The document provides a comprehensive overview of the facial nerve, including its embryology, anatomical course, branches, functional components, and clinical considerations. The facial nerve controls muscles of facial expression, conveys taste sensations, and interacts with several head and neck ganglia. It discusses variations, testing methods, and potential surgical implications related to the facial nerve.

1. FACIAL NERVE
DR.SHASHANK BHUSHAN
DEPT.OF OMFS

2. 1. Introduction
2. Embryology
3. Nuclei of origin
4. Course & Relations
5. Branches of facial nerve
6. Functional components
7. Ganglia associated with facial nerve
8. Blood supply
10.Variations of nerve
11.Identification of facial nerve
12.Applied aspect
13.Conclusion

3. • The Facial nerve is the seventh of twelve
paired cranial nerves, it is a mixed nerve with
motor and sensory roots.
• It emerges from the brain stem between the
pons and the medulla, controls the muscles of
facial expression except levator palpebrae
superioris which is supplied by occulomotor
nerve

4. • It functions in the conveyance of taste
sensations from the anterior two thirds of the
tongue and oral cavity
• It also supplies preganglionic parasympathetic
fibres to several head and neck ganglia

5. Embryology
• The facial nerve is developmentally derived
from the hyoid arch, which is the second
branchial arch
• The motor division of facial nerve is derived
from the basal plate of the embryonic pons
• The sensory division originates from the
cranial neural crest

6. • 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

7. • By the end of the 4th week, the facial and
acoustic portions are more distinct
• The facial portion extends to placode
• The acoustic portion terminates on otocyst

9. Early 5th week, the
geniculate ganglion
forms from distal part
of primordium.
It separates into 2
branches: main trunk
of facial nerve and
chorda tympani

10. • Near the end of the 5th
week, the facial motor
nucleus is recognizable.
• The motor nuclei of VI
and VII cranial nerves
initially lie in close
proximity.
• The internal genu
forms as metencephalon,it
elongates and CN VI
nucleus ascends

11. Proximal branches form in the 6th week,
posterior auricular branch, branch of digastric.
Early 7th week, geniculate ganglion is well-
defined and facial nerve roots are recognizable.
The nervus intermedius arises from the ganglion
and passes to brainstem. Motor root fibers pass
mainly caudal to ganglion.

12. • Early 8th week, temporofacial and
cervicofacial divisions present.
• Late 8th week,5 major peripheral subdivisions
present

13. Nucleui of Origin
1. Motor nucleus of facial nerve :
• It lies in the lower part of the pons.
2. Superior salivatory nucleus :
• It lies in the pons lateral to the main motor
nucleus of VII and gives rise to secretomotor
parasympathetic fibers that pass in greater
superficial petrosal nerve and chorda
tympani.

14. • 3. Nucleus solitarus :
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.
• 4. Lacrimatory nucleus :
Through these fibers to acoustic meatus & back
of auricle through communication from auricular
branch of vagus. These fibers terminate in main
sensory nucleus & spinal nucleus of 5 th nerve.

16. COURSE OF FACIAL NERVE
• Internal course: the motor fibres passes
dorsally and medially forming a loop around
the abducent nucleus in the floor of the 4th
ventricle forming facial colliculus
• Superficial origin: at the pontomedullary
angle above the inferior cerebellar peduncle.

17. The facial nerve is formed mainly of
two parts:
• 1- Facial nerve proper (motor): arising from facial
motor nucleus in pons.
• 2- Nervus intermedius: it is the sensory root of
facial lies position between the facial proper and
vestibulcochlear nerve in the pontocerebellar
angle. Carrying para-sympathetic fibers (from
superior salivary nucleus) and taste fibers ( to the
solitarynucleus).

