The cranial nerve exam is part of the neurological examination. It checks the 12 pairs of cranial nerves that control smell, vision, eye movement, facial sensation and movement, hearing, swallowing, and head and tongue movement.
This guide shows how to test each nerve step by step. It’s written for nursing, medical and PA students and clinicians. Then quiz yourself with the cranial nerve exam practice quiz.
Key takeaways
- Purely sensory nerves: I, II and VIII.
- The pupillary light reflex uses CN II (afferent) and CN III (efferent).
- The corneal reflex uses CN V (afferent) and CN VII (efferent).
- Bell’s palsy (peripheral CN VII) affects the forehead; a stroke usually spares it.
USA Cranial Nerve Exam: Quick Facts
- Number of nerves
- 12 pairs
- Sensory only
- I, II, VIII
- Eye movement
- III, IV, VI
- Gag reflex
- IX (sensory) and X (motor)
- Tongue deviates
- Toward a CN XII lesion
- Uvula deviates
- Away from a CN X lesion
The 12 Cranial Nerves and How to Test Them
| Nerve | Main function | How to test |
|---|---|---|
| I — Olfactory | Smell | Identify a familiar scent in each nostril |
| II — Optic | Vision | Snellen acuity, visual fields, pupillary light reflex |
| III — Oculomotor | Most eye movements, pupil constriction, eyelid elevation | H-pattern eye movements, pupils |
| IV — Trochlear | Superior oblique (look down and in) | H-pattern eye movements |
| V — Trigeminal | Facial sensation, chewing | Light touch on V1–V3, clench jaw, corneal reflex |
| VI — Abducens | Lateral rectus (look outward) | H-pattern eye movements |
| VII — Facial | Facial expression, taste (front 2/3 of tongue) | Raise eyebrows, close eyes tightly, smile, puff cheeks |
| VIII — Vestibulocochlear | Hearing and balance | Whisper test, Weber and Rinne tests |
| IX — Glossopharyngeal | Swallowing, taste (back 1/3), gag sensation | Gag reflex, say “ah” |
| X — Vagus | Palate, pharynx, larynx, organs | Uvula and palate rise, voice, swallowing |
| XI — Accessory | Trapezius and SCM | Shoulder shrug and head turn against resistance |
| XII — Hypoglossal | Tongue movement | Stick out the tongue and move it side to side |
Cranial Nerve Mnemonics
Names (I–XII): “Oh Oh Oh To Touch And Feel Very Good Velvet, Ah Heaven.”
Sensory, motor or both: “Some Say Marry Money But My Brother Says Big Brains Matter More.”
More on Cranial Nerve Mnemonics →Key Reflexes
| Reflex | Afferent (sensory) | Efferent (motor) |
|---|---|---|
| Pupillary light reflex | CN II | CN III |
| Corneal reflex | CN V (V1) | CN VII |
| Gag reflex | CN IX | CN X |
Abnormal Cranial Nerve Findings
- CN III palsy: eye “down and out,” ptosis and a dilated pupil. A compressive cause is an emergency.
- CN IV palsy: trouble looking down and in, such as going down stairs.
- CN VI palsy: can’t move the eye outward, causing double vision on sideways gaze.
- Peripheral CN VII (Bell’s palsy): the whole side of the face is weak, including the forehead.
- Central (UMN) facial weakness, e.g. stroke: the lower face is weak and the forehead is spared.
- CN X lesion: the uvula deviates away from the lesion.
- CN XII lesion: the tongue deviates toward the lesion.
The cranial nerve exam is often documented alongside the mental status exam in a full neuro assessment. Nursing students will see these on the NCLEX.
More on Abnormal Cranial Nerve Findings →Full Neuro Exam
The cranial nerve exam is one part of a full neurological exam:
- Mental status
- Cranial nerves I–XII
- Motor: bulk, tone, strength (0–5)
- Sensory: light touch, pain, vibration, proprioception
- Reflexes (0–4+) and plantar response
- Coordination (finger-to-nose, heel-to-shin) and gait
Free practice test
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Go to the USA Cranial Nerve Exam practice test →USA Cranial Nerve Exam FAQs
How do you test the 12 cranial nerves?
Smell for I; vision and pupils for II; eye movements for III, IV and VI; facial sensation and jaw for V; facial expression for VII; hearing for VIII; gag and palate for IX and X; shoulder shrug for XI; tongue for XII.
Full answer →Which cranial nerves are sensory only?
Cranial nerves I (olfactory), II (optic) and VIII (vestibulocochlear).
Full answer →Which cranial nerve is affected in Bell’s palsy?
The facial nerve, CN VII. Peripheral lesions weaken the entire side of the face, including the forehead.
Full answer →What does the Rinne test check?
It compares air conduction with bone conduction to assess hearing (CN VIII). Normally air conduction is louder than bone conduction.
Full answer →Hypoglossal nerve (CN XII) lesion: which way does the tongue deviate?
Toward the side of the lesion. The weak genioglossus on that side can’t push the tongue forward, so the stronger side pushes it toward the damaged nerve (a lower motor neuron sign).
Full answer →Official sources
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