Neuroanatomy
Supranuclear Gaze Pathways
Saccades (fast eye movements) originate from the frontal eye fields in area 8 of the frontal lobes and the superior colliculus
Pathway
- Fibres pass from the FEFs
- Through the anterior limb of the internal capsule
- Through the thalamus
- Decussate in the lower midbrain
Terminate in the contralateral PPRF
Connections
- Vestibular nuclei connect with the contralateral PPRF
- Signals from the right horizontal canal transmit to the left PPRF
The pontine paramedial reticular formation (horizontal gaze centre) extends from the trochlear to the abducens (VI nerve) nucleus
- Starting point for all conjugate horizontal eye movements
- Connects ipsilateral abducens nucleus
Contains one type of neurone to the ipsilateral lateral rectus
Another type travels in the MLF to the medial rectus of the contralateral oculomotor nucleus.
Hot Topic
Together the PPRF and MLF facilitate simultaneous contraction of lateral rectus and contralateral medial rectus
- There is no definite vertical gaze centre
- Supranuclear control of vertical eye movements arise in the FEFs or superior colliculus
These input to the rostral interstitial nucleus of the MLF and the third and fourth nerve nuclei.
- The interstitial nucleus of Cajal is involved with vertical pursuits