Facial nerve PRESENTATION

Guided by
Dr. SHOBHA
1
THE FACIAL
NERVE

CONTENTS
2
• Terminologies
• Introduction to Cranial Nerves
• Facial nerve :
• Introduction
• Embryology
• Nuclei of origin
• Functional components
• Courses
• Branches and distribution
• Ganglions associated
• Applied aspects
• Conclusion
• References

3
• Nerve : A bundle of fibers that uses chemical and electrical
signals to transmit sensory and motor information from
one body part to another.
• Sensory Nerve : A nerve that passes impulses from receptors
towards or to the CNS.
• Motor Nerve : Any nerve that transmits impulses from the
CNS to muscles/ organs.
Essentials of medical physiology by k sembulingam and p sembulingam 4th edition

4
• Afferent Nerve: A nerve conveying impulses from the periphery to
the CNS.
• Efferent Nerve: A nerve conveying impulses from the CNS to the
periphery.

5
Handbook of local anesthesia- Stanley F Malamed 5th edition

6
Nucleus Ganglion
Similar group of nerve cell bodies ( in
form and function) located inside the
CNS.
Make the grey matter, where
processing of information occur.
Similar group of nerve cell bodies ( in
form and function) located outside the
CNS.
Mostly sensory neurons that gather
nerve information.

7
• Pre-ganglionic fibers: In the ANS, fibers from CNS to the
ganglion.
• Post-ganglionic fibers: In the ANS, fibers from ganglion to the
effector organ.

8
• Synapse: It is the site of functional contact between the axonal membrane
of one neuron and the membrane of the neuron of effector cell next in line.
• Neuralgia: Intense burning or stabbing pain
caused by irritation or damage to a nerve.

9
Brief overview of cranial nerve
functional components
• General somatic and visceral components
Somatic→ non-visceral structures including skin, muscles, tendons, joints, etc.
Visceral→ organs of the body cavity, smooth muscle, vessels, and glands.
• Special sensory and motor components
Special sensory → hearing, seeing, smelling, balancing and tasting.
Special motor → those innervating skeletal muscles derived embryologically
from pharyngeal arches.

B.D.Chaurasia’s Human Anatomy 4th edition

• Facial nerve course, branching pattern, and anatomical relationships
are established during the first 3 months of prenatal life.
• The nerve is not fully developed until about 4 years of age
• The first identifiable facial nerve tissue is seen at the third week of
gestation-facioacoustic primordium or crest
12
The Facial Nerve – May’s 2nd edition

Weeks Features
0-4 Appearance of facio-acoustic
primordium
Splitting of facial nerve
Presence of chorda tympani
5-6 Separation of facial and acoustic
nerves
Appearance of geniculate
ganglion
Formation of GSPN
7 Formation of peripheral branches
8 Formation of fallopian canal
10-15 More extensive branching
13

15
• Lies in the lower part of the pons.
Motor nucleus of
facial nerve
• Lies in the pons lateral to the main motor
nucleus of facial nerve and gives rise to
secretomotor parasympathetic fibers that pass in
greater superficial petrosal nerve & chorda
tympani.
Superior
salivatory
nucleus

16
• It lies in the medulla, receives the taste
sensation from the anterior 2/3 of the
tongue via the central processes of the cells
of the geniculate ganglion of the facial
nerve.
Lacrimatory
nucleus
• Through these fibers to acoustic meatus
and back of auricle through
communication from auricular branch of
vagus. These fibers terminate in main
sensory nucleus & spinal nucleus of
trigeminal nerve.
Nucleus of
tractus solitarius

FUNCTIONAL COMPONENTS
17B.D.Chaurasia’s Human Anatomy 4th edition

COURSE
 Intra cranial course
 Intra pontine course
 Attachment to the brain
stem
 Course through posterior
cranial fossa
 Intrapetrous course
 Meatal part
 Facial canal part
 labyrinthine segment
 Tympanic segment
 Mastoid segment
 Exit from the cranium
 Extra cranial course

INTRACRANIAL COURSE
• Intrapontine Course: the
fibers from the motor nucleus
course through the pons
taking a sharp bend around
the abducent nucleus
producing internal genu of
the facial nerve and they
leave the pons between the
nucleus of spinal tract of
trigeminal and the facial
nucleus. 20B.D.Chaurasia’s Human Anatomy 4th edition

Attachment to the brain
stem: the sensory and
motor roots are attached to
the lateral aspects of the
pontomedullary junction.

