Abducens Nerve Palsy

The sixth cranial nerve, the abducens nerve, is responsible for ipsilateral eye abduction. Dysfunction of the abducens nerve can occur at any point of its transit from the pons to the lateral rectus muscle, resulting in sixth nerve palsy. To understand the causes of abducens nerve palsy, one must have a good grasp of the anatomy of the nerve as it transverses the brain. The abducens nerve begins in the pons near the seventh cranial nerve before exiting the brainstem. At this point, it travels into the subarachnoid space and moves along the skull at the clivus. It then travels to the basal skull at the petrous apex of the temporal bone, where it enters the cavernous sinus. In the cavernous sinus, the internal carotid will be located medially as compared to the abducens nerve. The trigeminal nerve will be found just laterally in the cavernous sinus. The abducens nerve then enters the orbit via the superior orbital fissure and innervates the lateral rectus muscle, resulting in eye abduction.