Ocular Motility Flashcards
T or F:
Neurological pathways governing ocular motility are independent of vision
TRUE
CN III control what extraocular muscles?
Superior, inferior and medial recti, inferior oblique
CN IV controls what extraocular muscle?
Superior oblique
CN VI controls what extraocular muscle?
Lateral rectus
Primary Action of Medial rectus
Adducts
Primary Action of Lateral rectus
Abducts
Primary Action of Superior rectus
Elevates
Primary Action of Infereior rectus
Depresses
Primary Action of Superior oblique
Depresses
Primary Action of Inferior oblique
Elevates
Neural mechanisms that govern eye movements reside mainly in the
Midbrain and Pons
Symmetrical and synchronous movement of the eyes
Conjugate movement of the the eyes
Simultaneous movement of the eyes in the opposite direction
Disconjugate or disjunctive
Rapid movements of the eyes that serve to fixate on a target
Saccades
Following movements of the eyes when they are fixated on a moving
target
Smooth pursuit
Disconjugate eye movements which serve to maintain binocular single vision
and depth perception
Vergence
Maintains the eyes on a target by constant tonic contraction of the extraocular
muscles (gaze holding)
Fixation
If a series of visual targets enters the visual field, as when one is
watching trees from a moving car, ot the stripes of a rotating drum, repeated quick saccades
refocus the eyes centrally; the resulting repeated cycles of pursuit and refixation are termed
optokinetic nystagmus
Means of this reflex, a movement of the eyes is produced that is
equal and opposite to movement of the head
Vestibulo-ocular reflex
Controls horizontal saccades to the opposite side
frontal eye fields (FEF)
All the pathways mediating saccadic and pursuit movements in the horizontal plane
as well as vestibular and optokinetic movements converge on
pontine centers for horizontal gaze
Generally under BILATERAL control of the cerebral cortex and the upper brainstem, govern upward and downward gaze are situated in the pretectal areas of the midbrain
vertical eye movements
Any lesion which can affect the frontal eye fields and the pathway down to
the PPRF
Central Disorders
Supranuclear
Lesion between between the PPRF and cranial nerve nuclei
Central Disorders
Internuclear
Contralateral (with respect to the PPRF) medial rectus does not receive a signal to contract
Labeled by the side with adduction failure
Internuclear Opthalmoplegia (INO) or Medial Longitudinal Fasciculus Syndrome
conjugate gaze palsy to one side (“one”) and
impaired adduction on looking to the other side (“and a half”)
“The one and half syndrome”
Usually results from a mass lesion involving the region of the posterior third ventricle and upper
dorsal midbrain
Parinaud Syndrome
Also known as Sylvian aqueduct syndrome, dorsal midbrain syndrome, or the syndrome of the posterior commissure.
Parinaud Syndrome