• Course through posterior cranial fossa:
from the superficial attachment to the brainstem to the opening of the
internal acoustic meatus the two roots of the facial nerve pass laterally
and forward in the cerebellopontine angle along with vestibulochoclear
nerve and labyrinthine artery. These structures together enter the
internal acoustic meatus.
22

INTRAPETROUS COURSE
 Meatal segment: is in the
internal acoustic meatus where
the motor root is lodged in a
groove on the antero-inferior
surface of the vestibulochoclear
nerve but the sensory root
separates them. At the bottom of
the internal acoustic meatus , the
two roots unite to form the trunk
of the facial nerve and then it
enters the facial canal.

• Facial canal part: is divided
into 3 segments:
i. Labyrinthine segment :
passes laterally above the
vestibule of the inner ear to
reach the anterior end of
the medial wall of the
middle ear. Here it bends
backwards at a sharp turn
called the external genu of
the facial nerve which has
the geniculate ganglion
on it.

ii. Tympanic segment: passes
backwards in the medial wall of
the middle ear till it reaches the
posterior end of this wall. It is
also known as the horizontal
part.

iii. Mastoid segment or
vertical segment: begins
at the posterior end of the
medial wall and passes
downwards in relation to
the posterior wall of the
middle ear to reach the
stylomastoid foramen.

EXIT FROM THE CRANIUM
• The facial nerve leaves
the cranium through

EXTRACRANIAL COURSE
• The facial nerve crosses the lateral
side of the base of the styloid
process. It enters the
posteromedial surface of the
parotid gland.
• Within the gland it runs forward for
a short distance superficially to the
retromandibular vein and external
carotid artery and then divides into
a)temperofacial
b)cervicofacial trunks.
• The terminal branches radiate like
a goose’s foot from the anterior
border of the parotid gland.
28

29
• Greater petrosal nerve
• The nerve to stapedius
• The chorda tympani1.Within the facial canal
• Posterior auricular
• Digastric
• Stylohyoid
2.At its exit from the
stylomastoid foramen
• Temporal
• Zygomatic
• Buccal
• Marginal mandibular
• Cervical
3.Terminal branches
within the parotid gland

WITHIN THE FACIAL CANAL

GREATER PETROSAL NERVE
31
• Arises from the geniculate
ganglion.
• consists chiefly of sensory
branches which are distributed to
the mucous membrane of the
soft palate; but it probably
contains a few motor fibers
which form the motor root of the
sphenopalatine ganglion.
• Action:
1. Sensation of light touch,
temperature, and pain from the
soft palate.
2. Taste from the hard and soft
palate

NERVE TO THE STAPEDIUS
32
• Arises opposite the pyramid of
the middle ear, and supplies
the stapedius muscle
• Action :the muscle dampens
excessive vibrations of the
stapes caused by high-pitched
sounds.
• In paralysis of the muscle,
even normal sounds appear
too loud and is known as hyper
acusis.

THE CHORDA TYMPANI
33
• Arises in the vertical part of the
facial canal about 6 mm above
the stylomastoid foramen.
It carries:
1. Preganglionic fibres to the
submandibular ganglion for
the supply of the
submandibular and
sublingual salivary glands
2. Taste fibres from the anterior
two-thirds of the tongue
except the circumvallate
papillae.

POSTERIOR AURICULAR NERVE
35
POSTERIOR AURICULAR BRANCH
• Arises just below the
• Supplies :
 Auricularis posterior
 Occipitalis
 Intrinsic muscles of back of
auricle

THE DIGASTRIC BRANCH
• Arises close to the
posteriorauricular
nerve.
• It is short and
supplies the
posterior belly of
digastric .
36
DIGASTRIC BRANCH

STYLOHYOID BRANCH
• It arises with the
digastric branch.
• It is long and
supplies the
stylohyoid muscle.
37
STYLOHYOID
BRANCH

TERMINAL BRANCHES WITHIN THE PAROTID
GLAND

Internal acoustic meatus Vestibulocochlear nerve
Geniculate ganglion A. Greater petrosal nerve
B. Lesser petrosal nerve
C. External petrosal nerve
Facial canal Vagus nerve
Stylomastoid foramen IX & X cranial nerve
Greater auricular nerve
Auriculotemporal nerve
Behind ear Lesser occipital
Face V nerve
Neck Transverse cutaneous nerve

42
Geniculate ganglion
• Located on the 1st bend of
facial nerve, in relation to the
medial wall of the middle ear.
• It is a sensory ganglion.
• The taste fibers present in the
nerve are peripheral processes
of pseudounipolar neurons
present in the geniculate
ganglion.

43
Submandibular ganglion
• Parasympathetic ganglion.
• For relay of secretomotor
fibres to the submandibular
and sublingual glands.