18. Course and relations:
I- Intracranial (intrapetrosal) course
II- Extracranial course

19. I- The intrapetrous course:
The nerve passes laterally with the vestibulocochlear
nerve (CN VIII) to the internal auditary meatus. At the
bottom of the meatus the nerve enters the facial bony
canal where it runs laterally above the vestibule of inner
ear.
Reaching the medial wall of the middle ear, it bends
sharply backwards above the promontory (forming its
genu) where the genicular ganglion is found.
It then arches downwards in the medial wall of the
middle ear to reach the stylomastoid foramen

22. II- Extracranial course:
• As it emerges from the stylomastoid foramen,
it runs forwards in the substance of the
parotid gland crosses the styloid process, the
retromandibular vein and the external carotid
artery.
• It divides behind the neck of the mandible into
its terminal branches which come out of the
anteromedial surface of the gland.

24. Branches
• Intracranial
Greater petrosal nerve
Nerve to stapaedius
Chorda tympani
• Intratemporal
Intrameatal
Labyrinthine
Tympanic
Mastoid nerve

25. • Extracranial
Posterior Auricular Nerve
Digastric nerve
Stylohyoid nerve
• The five terminal branches
Temporal branch
Zygomatic branch
Buccal branch
Marginal mandibular branch
Cervical branch

27. • Within the facial canal:
• 1- Nerve to stapedius: supplies the stapedius
muscle.
• 2- Greater superfacial petrosal nerve (GSPN) :
arises from the genicular ganglion

28. • The greater superficial petrosal nerve joins the
deep petrosal nerve from the sympathetic
plexus on the internal carotid artery in carotid
canal to form the nerve of the pterygoid canal
(vidian nerve) which passes through the
pterygoid canal to the pterygopalatine fossa
and ends in the pterygopalatine ganglion.

29. 3- Chorda tympani nerve:
• It arises from the facial nerve 6 mm above the
stylomastoid foramen and runs upwards to
perforate the posterior bony wall of the
tympanic cavity.
• It then passes forwards on the medial surface
of the tympanic membrane between its
fibrous and mucous layers crossing the
handle of the malleus.

30. • It comes out of the tympanic cavity through
the petrotympanic fissure to the
infratemporal fossa where it joins the lingual
nerve.
• Through the lingual nerve, it supplies both the
submandibular and sublingual salivary
glands by secretomotor fibres and taste fibers
from the anterior 2/3 of the tongue

31. II- At the exit from the stylomastoid foramen
1- Posterior auricular nerve:
to the auricularis posterior and the occipital
belly of the occipitofrontalis muscle.
2- Digastric branch:
to the posterior belly of digastric muscle
3- Stylohyoid branch:
to the stylohyoid muscle

32. TERMINAL BRANCHES
• The temporal branches of the facial nerve (frontal
branch of the facial nerve) crosses the zygomatic
arch to the temporal region, supplying the auricularis
anterior and superior, and joining with the
zygomaticotemporal branch of the maxillary nerve,
and with the auriculotemporal branch of the
mandibular nerve.

33. The more anterior branches supply the frontalis,
the orbicularis oculi, and corrugator supercilii,
and join the supraorbital and lacrimal branches
of the ophthalmic.
The temporal branch acts as the efferent limb of
the corneal reflex.

34. • The zygomatic branches of the facial nerve
(malar branches) run across the zygomatic
bone to the lateral angle of the orbit.
• Here they supply the Orbicularis oculi, and
join with filaments from the lacrimal nerve
and the zygomaticofacial branch of the
maxillary nerve.

35. • The Buccal Branches of the facial nerve
(infraorbital branches), of larger size than the
rest of the branches, pass horizontally forward
to be distributed below the orbit and around
the mouth.

36. • The marginal mandibular branch of the facial
nerve passes forward beneath the platysma
and depressor anguli oris.
• It supplies the muscles of the lower lip and
chin, and communicating with the mental
branch of the inferior alveolar nerve.

37. • The cervical branch of the facial nerve runs
forward
• It forms a series of arches across the side of
the neck over the suprahyoid region.
• One branch descends to join the cervical
cutaneous nerve from the cervical plexus;
others supply the Platysma. Also supplies the
depressor anguli oris.

