Session 8 - Oculomotor, Trigeminal And Facial Nerve

Question 1

What symptoms would you see in a palsy of the oculomotor nerve proper?

Answer 1

Eye would be in a down and out position

Complete ptosis

Question 2

What is the oculomotor nerve ‘proper’

Answer 2

Somatic element of the nerve only

Does not contain the sympathetic fibres

Question 3

Why do you get pupil dilation if there is palsy of the oculomotor nerve?

Answer 3

Oculomotor nerve has parasympathetic efferents to the sphincter pupillae. If this is knocked out then you get unopposed action of dilator pupillae and therefore pupil dilation.

Question 4

What is the origin of the oculomotor nerve and from where does it exit the cranium?

Answer 4

From the oculomotor nucleus

Leaves via superior orbital fissure

Question 5

What is the site of origin of the parasympathetic nerves that hitch-hike the oculomotor nerve?

Answer 5

Edinger-Westphal nucleus - midbrain

Question 6

What muscles does the oculomotor nerve supply?

Answer 6

Inferior oblique 
Superior rectus 
Inferior rectus 
Medial rectus 
Levator palpebrae superioris

Question 7

Where would the lesion be if there was only a palsy of the oculomotor nerve proper?

Answer 7

Distal to ciliary ganglion

E.g. Pupil sparing third palsy

Question 8

What are the branches of the trigeminal nerve?

Answer 8

Opthalmic
Maxillary
Mandibular

Question 9

What nerve is affected in Harlequin syndrome?

Answer 9

CNV

Question 10

What are the symptoms of harlequin syndrome?

Answer 10

Affects Ipsilateral side
Loss of sensation to 1/2 face
Anhydrosis
Vasomotor dysfunction

Question 11

What is the origin of the facial nerve?

Answer 11

Facial motor nucleus - pons
Nucleus solitarius - sensory afferents
Superior salivatory nucleus - visceral afferents

Question 12

What are the targets of the nucleus solitarius?

Answer 12

Supplies visceral afferents:
Lacrimal gland 
Sublingual gland 
Submandibular glands 
Nasal glands 
Palatine glands 
Special sensory 
Anterior 2/3rds tongue taste - chordi tympani 
General sensory - auricle of ear

Question 13

What are the branches of the facial nerve? (E.g motor component)
Ipsilateral

Answer 13

Temporal 
Zygomatic 
Buccal
Mandibular 
Cervical

Question 14

Describe the origin and course of the facial nerve (motor)?

Answer 14

Facial motor nucleus
Exits cranium via the stylomastoid foramen
Then enters the parotid gland where it forms the parotid plexus and gives off it’s branches.

Question 15

Give examples of when the facial nerve can be damaged:

Answer 15

Parotidectomy
Forceps delivery of baby
Tumours of parotid gland
Parotitis

Question 16

What are the clinical signs of complete CNVII nerve palsy?

Answer 16

Usually permanent
Loss of facial expression - facial asymmetry
Loss of lacrimation
Loss of salivation
Loss of secretomotor function to nasal and oral mucous membrane.
Hyperacusis - loss of nerve to stapedius
Loss of action of sphincter muscles:
Orbicularis oculi - cannot close eyes
Orbicularis oris - cannot close mouth - drooling

Question 17

How could you differentiate between CNVII palsy and a stroke?

Answer 17

Upper motor neurone lesions such as a stroke usually spare the forehead. They also affect the contra lateral side.
Lower motor neurone lesions affect the forehead and affect the ipsilateral side.

Question 18

How would you examine cranial nerve III?

Answer 18

Stand opposite patient and ask them to follow your finger. Draw a ‘H’ in the air. Watch for nystagmus - small amount is physiological, excessive is pathological.
Test pupillary reflex - should be consensual

Question 19

How would you examine cranial nerve V?

Answer 19

Test light touch and pain sensation on both sides on the face in each area. E.g. Forehead, cheeks, chin. Ask patient to close eyes and tell you when they can feel something.
Ask patient to clench jaw and feel muscle mass in ore-auricular region.
Sensation of anterior 2/3rds of tongue

Question 20

How would you examine cranial nerve VII?

Answer 20

Ask patient to:
Wrinkle up eyebrows and push against opposition
Scrunch up eyes and to keep them closed against opposition
Blow out cheeks and keep air in against opposition
Ask patient to smile and show teeth
Any changes in hearing?
Any changes in taste?

Question 21

What symptoms would you see in a complete oculomotor nerve palsy?

Answer 21

Eye would be down and out - unapposed action of superior oblique and lateral rectus
Complete Ptosis - Drooping of the eyelid
Dilated pupil on side affected only
Loss of accommodation reflex