Control of Eye Movements Flashcards
What is smooth pursuit?
Supranuclear gaze system that keep a moving image centered on the fovea
What is vergence?
Supranuclear gaze control that keeps the image on the fovea when the object is moved near
What system executes voluntary saccadic movement?
Frontal eye fields
What structure do the fibers from the frontal eye fields synapse on to initiate eye movement?
Contralalteral Paramedian Pontine Reticular Formation (PPRF)
Where is the Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus (riMLF) found? What does it control?
Found near superior colliculus and posterior commissure of the brain
Controls vertical gaze
A turmor in what structure can cause vertical gaze palsy? Which direction is the pt unable to look?
Pineal gland
Cannot look up
Lesion to what nucleus can create a palsy where the pt cannot look down?
Lesion to red nucleus
What structure is involved in controlling reflexive saccadic eye movements?
Superior colliculus
What nuclei are the pause cells located in?
Raphe nuclei
What is the function of the burst cells?
Move eyes towards target
What is the function of the tonic cells?
Fix gaze on target
What are the tonic cells for horizontal movement? Where are they located?
Nucleus prepositus hypoglossi
Located in pons
What are the tonic cells for vertical eye movement? Where are they located?
Interstitial nucleus of Cajal
Found in midbrain
What are the burst cells for horizontal eye movement? Vertical eye movement?
Horizontal: Paramedian Pontine Reticular Formation (PPRF)
Vertical: Rostral Interstitial Nucleus of MLF (riMLF)
How would a destructive lesion to the frontal gaze center present?
Eye deviation towards the side of lesion, difficulty looking away
How would seizure activity in the frontal gaze center present?
Eyes deviate away from firing gaze center
What Broadmann area is associated with smooth pursuit?
19 - Parieto-occipital junction
If the right parieto-occipital junction is stimulated, what direction do the eyes move?
To the Right
What is optokinetic nystagmus?
Quick motion in opposite direction when visual target reaches the limit of the visual field
What eye field is required for optokinetic nystagmus?
Intact parietooccipital eye field
Where is the lesion if there is loss of smooth pursuit movements towards the side of the lesion?
Parietal lobe
What is the result of the ice water caloric is the patient is not conscious?
Opposite from COWS
Cold water causes toward nystagmus
Warm water causes away nystagmus
Lesion in what structure causes Intranuclea ophthalmoplegia?
Medial Longitudinal fasciculus
Upon exam, a patient has weak adduction in the left eye, and nystagmus on abduction in the right. Movement to the other side is normal. What is the most likely diagnosis? Where is the lesion?
Left Interocular Ophthalmoplegia
Left MLF
What eye motion remains intact in INO?
Convergence
In a Left CN VI nucleus lesion, what eye movements are inhibited?
Cannot abduct left eye or adduct right eye (Cannot look left)
In a left CN VI palsy, what movements are inhibited?
L eye cannot abduct
Why can convergence still happen if there is a lesion in the MLF?
Near reflex pathway bypasses MLF to get to medial rectus muscles
Argyll-Robertson pupil is a sign of what disease?
Neurosyphilis
What happens in an Argyle-Robertson pupil?
Absent light reflex but pupil constricts in near reflex testing