39. Facial Nerve: Functional Components
1. Special Visceral Efferent/Branchial Motor
2. General Visceral Efferent/Parasympathetic
3. General Sensory Afferent/Sensory
4. Special Visceral Afferent/Taste

41. GANGLIA ASSOCIATED
WITH THE FACIAL NERVE
• Geniculate ganglion
• Submandibular ganglion
• Pterygopalatine ganglion

42. • Geniculate Ganglion
The geniculate ganglion (from Latin genu, for
"knee") is an L-shaped collection of fibers and
sensory neurons of the facial nerve located in
the facial canal of the head.

44. Submandibular Ganglion
The submandibular ganglion is small and
fusiform in shape. It is situated above the deep
portion of the submandibular gland, on the
hyoglossus muscle, near the posterior border of
the mylohyoid muscle.

45. Pterygopalatine Ganglion
• The pterygopalatine ganglion (meckel's
ganglion,nasal ganglion or sphenopalatine
ganglion) is a parasympathetic ganglion found
in the pterygopalatine fossa.

46. Facial Nerve blood supply
The facial nerve gets it’s blood supply from 4
vessels:
Anterior inferior cerebellar artery – at the
cerebellopontine angle
Labyrinthine artery (branch of anterior inferior
cerebellar artery) – within internal acoustic meatus
Superficial petrosal artery (branch of
middlemeningeal artery) – geniculate ganglion and
nearby parts

47. • Stylomastoid artery
(branch of posterior auricular artery) – mastoid
segment
• Posterior auricular artery supplies the facial
nerve at & distal to stylomastoid foramen
• Venous drainage parallels the arterial blood
supply

48. Variations of Facial Nerve
• 1. Buccal branch usually single, two branches
in 15% cases
• 2. Marginal mandibular branch – pass below
the lower border of mandible, incidence
varying between 20-50%
• 3. Cervical branch – 20% cases, two branches

49. 4. Katz and Catalano reported cases (3%)
presenting two main trunks, known as the major
and minor trunks of facial nerve.
5. Baker and Conley reported trifurcation,
quadrifurcation, or even a plexiform branching
pattern of the trunk of the facial nerve

51. Testing of Facial Nerve Branches
Testing the temporal branches of the facial nerve
• To test the function of the temporal branches of
the facial nerve, a patient is asked to frown and
wrinkle his or her forehead.
• Testing the Zygomatic branches of the facial
nerve
The patient is asked to close their eyes tightly.

52. • Testing the buccal branches of the facial
nerve
• 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.

53. • The marginal mandibular nerve may be
injured during surgery in the neck region,
especially during excision of the
submandibular salivary gland or during neck
dissections.

54. Applied Aspect of
Facial Nerve

55. • Damage to facial nerve is possible in severe
maxillofacial surgeries with basilar skull
fractures anywhere in the area of course of
the nerve and would result in ipsilateral
paralysis of the muscles of facial expression
• Of concern to the surgeon is the close
proximity of the main trunk of facial nerve
where it exits the stylomastoid foramen and
mandibular condyle

57. After exiting the stylomastoid foramen, which is
situated posterolateral to stylomastoid process,
the nerve enters the substance of parotid gland
where it divides into its upper and lower
divisions just posterior to the mandible.
The approximate distance from the lowest
pointof the external bony auditory meatus to
the bifurcation of the facial nerve is 2.3 cm

58. • Posterior to the parotid gland,the nerve is
atleast 2cm deep into the skin surface,from
this point the two branches curve around the
posterior mandible,where they form plexus
between the parotid gland and the masseter
muscle

59. The terminal branches of facial nerve then
spread in a fan like fashion as five separate
nerves
Temporal branch :
It exits the parotid gland anterior to superficial
temporal artery,During an open approach to
the TMJ, violation of this branch is possible

