Abducent Nerve (CN VI)

Functions: Somatic motor (general somatic efferent) to one extra-ocular muscle, the lateral rectus.

Nucleus: The abducent nucleus is in the pons near the median plane.

The abducent nerve (CN VI) emerges from the brainstem between the pons and the medulla and traverses the pontine cistern of the subarachnoid space, the right and left nerves straddling the basilar artery. Each abducent nerve then pierces the dura to run the longest intradural course within the cranial cavity of all the cranial nerves - that is, its point of entry into the dura mater covering the clivus is the most distant from its exit from the cranium via the superior orbital fissure. During its intradural course, it bends sharply over the crest of the petrous part of the temporal bone and then courses through the cavernous sinus, surrounded by the venous blood in the same manner as the internal carotid artery, which it parallels in the sinus. CN VI traverses the common tendinous ring (Latin anulus tendineus communis) as it enters the orbit, running on and penetrating the medial surface of the lateral rectus, which abducts the pupil.