Which cranial nerve has functions including both eye movement and jaw movement?

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

Answer: (B)

Eye movement is controlled by three nerves that move the eye itself (the oculomotor, trochlear, and abducens nerves). Jaw movement, on the other hand, comes from the trigeminal nerve, specifically its mandibular division, which innervates the muscles of mastication such as the masseter, temporalis, and pterygoids. Among the options given, the trigeminal nerve is the one that includes a motor component for jaw movement, while the other nerves listed do not. This is why it’s the best choice when the question asks about a nerve associated with jaw movement. Note that true eye movement is not a function of the trigeminal nerve, which is why the other nerves are not correct for the jaw-movement aspect.