2. The facial nerve Flashcards
Which cranial nerve is facial nerve?
CN 7
What fibers does facial nerve have?
Mainly motor, but also sensory (parasymp and taste)
Where is facial nerve motor nucleus located?
In pons
What is the function of motor nucleus of facial nerve?
- Facial expression
- Posterior belly of digastric
- Stylohyoid
Pathway of facial nerve
Out of the brainstem, cross the cerebellopontine angle, through internal auditory meatus, into facial canal of temporal bone. Gives off severeal branches before exiting the skull through stylomastoid foramen
Visceral efferent fibers of the facial nerve
- Superior salivary nucleus.
- Parasympathetic.
- Lacrimal gland, sublingual gland, submandibular gland
Visceral afferent fibers
- Solitary nucleus
- Taste fibers
- Anterior 2/3 of the tongue
Control of lower face muscles
Contralateral hemisphere
Control of upper face muscles
Control from both hemispheres (bilateral representation)
Facial muscles paralysed from lower motor neuron lesion
All facial muscles on affected side
Facial paralysis in upper motor neuron lesion
Paralyses the muscles in the lower half of the face contralteral side
Clinical examination of facial nerve
Facial muscles, taste, lacrimation/salvation
Lesion location? unilateral involvement of lower face with normal eye closure
Contralateral supranuclear lesion
Causes of contralateral supranuclear lesion
Vascular, tumor, demyelination, infection
Lesion location? unilateral involvement of the upper and lower face with defective eye closure
Ipsilateral nuclear or infranuclear lesion
Location where? bilateral involvement of upper and lower face
- Bilateral nuclear lesions
- Bilateral infranuclear lesions
- Muscle disease
Define Bell’s palsy
Acute paralysis of the face related to inflammation and swelling og facial nerve. Peripheral: ipsilateral, unilateral whole side
Etiology of Bell’s palsy
Idiopathic, viral infections
Clinical picture Bell’s palsy
- Bell’s phenomenon: unable to close affected eye, eyeball rotates up and out, loss of eyebrow movement, dropp of lower lip
- Pain over ipsilateral mastoid process
- Taste impairment
Treatment of Bell’s palsy
- High dose prednisolone 10 days
- Eye care (artificial tears)
- Protect affected eye
Which branch of facial nerve is resposnible for taste?
Chorda tympani nerve
Types of peripheral (lower motor neuron) facial nerve palsy
- Bell’s palsy
- Guillan Barré syndrome
- Lyme
- Infectious mononucleosis
- HSV reactivation + Herpes Zoster
Ramsey hunt syndrome
Hepres zoster infection of facial ggl. Severe pain, facial weakness.
- Affect CN facial and vestibulocochlear
- Fever
- Rash in the auditory canal + pinna
- Vertigo
- Sensorineural hearing loss
Branches of facial nerve responsible for facial expression
Temporal, zygomatic, buccal, marginal mandibular, cervical
Facial expression muscles
Auriculars
Corrugator supercilii,
Depressor anguli oris
Depressor labii inferioris
Levator labii superioris.
Mentalis
Nasalis
Occipitofrontalis
Orbicularis oculi
Orbicularis oris
Procerus
Risorius
Zygomaticus major and minor
