If a patient has denervation of the trigeminal nerve (CN V), which deficit would most likely be the result?

• A. Reduced facial expression
• B. Reduced mastication
• C. Reduced tongue mobility
• D. Reduced vocal fold movement

Answer: (B)

Trigeminal nerve supplies motor innervation to the muscles of mastication through its mandibular division. When CN V is denervated, the jaw-closing muscles (masseter, temporalis, and pterygoids) weaken, leading to reduced chewing ability. The other deficits involve different nerves—facial nerve for facial expression, hypoglossal nerve for tongue movements, and vagus nerve for vocal fold movements—so they’re not expected with CN V denervation. Therefore, reduced mastication is the most likely consequence.