Control of Eye Movements Flashcards
Describe the Horizontal Gaze Saccadic System, noting the cranial nerves and tracts involved.
PPRF sends axons to the Abducens nucleus on the ipsilateral side, which will then send axons via the MLF to the CN3 nucleus to and activate the Lateral rectus and medial rectus in opposite eyes.
What structures are involved with the Vertical Saccadic System?
CN 3, CN4 the riMLF, Superior Colliculus
How does the brainstem control saccadic movement?
Saccadic movements need burst neurons to fire, and tonic neurons to for locking onto the target. Pause neurons inhibit burst neurons when locked on so no more movements occur.
Where are Burst Cells located for horizontal gaze control?
PPRF
Where are Burst Cells located for Vertical gaze control?
riMLF
Where are tonic cells located for horizontal gaze control?
Nucleus Prepositus hypoglossi
Where are tonic cells located for vertical gaze control?
Interstitial nucleus of Cajal
where are pause cells located for both horizontal and vertical gaze control?
Omnipause cells of Raphe Nuclei
How do seizures present in terms of lesions?
Seizure are irritating, so yo look away from the lesion.
How do destructive lesion present in terms of eye pathology?
Look toward the trainwreck, so look at the side of lesion.
Describe the path of synapses involved in smooth pursuit.
Parietooccipital junction-> Pontine Nuclei -> Vestibular Nuclei -> Ipsilateral CN6 nuclei -> MLF to Contralateral CN3 Nuclei -> to Lateral rectus and medial rectus muscles in opposite eyes.
Describe the optokinetic system path.
Same as the Smooth pursuit pathway, but adding in nuclei of the accessory optic system.
How will a lesion of the parietal lobe affect the optokinetic system?
Smooth pursuit nystagmus will not occur to the side of the lesion.
How will a left internuclear opthalmoplegia present? (at left MLF)
Left eye cannot adduct.
How will a left CN VI nucleus lesion present?
Left eye cannot abduct, right eye cannot adduct.
