Cranial Nerve Exam

 

The cranial nerves leave the brainstem to innervate the head and neck, providing many insights into brainstem functioning. They are easily accessible, and can be quickly tested.

U of T has made some great cranial nerve exam videos.

 

 

Cranial Nerve

testing

abnormalities

I (olfactory)

smell: coffee, vinegar, peppermint

unilateral loss suggests frontal lobe lesion

II (optic)
  • visual acuity (Snellen eye chart)
  • pupillary reflex (afferent)
  • visual fields
  • direct and consensual constriction
  • swinging flashlight test to look for RAPD
  • accomodation: constriction when focussed on a near object
  • blind spot
  • fundoscopy
  • optic discs can demonstrate edema or optic atrophy

III, IV, VI
  • eye movements
  • pupillary reflex (CN III efferent)
  • ptosis/ eye down and out: CN III
  • head tilted, vertical diplopia: CN IV
  • crossed eyes; impared lateral gaze: CN VI

V (trigeminal)
  • light touch, pain, and temp over VI, II, III
  • muscles of mastication
  • jaw reflex
  • corneal reflex (afferent)

 

VII (facial)
  • muscles of facial expression: eyebrows, closed eyes, puffed cheeks, bared teeth
  • "Pa, Pa, Pa"
  • sensation around ear canal
  • taste anterior 2/3 of tongue
  • corneal reflex (efferent)
  • forehead sparing = upper motor lesion
  • parasympathetic disruption leads to loss of salivation/lacrimation

VIII
  • hearing
  • check for nystagmus
  • Dix-Hall-Pike maneuver
  

IX, X
  • sensation of palate
  • taste posterior 1/3 (IX)
  • uvula and palate movement (X)
  • gag reflex
  • "Ka, Ka, Ka"
  • coughing, swallowing
  • dysarthria

XI
  • trapezius: shoulder shrug
  • SCM, head turn

 

XII
  • tongue stuck out
  • "La, La, La"
  • tongue points to the affected side