Facial Nerve (CN VII) Examination: Step-by-Step Clinical Guide

Systematic Facial Nerve Testing

The facial nerve (CN VII) controls facial expression, taste (anterior 2/3 tongue), lacrimation, salivation, and stapedius reflex. Examination follows a rostrocaudal sequence:

1. Inspection at Rest

• Asymmetry: flattened nasolabial fold, lower eyelid laxity, mouth corner droop.
• Fasciculations (lower motor neuron sign).

2. Forehead (Frontalis)

Ask patient to raise eyebrows / wrinkle forehead. LMN lesion: ipsilateral forehead spares? No—LMN paralyzes entire hemiface including forehead. UMN lesion (supranuclear): forehead spared due to bilateral cortical input.

3. Eye Closure (Orbicularis Oculi)

Ask to close eyes tightly. Examiner tries to pry open. Asymmetry = weakness. Test Bell’s phenomenon (upward eye roll on closure attempt).

4. Smile (Zygomaticus Major)

Ask to show teeth / smile broadly. Compare nasolabial fold depth, mouth corner elevation.

5. Cheek Puff (Buccinator)

Ask to puff cheeks; tap gently. Air escapes weak side.

6. Lip Movements

• Purse lips (orbicularis oris) – whistle.
• Say "P, B, M" – tests labial seal.
• Show lower teeth (depressor anguli oris / mentalis).

7. Nasal Wrinkle (Procerus / Nasalis)

Ask to sniff / wrinkle nose.

8. Taste (Chorda Tympani)

Apply sweet/salty/sour/bitter solutions to anterior tongue with cotton swab; patient identifies with eyes closed.

9. Corneal Reflex (Afferent V1, Efferent VII)

Light touch to cornea → bilateral blink. Absent efferent blink = CN VII lesion.

10. Stapedius Reflex (Hyperacusis Screen)

Loud sound → stapedius dampens ossicular chain. Lesion distal to nerve to stapedius → hyperacusis.

Documentation

Grade each branch (House-Brackmann 1–6). Note UMN vs LMN pattern. Correlate with otoscopy (vesicles = Ramsay Hunt), parotid exam, neuroimaging as indicated.