cranial nerves

Question 1

CN I

Answer 1

Olfactory nerve - We ask about any changes in sense of smell. If there is a change, we ask whether unilateral, bilateral and what change has occurred.

Question 2

CN II

Answer 2

Optic nerve = Vision

Tests = Visual acuity, pupillary response, visual builds, visual inattention, accommodation and fundoscopy.

Question 3

Visual acuity

Answer 3

The ability of the eye to adapt to produce a clear focused image by alternating the curvature of the lens.

Test = Snellin chart. One eye covered read as many letters as possible at 6 metres.

Question 4

Pupillary response

Answer 4

1) Shine within eye, direct.
- You expect constriction on the pupil (Afferent CN II)

2) Contralateral eye, Consenual response.
- You still expect constriction (of both eyes)

Finally swinging light test (May reveal Marcus Gunn)

Efferent = CNIII

Question 5

Visual fields

Answer 5

1) Sit 1 metre from the patient
2) Ask patient to cover eye, you cover the opposite eye (there right and your left eye)
3) Bring finger from the furthest periphery towards centre vision
4) Patient says yes once they can see it
5) Repeat in all 4 quadrants

Question 6

Accommodation

Answer 6

Constriction + convergence when looking at the wall behind and then at pen close

Question 7

Colour vision

Answer 7

Ishihara chart

Question 8

Visual inattention

Answer 8

Put hands high and wide, whilst patient looks directly at you they have to recognise which side the finger moves.

Once it is established they can see both, move both fingers at the same time.

Repeat low and wide

Question 9

CN III

Answer 9

Occulomotor = Innervation of the superior, medial and inferior rectus muscles, inferior oblique and levator palpebral superiors muscle (Eyelid).

Also parasympathetic of constrictor pupillae (Pupil size) and ciliary muscle (Accommodation)

Look for signs of ptosis (Drooping eyelid) or abnormal gaze

Question 10

CN IV

Answer 10

Trochlear nerve = Innervates the superior oblique muscle

Question 11

CN VI

Answer 11

Abducent nerve = Innervates the lateral rectus muscle

Question 12

Eye movement (CN III, IV and VI)

Answer 12

1) Ask patient to keep their head still

2) Ask patient to follow your finger (Only eyes, they shouldn’t move their head) as you make a H shape slowly

Question 13

CN V

Answer 13

Trigeminal nerve = Supplies sensation to the face and motor function to muscle of mastication

Question 14

How to test CN V1?

Answer 14

Eyes closes recognise cotton wool on forehead (Opthalmic division) repeat with neurotip

Corneal reflex, Afferent V1 = Ask to look up to the left and touch the cornea of the right eye with a wisp of cotton wool, repeat on the other eye

Question 15

How to test CN V2?

Answer 15

Eyes closes recognise cotton wool on cheek (Maxillary division) repeat with neurotip

Question 16

How to test CN V3?

Answer 16

Eyes closes recognise cotton wool on jaw (Mandibular division) repeat with neurotip

Test motor function by palpating the massetor as they clench their jaw

Jaw jerk test = Finger on mandible as mouth is open and strike with a tendon hammer. should be little to no response, exaggerated response indicates an UMN lesion.

Question 17

Corneal reflex

Answer 17

Corneal reflex, Afferent V1, efferent VII = Ask to look up to the left and touch the cornea of the right eye with a wisp of cotton wool, repeat on the other eye

Question 18

Jaw-jerk test

Answer 18

Jaw jerk test = Finger on mandible as mouth is open and strike with a tendon hammer. should be little to no response, exaggerated response indicates an UMN lesion.

Afferent = V3, Efferent = V3

Question 19

CN VII

Answer 19

Facial nerve =

• Supplies muscle of fascial expression
• Taste to the anterior 2/3rd of the tongue
• Secretomotor to submandibular and sublingual glands

Question 20

Testing CN VII

Answer 20

Inspection = Symmetry?

Motor = 1) Wrinkle forehead

2) Screw up their eyes
3) Smile/show teeth

Sensation = Ask about changes in taste

Question 21

CN VIII

Answer 21

Vestibulocochlear = Equilibrium/balance and hearing

Question 22

Testing CN VIII

Answer 22

Vestibular = Check nystagmus (Often done when testing eye movement). Check balance (Often done with gait)

Hearing = Whisper test
Tuning fork test = Rinne’s and Webber’s

Question 23

CN IX

Answer 23

Glossopharyngeal = Sensation to the pharynx and tonsils. Sensation and taste to the posterior 2/3rds of the tongue. Innervates stylopharyngeus muscle.

Question 24

CN X

Answer 24

Vagus = Many, including sensation and innervation to palatine, pharyngeal and laryngeal muscles

Question 25

Testing CN IX and X

Answer 25

Glossopharyngeal and Vagus
1) Inspection = Open mouth and say “ahhh” Palate elevates symmetrically and no deviation of the uvula.

2) Cough = Sound normal?
3) Gag reflex = Touch side of the throat (Afferent IX and efferent X)

Question 26

XI

Answer 26

Accessory nerve = Innervates the upper trapezius and sternocleidomastoid

Question 27

XI - Trapezius

Answer 27

Place you hands on the patients shoulders and ask them to shrug

Question 28

XI - Sternocleidomastoid

Answer 28

Ask the patient to turn their head to either side and visualise the muscle contraction.

Then ask them to push against as you place your fist on the side of their face.

Question 29

CN XII

Answer 29

Hypoglossal nerve = Innervates the tongue

Question 30

Testing CN XII

Answer 30

Inspection = Look at tongue, fasciculations? Wasting? Deviation?

Motor = Ask patient to stick tongue out and then move side to side

Speech