44
Pterygopalatine ganglion
• Parasympathetic ganglion.
• Secretomotor fibers meant for
the lacrimal gland relay in this
ganglion.

The facial nerve is responsible for:
 -Contraction of the muscles of the face
 -Production of tears from a gland (Lacrimal gland)
 -Conveying the sense of taste from the anterior 2/3rd of the
tongue (via the Chorda tympani nerve)
 -The sense of touch at auricular conchae

46

47
Temporal branches
• The patient is asked to frown and wrinkle his or her forehead
(frontalis and corrugator supercilli)
Zygomatic branches
• The patient is asked to close their eyes tightly(orbicularis
occuli)
Buccal branches
• Puff up cheeks (buccinator).
• Smile and show teeth (orbicularis oris) .
• Tap with finger over each cheek to detect ease of air expulsion
on the affected side.

48
FACIAL NERVE LESIONS:
 Supra-nuclear type
 Infra-nuclear type
 Peripheral lesions
• Injury at internal acoustic
meatus
• Injury distal to geniculate
ganglion
• Injury at stylomastoid foramenThe Facial Nerve – May’s 2nd edition

SUPRA-NUCLEAR TYPE
• It is usually a part of hemiplegia-is the lower part of the
face that is chiefly affected, while the upper part
remains unaffected,i.e.,the frontalis and orbicularis
oculi muscles escape.
49

INFRA-NUCLEAR TYPE:
The lower motor neuron lesion of facial nerve cause paralysis of all
facial muscles on the same side.
50

 Peripheral Lesion
At internal acoustic
meatus
Features
• Paralysis of
secretomotor fibers
• Hyperacusis
• Loss of corneal
reflex
• Taste fibers
unaffected
• Facial expression
and movements
paralysed 51
Injury distal to
geniculate ganglion
Features:
• Complete motor
paralysis (same side)
• No hyper acusis
• Loss of corneal reflex
• Taste fibers affected
• Facial expression and
movements paralysed
• Pronounced reaction
of degeneration
Injury at
stylomastoid
foramen
Condition known
as Bell’s Palsy

52

BIRTH
 Forceps delivery
 Dystrophia myotonica
 Moebius' syndrome (facial
diplegia associated with other
cranial nerve deficits)
53

TRAUMA
 Basal skull fracture
 Facial injuries
 Penetrating injury to middle
ear
 Altitude paralysis
(barotrauma)
 Scuba diving (barotrauma)
54

INFECTIONS
 External otitis
 Otitis media
 Mastoiditis
 Chicken pox
 Herpes zoster (Ramsay Hunt
 syndrome)
 Encephalitis
 Poliomyelitis (type I)
 Mumps
55
 Leprosy
 Coxsackievirus
 Malaria
 Syphilis
 Scleroma
 Tuberculosis
 Botulism
 Mucormycosis
 Lyme disease

TOXIC
 Thalidomide
 Tetanus
 Diphtheria
 Carbon monoxide
56

METABOLIC
 Diabetes mellitus
 Hyperthyroidism
 Pregnancy
 Hypertension
 Acute porphyria
57

NEOPLASTIC
 Facial nerve tumour
 Leukaemia
 Meningioma
 Haemangioblastoma
 Sarcoma
 Carcinoma (invading or
metastatic)
 Haemangioma of tympanum
 Facial nerve tumour
(cylindroma)
 Schwannoma
 Teratoma
 Fibrous dysplasia
 von Recklinghausen's disease 58

IATROGENIC
 Mandibular block anesthesia
 Head and neck surgery
59

IDIOPATHIC
 Myasthenia Gravis
 Guillain-Barre Syndrome
 Sarcoidosis
 Familial Bell's Palsy
60

61
Sun MZ, Oh MC, Safaee M, Kaur G, Parsa AT. Neuroanatomical correlation
of the House-Brackmann grading system in the microsurgical treatment of
vestibular schwannoma. Neurosurgical focus. 2012 Sep;33(3):E7.

62
BACKGROUND OF BELL’S PALSY
 First described more than a century
ago by Sir Charles Bell
 Yet much controversy still
surrounds its etiology and
management
 Bell’s palsy is certainly the most
common cause of facial paralysis
worldwide
Shafer’s Textbook of Oral Pathology -5th edition

63
DEMOGRAPHICS OF BELL'S PALSY
Race: slightly higher in persons of Japanese
descent.
Sex: No difference exists
Age: highest in persons aged 15-45 years.
Bell’s palsy is less common in those younger than
15 years and in those older than 60 years.

