Cranial Nerve

Question 1

CN I

Answer 1

• Olfactory nerve

- Function: Sense of smell

Question 2

CN I test

Answer 2

• Have patient use each nostril separately to smell non-irritating substance (cinnamon, coffee, etc.)
• Often omitted from exam unless frontal lobe damage is suspected or patient says trouble with smell
• Abnormal findings: Anosmia

Question 3

CN II

Answer 3

• Optic nerve

- Function: Vision (fields, acuity), pupillary reflexes

Question 4

CN II test

Answer 4

• Visual field testing - confrontation test; issues = hemianopia, quadrantonopia; visual extinction = visual inattention to one side –> tested with inattention test)
• Visual acuity testing - Snellen chart

Question 5

CN III

Answer 5

• Oculomotor nerve
• Function: Eye movements (medial, superior, inferior rectus & inferior oblique); pupillary construction & accomodation; eyelid opening (levator palpabrae)

Question 6

CN III test

Answer 6

• EOM - ability to move eyes
• Pupillary reflexes - convergence of pupils, re-activity to light
• Eyelid opening - observation of ptosis
• Possible impairments: diploplia, poorly coordinated movements, paralysis, nystagmus, abnormal resting position, ptosis, loss of accommodation, absent/impaired re-activity to light

Question 7

CN IV

Answer 7

• Trochlear Nerve

- Function: Eye movement (superior oblique - depression & adduction)

Question 8

CN IV test

Answer 8

• EOM testing

- Possible Impairments: Diploplia, inability to look down while eye is adducted

Question 9

CN V

Answer 9

• Trigeminal nerve

- Function: Facial sensation, corneal reflex, jaw movements

Question 10

CN V test

Answer 10

• Cranial sensation - cotton swab to face & scalp
• Corneal reflex - cotton swab to cornea
• Jaw movements - palpation of temporalis & masseter + strength testing of jaw opening and closure
• Possible impairments: Decreased sensation, numbness, decreased or absent blink, jaw deviation, weakness of chewing

Question 11

CN VI

Answer 11

• Abducens nerve

- Function: Abduction of eye (lateral rectus)

Question 12

CN VI test

Answer 12

• EOM testing

- Possible impairment: Diploplia with lateral gaze

Question 13

CN VII

Answer 13

• Facial nerve
• Function: Sensation and taste to anterior 2/3 tongue; sensation to external part of ear; facial movement; eyelid closure

Question 14

CN VII test

Answer 14

• Taste - different foods on tongue
• Sensation - cotton swab to ear
• Facial movements - observe symmetry; have patient smile, puff out cheeks, purse lips, wrinkle forehead; raise eyebrows, close eyelids
• Possible impairments: Decreased or absent sensation and taste; Drooping face; Asymmetry of face; Facial weakness or paralysis; Inability to close eyes

Question 15

CN VIII

Answer 15

• Vestibulocochlear nerve

- Function: Cochlear-hearing; vestibular-equilibrium (VOR); gaze fixation

Question 16

CN VIII test

Answer 16

• Auditory - tuning fork, rubbing fingers together, watch
• Vestibular - gaze fixation, balance, analysis of dizziness
• Possible impairments: Diminished/absent hearing or tinnitus; Vertigo; Disequilibrium; Nystagmus; Poor gaze stability with head movements; Positional vertigo and nystagmus

Question 17

CN IX

Answer 17

• Glossopharyngeal Nerve
• Function: Taste & sensation to posterior 1/3 tongue; sensation to pharynx, middle & external ear; elevation of pharynx; parotid gland secretory fibers

Question 18

CN IX test

Answer 18

• Gag reflex - stimulation of pharyngeal wall - look for elevate of palate bilaterally with “ah” noise
• Possible abnormalities: Loss of taste, dry mouth, anesthesia of pharynx; poor gag reflex; diminished or asymmetrical palate elevation (dysphagia, dysphonia, problems with secretions)

Question 19

CN X

Answer 19

• Vagus nerve
• Function: Taste in epiglottis; sensation to epiglottis, larynx, trachea, colon, external ear, etc.; constriction of pharynx, larynx, & palatal muscles; Autonomic (parasympathetic) function to viscera of thorax and abdomen

Question 20

CN X test

Answer 20

• Touch to ear
• Gag reflex
• Exam of soft palate
• Look for signs of autonomic imbalance
• Possible Impairments: Poor or absent gag reflex; persistent horseness; nasal quality to voice; dysphonia; dysphagia; dysarthria

Question 21

CN XI

Answer 21

• Spinal Accessory Nerve

- Function: Head rotation and flexion (SCM); shoulder shrug (trapezius)

Question 22

CN XI test

Answer 22

• Test strength of SCM & upper trapezius

- Possible impairments: weakness of shoulder shrug or head movements

Question 23

CN XII

Answer 23

• Hypoglossal nerve

- Function: Skeletal movement of the tongue

Question 24

CN XII test

Answer 24

• Inspect for asymmetry
• Protrude tongue
• Possible impairment: weakness, wasting of tongue, deviation to ipsilateral side on protrusion, dysphagia