Anatomy & Histology · patient case question
Which nerve is involved?
Patient case: Facial droop with preserved eye closure
Scenario: A patient whose face DROOPS but who CAN still close the eye.
Show answer and explanation
Correct answer: A. Cranial nerve VII (facial)
- A. Correct. The FACIAL NERVE (CN VII) supplies all the muscles of facial expression; weakness of these muscles produces the facial droop.
- B. The trigeminal nerve (CN V) is primarily SENSORY to the face and supplies the muscles of MASTICATION — not facial expression. Its lesions cause facial numbness or jaw weakness, not droop.
- C. CN IX supplies taste and sensation to the posterior third of the tongue and motor supply to stylopharyngeus.
- D. CN III controls most extraocular movement and the levator palpebrae; its palsy causes ptosis and a 'down-and-out' eye, not a drooping cheek and mouth.
Note: ⚠️ IMPORTANT NUANCE. PRESERVED eye closure with lower-face droop points to an UPPER MOTOR NEURON (central) lesion — a stroke — because the forehead and orbicularis oculi receive BILATERAL cortical input. A LOWER motor neuron lesion (Bell's palsy, Ramsay Hunt) paralyses the WHOLE side including eye closure. The exam intended CN VII, but this distinction is high-yield and could be the point of the question.
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