Cranial Nerves

Question 1

CN I

Answer 1

• Olfactory
• Function: sensory, sense of smell
• Test: smell easily identifiable objects one nostril at a time

Question 2

CN II

Answer 2

• Optic
• Function: vision, sensory
• Test: direct and consensual pupil rxn, PERRLA assessment

Question 3

CN III

Answer 3

• Oculomotor
• Function: eye movement, pupil constriction, eyelid control, motor
• Test: EOMs & PERRLA assessment

Question 4

CN IV

Answer 4

• Trochlear
• Function: downward and inward eye movement, motor
• Test: EOMs assessment

Question 5

CN V

Answer 5

• Trigeminal
• Function: innervates all regions of face, divided into 3 regions
• Test: sharp/dull object on cheek bones, hands on sides of face and moving mouth around, corneal reflexes

Question 6

CN VI

Answer 6

• Abducens
• Function: lateral eye movement, motor
• Test: EOMs assessment

Question 7

CN VII

Answer 7

• Facial
• Function: facial expression, motor, taste (anterior ⅔ of tongue), sensory
• Test: symmetrical during smile, raise eyebrow, open/close eyes, puff cheeks, speaking + assessing taste by applying sweet/salty to anterior tongue portion

Question 8

CN VIII

Answer 8

• Acoustic / Vestibulocochlear
• Function: hearing and equilibrium
• Test:
  
  • Rinne Test: compares air conduction to bone (norm 2:1)
  • Weber’s test: assess lateralization of sound to unaffected ear
  • Whisper test
  • Gait and balance observation

Question 9

CN IX

Answer 9

• Glossopharyngeal
• Function: taste on posterior ⅓ of tongue (bitter/sour), gag reflex, sensation of nasopharynx, sensory, swallowing, phonation, secretion of salivary glands and carotid reflex, PNS
• Test: evoke gag reflex, look for symmetry of uvula and tongue + for taste apply sour/bitter to posterior ⅓ of tongue

Question 10

CN X

Answer 10

• Vagus
• Function: muscles of guttural speech and swallowing, sensation of external ear canal, posterior auricular area, secretion of digestive enzymes/peristalsis/carotid reflex, involuntary movement of heart/lungs/GI tract, PNS
• Test: say “ahhhh”

Question 11

CN XI

Answer 11

• Accessory (Spinal Accessory)
• Function: provides motor innervation to sternocleidomastoid and trapezius muscles
• Test: shrugging shoulders w/ opposing pressure, ROM & strength of neck

Question 12

CN XII

Answer 12

• Hypoglossal
• Function: tongue movement for articulation and swallowing
• Test: stick tongue out and move it left, right, up, down + listen to speech + look for symmetry