A patient has facial droop but is still able to close the eye on the affected side. Which cranial nerve is involved?

Correct answer: B. Facial nerve (CN VII)

• A. Incorrect. CN III controls extraocular movement and the levator palpebrae (eyelid ELEVATION), not facial expression.
• B. Correct. Facial weakness of any origin is CN VII. Preserved eye closure indicates a CENTRAL (upper motor neuron) lesion — the forehead and orbicularis oculi receive bilateral cortical input and are therefore spared.
• C. Incorrect. CN V provides facial SENSATION and motor supply to the muscles of mastication, not facial expression.
• D. Incorrect. CN IX supplies the stylopharyngeus, posterior tongue taste and pharyngeal sensation.

Note: 📌 Critical distinction: FOREHEAD SPARED (can close eye, can wrinkle forehead) = CENTRAL/UMN lesion — think stroke, urgent referral. FOREHEAD INVOLVED (cannot close eye) = PERIPHERAL/LMN lesion — Bell's palsy or Ramsay Hunt.