Question #525
Considering the abducent nerve
The abducent nerve is the sixth cranial nerve. It arises from the brainstem once the facial nerve fibres have wrapped around its nucleus. The nerve traverses up through the pontine cistern and bends over the crest of the petrous part of the temporal bone to enter the cavernous sinus. In the cavernous sinus the nerve passes inferior to the carotid artery. On leaving the cavernous sinus the nerve enters the orbit through the superior orbital fissure and then the tendinous ring to supply lateral rectus (a muscle with two belles that fuse prior to inserting into the eyeball).
The pontine cistern is a subarachnoid space filled with CSF. The abducent nerve therefore has the longest subarachnoid intracranial course of all the cranial nerves. The trochlear nerve has the longest intracranial course overall.
