Cranial Nerves Mnemonic
This classic mnemonic helps nursing students remember the 12 cranial nerves in order. Cranial nerve assessment is a fundamental component of the neurological examination and is tested on the NCLEX in questions about stroke assessment, head injury, increased intracranial pressure, and neurological disorders. Knowing the function of each cranial nerve helps you identify deficits and locate the source of neurological dysfunction.
The Mnemonic
"Oh Oh Oh To Touch And Feel Very Good Velvet, AH"
Breakdown
Olfactory (CN I)
Sensory nerve for smell. Test by having the patient identify familiar scents (coffee, vanilla) with eyes closed. Loss of smell (anosmia) can indicate frontal lobe damage, cribriform plate fracture, or upper respiratory infection.
Optic (CN II)
Sensory nerve for vision. Test visual acuity with Snellen chart, visual fields by confrontation, and fundoscopic exam. Papilledema (optic disc swelling) on fundoscopy indicates increased intracranial pressure.
Oculomotor (CN III)
Motor nerve controlling most eye movements, pupil constriction, and eyelid elevation. A blown pupil (fixed, dilated) on one side indicates CN III compression from brain herniation, a neurosurgical emergency.
Trochlear (CN IV)
Motor nerve that controls the superior oblique muscle, allowing downward and inward eye movement. Damage causes difficulty looking down and inward, and the patient may tilt their head to compensate for double vision.
Trigeminal (CN V)
Both sensory (facial sensation) and motor (chewing muscles). Test by touching the face with sharp and dull objects across the three divisions (ophthalmic, maxillary, mandibular). Test motor by having patient clench teeth while palpating masseter muscles. Important for corneal reflex (sensory limb).
Abducens (CN VI)
Motor nerve controlling the lateral rectus muscle (eye abduction, looking outward). Damage causes the affected eye to deviate inward (medial strabismus) and inability to look laterally. Often affected by increased intracranial pressure.
Facial (CN VII)
Mixed nerve: motor for facial expression, sensory for taste on the anterior two-thirds of the tongue. Assess by having patient smile, frown, raise eyebrows, and puff cheeks. Bell's palsy affects this nerve, causing unilateral facial drooping. Important for corneal reflex (motor limb).
Vestibulocochlear (CN VIII)
Sensory nerve for hearing (cochlear branch) and balance (vestibular branch). Test hearing with whisper test or tuning fork (Weber and Rinne tests). Vestibular dysfunction causes vertigo, nystagmus, and balance problems. Ototoxic medications (aminoglycosides, loop diuretics) can damage this nerve.
Glossopharyngeal (CN IX)
Mixed nerve: sensory for taste on posterior one-third of tongue, motor for swallowing. Test gag reflex (sensory limb) and ability to swallow. Assessed together with CN X because they share functions in swallowing and gag reflex.
Vagus (CN X)
Mixed nerve with extensive parasympathetic functions. Controls heart rate, digestion, and voice. Test by listening for hoarseness, checking gag reflex (motor limb), and having patient say 'ah' (uvula should rise midline). Vagal nerve stimulation causes bradycardia.
Accessory (CN XI)
Motor nerve controlling the sternocleidomastoid and trapezius muscles. Test by having patient shrug shoulders against resistance and turn head against resistance. Damage causes shoulder drop and difficulty turning the head.
Hypoglossal (CN XII)
Motor nerve controlling tongue movement. Test by having patient stick out tongue (should protrude midline; deviates toward the side of the lesion). Assess tongue strength by having patient push tongue into cheek against your finger. Important for speech, chewing, and swallowing.
Clinical Relevance
On the NCLEX, cranial nerve questions focus on stroke assessment (facial drooping = CN VII, swallowing difficulty = CN IX/X), increased ICP (blown pupil = CN III, abducens palsy = CN VI), and post-surgical assessment (thyroidectomy = recurrent laryngeal nerve/CN X, assess for hoarseness). Knowing which cranial nerve is affected helps localize the neurological lesion.
Study Tips
- ✓For NCLEX, focus on CN II (vision/papilledema), CN III (pupil changes/ICP), CN VII (facial drooping/stroke), CN IX/X (swallowing/gag reflex), and CN XII (tongue deviation).
- ✓A blown pupil (fixed, dilated) on one side is a late sign of increased ICP and a neurosurgical emergency. This is CN III compression.
- ✓After thyroidectomy, assess for hoarseness (CN X damage to recurrent laryngeal nerve). Have the patient speak to evaluate.
- ✓Cranial nerves are numbered by the order they exit the brainstem, from anterior (I) to posterior (XII).
FAQs
Common questions about this mnemonic
The most commonly tested cranial nerves on the NCLEX are: CN II (Optic) for papilledema and increased ICP assessment; CN III (Oculomotor) for pupil changes indicating herniation; CN VII (Facial) for stroke assessment and Bell's palsy; CN IX and X (Glossopharyngeal and Vagus) for swallowing assessment and aspiration risk; and CN XII (Hypoglossal) for tongue deviation in stroke. Focus your study on these nerves and their clinical assessments.
Dysphagia (difficulty swallowing) involves CN IX (Glossopharyngeal), CN X (Vagus), and CN XII (Hypoglossal). Assess the gag reflex by touching the posterior pharynx with a tongue depressor (CN IX sensory, CN X motor). Have the patient say 'ah' and observe for symmetric uvula rise (CN X). Check tongue movement and strength (CN XII). If any of these assessments are abnormal, the patient is at risk for aspiration and should remain NPO until a formal swallowing evaluation is completed.