PATHOPHYSIOLOGY OF BELL’S PALSY
• Main cause of Bell's palsy is
latent herpes viruses
(herpes simplex virus type 1
and herpes zoster virus),
which are reactivated from
cranial nerve ganglia
• Polymerase chain reaction
techniques have isolated
herpes virus DNA from the
facial nerve during acute
palsy
64

FEATURES OF BELL’S PALSY
• Unilateral involvement
• Inability to smile, close eye or
raise eyebrow
• Whistling impossible
• Drooping of corner of the mouth
• Inability to close eyelid (Bell’s
sign)
• Inability to wrinkle forehead
• Loss of blinking reflex
• Slurred speech
• Mask like appearance of face
• Loss/ alteration of taste
65

COURSE AND PROGNOSIS
Partial paralysis always resolves completely within a few
weeks.
Recovery from complete paralysis takes longer (months) and
is complete in only about 60-70% of cases.
Approximately 15% of patients are left with troublesome
residual palsy and or synkinesis.
66

MANAGEMENT OF BELL’S PALSY
67
EYE CARE
 It focuses on protecting the
cornea from drying and abrasion
due to problems with lid closure
and the tearing mechanism.
 Lubricating drops should be
applied hourly during the day
and a simple eye ointment
should be used at night.

 Treatment consists of Infra-red radiation on affected
 side of the face at 2 ft (60cm) ,followed by interrupted galvanism on
affected side
 Treatment was given daily at first few weeks & later thrice weekly.
 All patients are instructed to massage the face daily
68

MEDICAL TREATMENT
• Corticosteroids :
• Prednisolone 1 mg/kg/day 7-10 days
• Corticosteroids combine with antiviral drug is better
• Acyclovir 400 mg 5 times/day
• Famciclovir and valacyclovir 500 mg bid
69

SURGICAL TREATMENT
Facial nerve decompression
INDICATION:
 Completely paralysis
 ENoG less than 10% in 2 weeks
 Appropriate time for surgery is 2-3 weeks after paralysis
70

RAMSAY HUNT SYNDROME
• A special form of zoster(herpes
zoster) infection of the
geniculate ganglion with the
involvement of the external ear
and the oral mucosa.
SYMPTOMS:
Facial paralysis, Ear pain,
Vesicles, Sensorineural
hearing loss, Vertigo
71

ACUTE AND CHRONIC OTITIS MEDIA
• Otitis media is an infection in
the middle ear, which can
spread to the facial nerve and
inflame it, causing
compression of the nerve in its
canal
72

MELKERSSON ROSENTHAL SYNDROME
• Recurrent attacks of facial paralysis
• Associated with multiple episodes of non-
pitting, non-inflammatory painless edema
of the face
• Chelitis granulomatosa
• Fissured tongue
73

MOBIUS SYNDROME
• Results from the underdevelopment
of cranial nerve VI and VII
• The VI cranial nerve controls lateral
eye movement, and the VII cranial
nerve controls facial expression and
is manifested in infancy.
• Because of partial or complete
facial paralysis, the infant exhibits :
 no change in facial
expression (mask like
appearance)
Failure to close eyes during
sleep.
Mouth may remain partially
open
74Shafer’s Textbook of Oral Pathology -5th edition

CROCODILE TEARS SYNDROME
Due to injury to facial nerve proximal
to the geniculate ganglion, there may
be a misdirection of nerve fibres to
lacrimal gland instead of going to
submandibular gland, through the
greater petrosal nerve. As a result
patient lacrimates is termed as
‘crocodile tear syndrome’ and can be
treated by dividing greater petrosal
nerve.
75

CONCLUSION
81
The facial nerve is a highly specialized nervous system and is
genetically programmed to perform in a specific fashion. The
facial nerve is not just a pure voluntary motor nerve but
comprises parasympathetic, general sensory, and special
sensory components as well. Facial nerve has numerous
interconnection with other cranial, parasympathetic, and
sympathetic nerves along its course, which helps to explain
many of the referred pain syndromes encountered in head and
neck pathology and also why residual functions exists
following apparently denervating facial nerve injury.

REFERENCES
82
• B.D.Chaurasia’s Human Anatomy 4th edition
• Gray’s anatomy 2nd edition
• The Facial Nerve – May’s 2nd edition
• Handbook of local anesthesia- Stanley F Malamed 5th edition
• Shafer’s Textbook of Oral Pathology -5th edition

• Atlas of clinical gross anatomy- Kenneth , John , Pedro.
• Sun MZ, Oh MC, Safaee M, Kaur G, Parsa AT.
Neuroanatomical correlation of the House-Brackmann grading
system in the microsurgical treatment of vestibular
schwannoma. Neurosurgical focus. 2012 Sep;33(3):E7.
83

Facial nerve PRESENTATION

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