Which nerve innervates the lateral rectus muscle?

• A. Oculomotor nerve (CN III)
• B. Abducens nerve (CN VI)
• C. Trochlear nerve (CN IV)
• D. Facial nerve (CN VII)

Answer: (B)

The lateral rectus moves the eye outward, pulling it away from the midline. This action is carried by the abducens nerve. The abducens nerve originates from the abducens nucleus in the pons and travels to the orbit via the superior orbital fissure to innervate the lateral rectus. In contrast, the oculomotor nerve innervates most of the other extraocular muscles (including the medial rectus), the trochlear nerve supplies the superior oblique, and the facial nerve isn’t involved in eye movements. When the abducens nerve is damaged, the eye can’t abduct properly, leading to horizontal diplopia and an eye that sits deviated medially.