This schematic provides a lateral view of CNs III, IV, and VI from the brainstem nuclei to the orbit.
The cranial nerve segments within the brainstem are often referred to as being “intramedullary.”
The subarachnoid space lies between the brainstem and cavernous sinus.

• CN III exits the midbrain anteriorly, crosses near the junction of the internal carotid and posterior communicating arteries in the subarachnoid space, and enters the cavernous sinus, where it runs in the lateral wall.
• CN IV exits the midbrain posteriorly and crosses to the opposite side. It then courses through the subarachnoid space and into the cavernous sinus.
• CN VI exits the pons anteriorly, ascends along the clivus, crosses the petrous apex, and passes below the petroclinoid ligament to enter the cavernous sinus, where it runs between the lateral wall and the carotid artery
   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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