Vertical Saccades

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  • Neural pathway that initiates voluntary upward and downward saccades
  • Signal goes to the visual cortex,
    then to the occipital-parietal and frontal gaze centers in both hemispheres;
    from both those cerebral hemisphere gaze centers, the signal goes down to the superior colliculus
    and on to the rostral interstitial nucleus of the MLF (riMLF)
    to initiate vertical saccades; the signal also goes to the interstitial nucleus of Cajal (INC)
    to maintain eccentric gaze
  • Upward saccades
    • Signal goes from the riMLF dorsally through the posterior commissure, ventrally to the superior rectus and inferior oblique subnuclei of the third cranial nerve, and from there to muscles innervated by those nuclei
  • Downward saccades
    • Signal goes through the tegmental midbrain to the superior oblique nucleus and the inferior rectus subnucleus and then to the muscles innervated by those nuclei
  • Bilateral cerebral hemisphere lesions
    • May impair all vertical saccades
    • Spares the vertical vestibulo-ocular reflex (because the vestibulo-ocular pathway is restricted to the brainstem)
    • Tip: impairment of saccades and pursuit with sparing of the vestibulo-ocular reflex is called a “supranuclear gaze palsy”
  • Dorsal (tectal) midbrain lesion
    • May impair upgaze saccades
    • Does not spare the vertical vestibulo-ocular reflex
    • May produce convergence retraction on attempted upgaze
    • May produce upbeat nystagmus on attempted upgaze
  • Ventral (tegmental) midbrain lesion
    • May impair downgaze saccades
    • Does not spare the vertical vestibulo-ocular reflex
    • May impair vertical saccades in one eye as part of a third nerve palsy

Supranuclear Ocular Motor Pathways

Overview Videos Horizontal Saccades Vertical Saccades Pursuit Pathway Vergence Pathway Vestibulo-Ocular Reflex