DR Medhat MRCP

Supranuclear pathway : extend from cerebral cortex till before brain stem
(i.e before brainstem centers of gaze & motor cranial
nerves nuclei that control eye movement `3,4&6`)
Nuclear pathwaty :
at the level of centers of conjugate gaze in
the reticular formation of brainstem & cranial nerve
nuclei that control eye movement.
Internuclear pathway : parts of reticular formation of brainstem (e.g MLF)
That connect the centers of conjugate movement in
brainstem to the cranial nerve nuclei.
Infra-nuclear pathway : involve the cranial nerves (post nuclei).
• Pathways :
A. Horizontal gaze pathway :
- Supplementary eye field area →frontal eye field (FEF) area 8 in middle frontal gyrus→
contralateral paramedian pontine reticular formation (PPRF)→projections to
ipsilateral 6 th (abducence) cr. nerve nucleus in pons that gives projections to :
→ipsilateral lateral rectus→ipsilateral eye abduction
→contralateral medial longitudinal fasiculous then 3 rd (occulomotor) nerve
nucleus→ contralateral medial rectus→contralateral eye adduction
- Ipsilateral eye abduction + contralateral eye adduction→ conjugate horizontal gaze of
both eyes to the same direction
سبحان هللا وبحمده سبحان هللا الخالق العظيم
B. Vertical gaze pathway :
- There is no single cortical center responsible for vertical gaze.
- Instead, diffuse areas of the cortex project to the rostral interstitial nucleus of the
MLF/Cajal (riMLF) (midbrain center of vertical gaze) →This nucleus projects bilaterally
to the oculomotor and trochlear nuclei, with many of these fibers passing through
the posterior commissar (most dorsal part of midbrain).
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