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Neuro III > Control of Eye Movement > Flashcards

Control of Eye Movement Flashcards

1
Q

Primary gaze

A

Neutral position

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2
Q

Lateral eye moveent

A

Adduction

Abduction

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3
Q

Intorsion

A

Upper eye approaches nose

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4
Q

Extorsion

A

Upper eye approaches temporal region

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5
Q

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

A

Two muscle

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6
Q

Muscle in upward gaze

A

Superior rectus

Inferior oblique

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7
Q

Muscle in downward gaze

A

Inferior rectus

Superior oblique

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8
Q

Cranial Nerves Involved

A

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

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9
Q

CN III: Motor Nerve Fibers

A

Occulomotor nucleus → levator muscles (all except lateral rectus)

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10
Q

CN III: Parasympathetics

A

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

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11
Q

CN III: Where is the Edinger-Westphal Nucleus located

A

In the midline between both occulomotor nuclei

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12
Q

CN III: What is the role of the parasympathetic

A

Round the lens for close focus

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13
Q

CNIII Describe the pupillary light reflex

A

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

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14
Q

CN III: Third Nerve Palsy: 3 signs

A

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

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15
Q

CN IV: Function

A

General somatic efferent innervation to superior oblique

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16
Q

CN IV: Pathway

A

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

17
Q

CN IV: Damage

A
  • Extorsion + medial deviation
  • Inability to depress eye
  • Assume abnormal head position to try and allign the good & bad eye
18
Q

Easily damaged in head trauma

A

CN IV

19
Q

CN VI: Function

A

General soatic efferent innervation to lateral rectus

20
Q

CN VI: Pathway

A

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

21
Q

Tonic activity?

A

Yes, extraoccular motor neurons

22
Q

Define saccade movements

A

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

23
Q

Define microsaccades

A

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

24
Q

Pathway for saccades for horizontal eye movement

A
  1. Cerebral cortex or Superior colliculus

2. Paramerdian pontine reticular formation (PPRF)

25
Q

Pathway for saccades for vertical eyemovement

A
  1. Cerebral cortext or superior colliculs

2. Rostral Interstial Nucleus

26
Q

Supperior Colliculus
Function
Afferent
Efferent

A

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

27
Q

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

A

Visual input is superficial and Motor input is deep

28
Q

What is opthamoplegia?

A

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

29
Q

When do Smooth Persuit Movements occur?

A

Eyes move smoothly when tacking objects or when head is moving

30
Q

What pathway is involved in Smooth Pursuit Movement

A

Vestibulo-ocular Reflex (VOR)

31
Q

What does damage to the VOR cause?

A

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

32
Q

Fixation Reflex

A

Fixate on moving target (Smooth persuit pathway)

33
Q

Optokinetc Reflex

A

Involuntary fixation on objects that are moving relative to the head

34
Q

Convergence or Divergence Reflex

A

Convergence accompanied by pupilary constriction to allow focus on close objects

35
Q

Pupillary Light Reflex

A

Constriction in respose to light

36
Q

Pendular nystagmus

A

Oscillations are equal in both directions

Not CNS or vestibular damage

37
Q

Jerk nystagmus

A

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

38
Q

When is it normal to have nystagmus?

A

End of range of eye movement

Neuro III (8 decks)

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