Session 8 - Oculomotor, Trigeminal And Facial Nerve Flashcards
(21 cards)
What symptoms would you see in a palsy of the oculomotor nerve proper?
Eye would be in a down and out position
Complete ptosis
What is the oculomotor nerve ‘proper’
Somatic element of the nerve only
Does not contain the sympathetic fibres
Why do you get pupil dilation if there is palsy of the oculomotor nerve?
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.
What is the origin of the oculomotor nerve and from where does it exit the cranium?
From the oculomotor nucleus
Leaves via superior orbital fissure
What is the site of origin of the parasympathetic nerves that hitch-hike the oculomotor nerve?
Edinger-Westphal nucleus - midbrain
What muscles does the oculomotor nerve supply?
Inferior oblique Superior rectus Inferior rectus Medial rectus Levator palpebrae superioris
Where would the lesion be if there was only a palsy of the oculomotor nerve proper?
Distal to ciliary ganglion
E.g. Pupil sparing third palsy
What are the branches of the trigeminal nerve?
Opthalmic
Maxillary
Mandibular
What nerve is affected in Harlequin syndrome?
CNV
What are the symptoms of harlequin syndrome?
Affects Ipsilateral side
Loss of sensation to 1/2 face
Anhydrosis
Vasomotor dysfunction
What is the origin of the facial nerve?
Facial motor nucleus - pons
Nucleus solitarius - sensory afferents
Superior salivatory nucleus - visceral afferents
What are the targets of the nucleus solitarius?
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
What are the branches of the facial nerve? (E.g motor component)
Ipsilateral
Temporal Zygomatic Buccal Mandibular Cervical
Describe the origin and course of the facial nerve (motor)?
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.
Give examples of when the facial nerve can be damaged:
Parotidectomy
Forceps delivery of baby
Tumours of parotid gland
Parotitis
What are the clinical signs of complete CNVII nerve palsy?
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
How could you differentiate between CNVII palsy and a stroke?
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.
How would you examine cranial nerve III?
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
How would you examine cranial nerve V?
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
How would you examine cranial nerve VII?
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?
What symptoms would you see in a complete oculomotor nerve palsy?
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
