The abducens nerve or abducent nerve (the sixth cranial nerve, also called the sixth nerve or simply VI) is a “somatic efferent” nerve that controls the movement of a single muscle, the lateral rectus muscle of the eye, in humans. In most other mammals it also innervates the musculus retractor bulbi, that can retract the eye for protection. Homologous abducens nerves are found in all vertebrates except lampreys and hagfishes. The human CN VI is derived from the basal plate of the embryonic pons.