Cranial Nerve Examination

Examination

Examination

Introduction

• Introduction, correct patient, consent, wash hands (WINDEC), any pain

• Adequate exposure

• End of the bed inspection

CN I-XII

• CN I - Any change to sense of smell (vanilla essence is rarely used)

• CN II (Eyes)

  • Offer Fundoscopy (shouldn't have to do it)

  • Visual acuity- ask about glassses, offer- Snellen chart + one eye at a time; with glasses on ask to tell the time of the clock (colour- Ishihara plates)

  • Visual fields - both eyes, left & right eye - central & peripheral 

  • Pupillary response to light- direct & indirect, RAPD- pupil dilates with light (CN II, III)

• CN III, IV, VI- eye movements

  • Draw H,

  • Finger-palm: vertical/ horizontal

  • Accommodation response (look into distance then finger close)

• CN V

  • Fine touch V1, V2, V3; (near midline to avoid cervical nerves)

  • Jaw open- don't let me close mouth, masseter muscle

  • Jaw Reflex- abnormal to close, normal: no response

• CN VII

  • Eye brows to ceiling, close eyes (attempt to open)

  • Puff cheeks, show teeth, purse lips (don't let me open mouth)

• CN VIII

  • Hearing b/l- whisper number + rub fingers together & ask to repeat

• CN IX, X

  • Open mouth, say arh- palatal movements; uvula

  • Cough, uvula (X)

  • Swallow (IX, XI, XII)

  • Speech (V, VII, X, XII)

• CN XI

  • Neck rotation + resistance

  • Shrug shoulders + resistance

• CN XII

  • Tongue in mouth + movements

Functions not assessed: 

• Corneal reflex (V, VII)

• Gag reflex (IX, X)

• Sensation to pain and temperature

Conclusion

Thank patient, help to re-dress, wash hands.

Presentation

Structure

• Introduction

• Headline

• Details

• Differentials

• Complications

• Complete assessment

• Investigations

• Management

Examples

1. Confident of MND

I've examined Mr Jones' cranial nerves. My findings are consistent with motor neuron disease. I identified muscle wasting and fasiculations bilaterally and power was reduced throughout the face. Of note there were tongue fasiculations and sensation was normal. My other differentials would be multifocal motor neuropathy and Kennedy's disease. There were no signs of respiratory distress or bulbar involvement, which was reassuring. In order to complete my examination I would like to examine the UL and LL, findings of reduced power with a mixed upper and lower motor neuron distribution without sensory involvement, would support my impression of MND. Investigations

2. Less confident mixed picture

I've examined Mrs Patch's cranial nerves. There was muscle wasting and impairment of cranial nerve 5, 7 and 12 bilaterally.. The cranial nerve 5 signs were a positive jaw reflex and weak masseter muscle. Cranial nerve 7 signs were reduced movements of the face and I was able to open her eyes against resistance. Cranial nerve 12 signs showed weakness of the tongue and I noted tongue fasciculations. There was mixed UMN (the jaw jerk) and LMN (fasciculations) signs present. The differential for these would be MND, B12 subacute degeneration of the combined spinal cord- which usually would have sensory symptoms and syphillis (tabes dorsalis), which has a broad differential.

Physiology

Cranial Nerve Functions

• CN 1- Olfactory: sensory- smell

• CN 2- Optic: Visual acuity (visual fields), pupillary sensory response

• CN 3- Oculomotor: motor eyelids, pupil constriction, eye muscles- inferior oblique; medial, superior and inferior rectus

• CN 4- Trochlear: motor- superior oblique

• CN 5- Trigeminal: sensation of face; motor- mastication & jaw

• CN 6- Abducens: motor- lateral rectus

• CN 7- facial: motor movements of face V1, V2, V3, anterior 2/3rd of tongue

• CN 8- Vestibulo-cochlear: hearing & balance

• CN 9- Glossopharngeal: posterior 1/3rd tongue, swallowing

• CN 10- Vagus: parasympathetic autonomic control of heart, lungs, mouth

• CN 11- accessory: motor- head and shoulder

• CN 12- hypoglossal: motor- tongue, speech

Written in 2026.