60. Zygomatic Branch :
• Its course is antero superior crossing the
zygomatic bone
• Inadvertent damage may occur to this nerve
during open reduction of zygomatic arch or
with the use of a byrd screw or zygomatic
hook during closed approaches

61. Buccal Branch:
• It runs almost horizontally and will often
divide into separate branch above and below
parotid duct as it runs anteriorly.
• Injury is possible in association with soft tissue
trauma to the cheek region

62. Marginal mandibular branch:
• It extends anteriorly and inferiorly within the
substance of parotid gland, there may be two or
three branches of this nerve.
• These branches run anteriorly parallel to inferior
border of mandible and in some cases the course
of the nerve is above the inferior border.
• In essentially all cases the nerve is located above
the inferior border of mandible beyond the facial
artery.

63. • The marginal mandibular branch is an
important structure encountered at the
inferior border of the mandible just beneath
the platysma muscle fibres.
• During an open approach to the mandibular
angle and body area.

64. • For this reason, an initial incision made
approximately 1 to 1.5cm below the inferior
border which prevents direct exposure or
trauma to the nerve

65. • Cervical Branch:
The cervical branch exits the parotid gland
above its inferior pole and runs downwards
underneath the platysma muscle.

66. • The surgeon must be mindful of the facial
nerves intimate involvement with the TMJ,
specially when performing surgical
approaches to the joint.
• The temporal and zygomatic branches are at
increased risk during pre auricular approach
and the marginal mandibular branch during
submandibular approach
• The intra oral approach to the TMJ has
minimal risk to the branches of facial nerve
which is its major advantage

67. Identification of Facial Nerve
The four commonly used landmarks in
identification of the facial nerve trunk during
surgical procedures are:
The tragal pointer
The posterior belly of digastric muscle
The junction of the bony cartilaginous ear canal.
The tympanomastoid suture

69. Pre-auricular incision with its
variations:
The pre-auricular incision is sited just anterior
to pinna or alternatively around the tragus and
at the junction of the ear and the scalp
superiorly. It is then directed obliquely forwards
and upwards at an angle of 45°. Usually
posterior branch of superficial temporal artery
requires ligation while its anterior branch and
auriculotemporal nerve are retracted anteriorly.

71. Al Kayat and Bramley (1979) modification -
used for a wider exposure.
a question mark shaped skin incision which avoids main
vessels and nerves
About 2 cm above the malar arch, the temporalis fascia
splits into 2 parts, which can be easily identified by fat
globules between 2 layers which form an important
landmark.
In this, temporal facia and superficial temporal artery are
reflected with skin flap. Later helps in better healing of the
flap.
Under no circumstances should the inferior end of the skin
incision be extended below the lobe of the ear as it
increases the risk of damage to main trunk of facial nerve. It
is particularly important in children where it may be quite
superficial.

72. The length of the facial nerve which is visible to
the surgeon is about 1.3 cm. It divides into
temporofacial and cervicofacial divisions at a
point vertically below the lowest part of bony
external auditory meatus at a distance of 2.3 +
0.28cm; shortest distance being 1.5 cm.
The distance between lowest point of posterior
glenoid tubercle to bifurcation of facial nerve is
3.0 + 0.3 cm; shortest distance being 2.4 cm
(Alkayat and Bramley, 1979).

74. CLINICAL ANATOMY
OF FACIAL NERVE

75. 1. Supra nuclear type:
• Features:
a) Paralysis of lower part of face (opposite side)
b) Partial paralysis of upper part of face
c) Normal taste and saliva secretion
d) Stapedius not paralysed

77. 2. Nuclear type:
Millard cobbler syndrome
• Features:
a) Paralysis of facial muscle (same side)
b) Paralysis of lateral rectus
c) Internal strabismus

78. 3. Infranuclear lesion
a) At internal acoustic meatus
Features:
i. Paralysis of secretomotor fibers
ii. Hyper acusis
iii. Loss of corneal reflex
iv. Taste fibers unaffected
v. Facial expression and movements paralysed

80. b) Injury distal to geniculate ganglion
Features:
i. Complete motor paralysis (same side)
ii. No hyperacusis
iii. Loss of corneal reflex
iv. Taste fibers affected
v. Facial expression and movements paralysed
vi. Pronounced reaction of degeneration

81. c) Injury at stylomastoid foramen
• Condition known as Bell’s Palsy
Idiopathic and sudden onset of ipsilateral lower
motor neuron facial palsy.

