objects that are moving relative to the head

Question 34

Convergence or Divergence Reflex

Answer 34

Convergence accompanied by pupilary constriction to allow focus on close objects

Question 35

Pupillary Light Reflex

Answer 35

Constriction in respose to light

Question 36

Pendular nystagmus

Answer 36

Oscillations are equal in both directions | Not CNS or vestibular damage

Question 37

Jerk nystagmus

Answer 37

Rapid and slow compent Slow: Imbalance in vestibular system, flocculos or MLF Rapid: Compenstatory to try and remain fixated on the object

Question 38

When is it normal to have nystagmus?

Answer 38

End of range of eye movement