facial nerve

1. K.SRINIVAS
Ist yr pg
Department of general medicine

2. FACIAL NERVE
 7th cranial nerve.
 Mixed cranial nerve.
motar
sensory
para sympathetic

3. ANATOMY
Supranuclear pathway
lower third of contralateral
precentral gyrus
Corona radiata
Genu of internal capsule.
Medial portion cerbralpeduncles
Pons
 Then decussate to converge on
the facial nucleus.

4.  Lower half of the face has
contralateral supranuclear
control
 Upper half has bilateral
control.
 Some of the corticobulbar
fibres descend in to the
aberrent pyramidal tract to
the medullary levels,decussate
there and ascend
contralaterally in to the dorsal
medulla to converge in to the
facial nucleus.

5. FACIAL NUCLEUS
 Special visceral efferent nerve.
 Branchiomotar nerve .
 Lies deep in the tegmentum of caudal pons.
 3 subnuclei
lateral
medial
dorsal

6. Sensory part
 Is formed by nervus intermedius (NI) of wrisberg.
 It forms 30% of the facial nerve.
 Sensory and parasympathetic division of facial nerve.
 Parasympathetic fibres arise from
superior salivatory and lacrimal nucleus
 The gustatory efferents end primarily in the nucleus of the
tractus solitarius.

8. Infranuclear pathway
 Facial nerve exits the pons in to the internal auditory
canal at ponto medullary junction.
 The nerve pierces the meninges and enter in to the
facial canal at the bottom of internal auditory meatus.
 3parts
labyrinthine
tympanic or horizantal
mastoid

9. Course and branches of facial nerve
 1st branch is greater superficial petrosal nerve.
 2nd branch is nerve to stapedius, arises from distal
tympanic or upper mastoid part.
 3rd branch is nerve to chordotympani arises slightly above
stylomastoid foramen.
 After the exit,posterior auricular,digastric and stylohoid
branches arise.
 In the parotid gland,it divides in to temporofacial and
cervicofacial division.

11.  Course and branches of facial nerve

13. Muscles of the face
 Temporal branch innervates frontalis.
corrugator .
upper part of orbicularis oculi.
occipitalis.
procerus.
 Zygomatic branch innervates lower and lateral
orbicularis oculi

14.  Buccal branch innervates orbicularis oculi
buccinator
zygomaticus
Nasalis
Levator anguli oris
levator labii superioris
 Mandibular branch innervates mentalis
risorius
triangularis
depressor labii inferioris
lower part of orbicularis oris
 Cervical branch innervates platysma

15. Clinical examination
Motor system:
 Inspection of the face.
 Tone,atrophy and fasciculations.
 Pattern of blinking
 Nasolabial fold.
 Palpebral fissure.
 Orbicularis oculi.
 Orbicularis oris.
 Platysma
 stapedius

17. Sensory system:
 Is limited to taste
 Peripheral receptors are present in the tongue
epithelium,also in the soft palate and epiglottis.
 5 major tastes:
bitter
sour
sweet
salty
umami(delicious or savory)
 Ageusia is complete inability to taste.
 Hypogeusia is taste perception delayed or blunted.

18. Secretory function:
 History and observation.
 Schirmer test filter strips are placed in the inferior
conjuctival sacs and left for 5min
 Lacrimal reflex is elicited by stimulation of nasal
mucosa (mechanical or chemical substances)

19. DISORDERS OF FUNCTION
 Tear-hear-taste-face
changes in these functions helps to localise the lesion
 2 types of facial weakness.
peripheral facial palsy(facial nucleus to t.branches)
cental facial palsy(supranuclear pathway)

20. PERIPHERAL FACIAL PALSY
 Complete paralysis.
 Affected side of the face is smooth.
 No wrinkles on the forehead.
 Eye is open.
 Inferior lid sags
 Nasolabial fold is flattened
 Angle of mouth droops
 Epiphora

21.  Bell’phenomenon(attempting to close the involved eye
causes upturning of the eyeball.
 Bergara-wartenberg sign.
 Platysma sign of babinski.
 Corneal reflex
The involved eye does not blink no matter which
side is stimulated

22. BELL’S PALSY
 Named after sir charless bell,
scottish surgeon,anatomist,and artist.
 Idiopathic facial paralysis.
 Frequently after viral infections
and immunization.
 Nerve damage is more common
in the labyrinthine part.
 Most common symptoms are increased tearing,pain in
and around the ear,and taste abnormalities

23. CRITERIA FOR BELL’S PALSY
 There should be diffuse peripheral facial palsy.
 Onset should with in a day or two.
 Paralysis reaching maximum with in 3 weeks.
 Full or partial recovery with in 6 months.

24. FACIAL SYNKINESIAS
 It is due to aberrant regeneration.
 Common after bell’s palsy and traumatic injury.
 Axons destined for one muscle regrow to innervate the other.
 Crocodiletears(gustatory lacrimal reflex).
 Aurico temporofacial syndrome
 Chordotympanic syndrome.
 On blinking,corner of the mouth deviates(marin amit sign)

25. Other causes of peripheral facial paralysis
 Motor neuron disease
 Mobius syndrome(congenital occulofacial paralysis)
 Millard-gubler syndrome
 Fovile syndrome
 Abscess,syringobulbia,demyelinating disease and trauma
in the pons
 Acoustic neuroma,meningioma in cerbello pontine angle.

26. Cont….
 Ramsay hunt syndrome.
 Diabetes milletus
 Hiv infection
 Lymes disease
 Fracture of petrous bones
 Melkerson syndrome is charecterised by recurrent attacks of
facial palsy.
 Polio myelitis

27. CENTRAL FACIAL PALSY
 Weakness of lowerface with relative sparing of upper face.
 Lower facial weakness is not as severe as in peripheral facial
palsy.
 2 variations:
volitional or voluntary facial asymmetry more
apparent with spontaneous expression.
emotional or mimetic facial asymmetry more
apparent with voluntary contraction.

28. Volitional facial palsy

29. CENTRAL FACIAL PALSY PERIPHERAL FACIAL PALSY

30. ABNORMAL FACIAL MOVEMENTS
 Facial dyskinesias.
 Hemifacial spasm due to intermittent compression by an
ectatic arterial loop in the post circulation,most often a
redundant loop of the AICA.
 Spastic paretic facial contracture instead of spasm there
may be fixed contracture.
 Facial myokymia is acontinous,involuntary muscle
quivering that has ripping worm like appearance.
multiple sclerosis,Gbsyndrome,CPA tumors,SAH.