82. Bell palsy

83. • First described more than a century ago by Sir
Charles Bell
• 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

84. • Bell's phenomenon is the upward diversion of
the eye ball on attempted closure of the lid is
seen when eye closure is incomplete.

85. I.Unilateral involvement
II. Inability to smile, close eye or raise eyebrow
III. Whistling impossible
IV. Drooping of corner of the mouth
V. Inability to close eyelid (Bell’s sign)
VI. Inability to wrinkle forehead
VII. Loss of blinking reflex
VIII.Slurred speech
IX. Mask like appearance of face
X. Loss/ alteration of taste

86. 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

87. Surgical treatment
Facial nerve decompression
Indication:
Completely paralysis
Appropriate time for surgery is 2-3 weeks after
paralysis

88. Ramsay Hunt syndrome Symptoms:
Facial paralysis
Ear pain
Vesicles
hearing loss

89. 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.

90. • Neurosarcoidosis
• Facial nerve paralysis, sometimes bilateral, is
a common manifestation of neurosarcoidosis
(sarcoidosis of the nervous system).
• Itself a rare condition.

91. • Moebius syndrome (congenital facial
diplegia)
• Abnormal VI ,VII,XII Nerve nuclei
• Facial Nerve absent / smaller
• Congenital Extra ocular muscle & facial palsy

92. Cardiofacial Syndrome
• Unilateral facial paralysis involving only the
lower lip and congenital heart disease
• The facial paralysis in these patients involves
only those muscles concerned with pulling the
lower lip downwards and outwards
• These are the mentalis, depressor labii
inferioris and depressor anguli oris muscles

93. • All are supplied by the mandibular marginal
branch of the facial nerve.
• Lesions of this nerve have been recognized in
adults and children for many years.
• The paralysis is only recognizable when the
patient talks, smiles or cries.

94. Treacher collins syndrome
(mandibulo facial dysostosis)
There is a set of typical symptoms within Treacher Collins
Syndrome
The OMENS classification was developed as a
comprehensive and stage-based approach to differentiate
the diseases.
O; orbital asymmetry
M; mandibular hypoplasia
E; auricular deformity
N; nerve development
S; soft-tissue disease

95. • Facial Nerve involvement in Treacher collins
syndrome
N0: No facial nerve involvement.
N1: Upper facial nerve involvement (temporal or
zygomatic branches).
N2: Lower facial nerve involvement (buccal,
mandibular or cervical).
N3: All branches affected.

96. Goldenhars syndrome
(oculoauriculo vertebral dysplasia)
• It is a wide spectrum of congenital anomalies
that involves structures arising from the first
and second branchial arches.
• Features of hemi facial microsomia, anotia,
vertebral anomalies, congenital facial nerve
palsy.

98. Conclusion
Surgeons have to pay attention to minimize the risk of
complication during parotidectomy.
The best means of reducing iatrogenic facial nerve injury, in
parotid surgery, still remains a clear understanding of the
anatomy, good surgical technique with the use of multiple
anatomic landmarks.
Pre-operative discussion and consent for surgery, tailored
according to the age and health of the patient as well as the
behavior of the tumor, are mandatory.
Furthermore, the patient has to be informed about the
cosmetic sequelae of the incision and all patients have to be
told that facial nerve paralysis or paresis is possible and can
be partial or total, temporary or permanent.