Anatomy of the Abducent Nerve — CN VI

1. Big picture

The abducent nerve, also called the abducens nerve or sixth cranial nerve (CN VI), is a small but clinically very important motor cranial nerve. Its job is simple: it innervates the lateral rectus muscle, which abducts the eye, meaning it moves the eye laterally away from the nose.

For the exam, CN VI is important because its lesion gives a very recognizable pattern: horizontal diplopia, worse when looking toward the affected side, with failure of the affected eye to abduct. It is also a classic “false localizing sign” in raised intracranial pressure because of its long intracranial course.