Cranial Nerves and Tests

• Cranial Nerve I: Olfactory


  Responsible for sense of smell.

  Not routinely tested.

  Occlude one nostril and introduce smell. Ask pt to identify. Do both nostrils to test for asymmetry.
• Cranial Nerve II: Optic


  Carries visual information from the retina to the brain.

  Test visual acuity: cover one of patient's eyes + your eye that is opposite to patient, ask patient to follow hand movement and compare to your own visual field.
• Cranial Nerve III: Oculomotor


  Controls eye movements, pupil size, and accommodation.

  Pupil constriction, raised eyelids: Test pupillary reaction to light and ability to open and close eyelids.
• Cranial Nerve IV: trochlear


  Controls eye movement, innervates superior oblique muscle.

  Test movement with pen or finger to all 4 quadrants of sight, including accross the midline.
• Cranial Nerve V: Trigeminal


  3 divisions: opthalmic, maxillary, mandibular.

  Motor: feel masticator muscles (temporal and masseter) while pt clenches jaw. Open jaw against resistance.

  Sensory: with pts eyes closed run cotton swab along forehead, cheeks, and chin on both sides.

  Jaw jerk reflex + corneal reflex (don't perform).
• Cranial Nerve VI: Abducens


  innervates the lateral rectus muscle (abducts eye - looking towards outer corner). Ask pt to move eyes side to side.
• Cranial Nerve VII: Facial

  Motor: smile, furrow brow, puff out cheeks, close eyes - all against resistance.

  Sensory (not routine): give pt a salted or sugar cotton swab and have pt identify - only innervates anterior 2/3 of tongue.
• Cranial Nerve VIII: Vestibulocochlear

  Controls hearing and balance.

  Test hearing acuity by ability to hear normal conversation and by whispered voice test
• Cranial Nerve IX: Glossopharyngeal


  Texted with X.

  Motor - relays information: tongue depresses and ask patient to say "ah". Uvula and soft palate should rise in midline. Tonsils should move medially. Ask to swallow and cough, can test gag reflex.

  Thyroid gland rises when you swallow.

  Sensory: IX controls 1/3 of posterior taste buds, but too difficult to test.
• Cranial Nerve X: Vagus


  Related to autonomic nervous, cardiovascular and respiratory systems.

  Test with IX.

  Depress tongue and say "ah". Ask to swallow and cough, can test gag reflex.

  Thyroid gland rises when you swallow.
• Cranial Nerve XI: Accessory

  Controls head and shoulder muscles.

  Examine sternomastoid/trapezius muscles for symmetry. Ask pt to turn head against resistance, ask pt to shrug shoulders against resistance. Strength should be equal.
• Cranial Nerve XII: Hypoglossal


  Controls tongue.

  Ask pt to stick out tongue, observe for deviation. Can ask pt to say "light, tight, night" make sure language is clear. Inspect for wasting and fasciculation + assess tongue strength using mirror.