2. LEARNING OBJECTIVE
• To understand the distribution
and supply of the facial nerve
as well as the branches in detail.
• To know the surgical aspects in
relation to the facial nerve and
also the diseases or syndromes
associated.
5. HISTORY
• The Scottish Surgeon Sir Charles
Bell’s discovered the nerve of
facial expression in 1829, with 3
reported cases of facial paralysis
due to facial nerve trauma.
• In 1879, the German surgeon
Drobnik performed the first
facial-spinal accessory
anastomosis.
6. • Decompression was the primary focus of facial nerve
surgery from 1908 to 1969.
• 1970 to 2000 ,was known as the bottleneck period in
honour of contributors such as Ugo Fisch who worked on
the proximal portion of the nerve.
7. EMBRYONIC DEVELOPMENT
The main pattern of the nerves complex course,
branching pattern and relationships is
established during the 3rd month of prenatal life.
The nerve is not fully developed until 4 years of
age.
At the end of the 3rd week of prenatal life tissue
which will become the seventh cranial nerve
appears.
At this stage, a collection of neural crest cells
appears dorsolateral to the still open
rhombencephalon and just rostral to the otic
placode.
8. Because the cell collection also gives
rise to the eight cranial nerve, it is
referred to as the facioacoustic
primordium or crest.
Simultaneously ,the otic placode
invaginates to form the otocyst from
which the membranous labyrinth of
the inner ear arises.
The facial portion of the primordium
is a narrow cell column which
extends ventrally to a thickened
area of the surface ectoderm called
a placode.
This placode is located on the
surface of the upper portion of the
second pharyngeal arch.
9. The distal segment is ill defined but separates into almost
two equal branches: one which courses caudally into the
mesenchyme of the second pharyngeal arch and
represents the future MAIN TRUNK OF THE FACIAL NERVE
and the other which curves rostrally into the first arch to
become the chorda tympani nerve.
10. POSTNATAL DEVELOPMENT
• At birth, the mastoid process is absent, and the tympanic
ring is narrow.
• The nerve assumes a deeper and more protected position
between 2 and 4 years of age as the tympanic ring enlarges
and the mastoid process forms.
• Thus, in the new born and until 4 years of age, the facial
nerve lies just under the bone and is quite vulnerable to
injury.
• High incidence of facial nerve injury during surgery in
infants is due to the fact that the marginal nerve runs over
the mandible is very fine and may require magnification for
identification.
12. SEGMENTS OF THE
FACIAL NERVE
I MUST LEARN TO MAKE
EXPRESSIONS
• I- Intracranial
• M- Meatal
• L-Labyrinthine
• T- Tympanic
• M-Mastoid
• E- Extracranial
13. INTRACRANIAL PORTION OF THE FACIAL NERVE
• The intracranial portion of the
facial nerve may be divided into:
1. the voluntary motor cortex
2. Genu of internal capsule
3. Extrapyramidal system
4. Pontine-facial nerve nucleus
5. Cerebellopontine angle
14. • CORTEX AND INTERNAL CAPSULE:
• The voluntary responses of the facial
muscles, such as smiling on
command are dependent on the
discharges from the appropriate
regions of the cerebral cortex, the
motor face area which is situated in
the PRECENTRAL GYRUS.
SUPRANUCLEAR ANATOMY
15. ADD A SLIDE TITLE - 6
• Discharges from the motor face
area are carried through the
fascicles of the corticobulbar tract
to the internal capsule ,then
through the midbrain to the lower
brainstem where they synapse in
the facial nerve nucleus located in
the pons.
• The corticobulbar tracts arising
from the cortical representation of
the upper face area cross and
recross in reaching the pontine
facial motor nucleus. The tracts to
the lower face are crossed only.
16. EXTRAPYRAMIDAL SYSTEM
• The extrapyramidal system consists
of the basal ganglia and the
descending motor projections
other than the fibers of the
pyramid or corticospinal tracts.
• This system provides for automatic
associated movements and
spontaneous, emotional, mimetic
human facial language which
accompanies the more precise
voluntary responses.
• The interplay between pyramidal
and extrapyramidal systems
accounts for tonus and stabilization
of motor responses.
19. PONTINE NUCLEUS
• The facial motor nucleus contains approximately 7000 neurons seated
in the lower third of the pons beneath the fourth ventricle.
• The neuronal processes that leave the nucleus pass around the
abducens nucleus before emerging the brain stem.
• There are four nuclei which contribute to the facial nerve :
1. Brachial motor nucleus(motor)
2. Superior salivatory nucleus(parasympathetic)
3. Tractus solitaris nucleus(special sensory)
4. Spinal nucleus of trigeminal tract(general sensory)
20. INFRANUCLEAR PORTION OF THE FACIAL NERVE
• CEREBELLOPONTINE ANGLE:
• The facial nerve emerges from the brainstem with a more slender nerve,
THE NERVE OF WRISBERG OR NERVUS INTERMEDIUS.
• These nerves are void of epineurium covered by pia matter and bathed in
cerebrospinal fluid.
• The average distance between the point where the facial motor nerve and
nervus intermedius exit the brainstem to their entrance into the internal
auditory canal is 15.8mm.
• The facial nerve and nervus intermedius lie above and slightly anterior to
the vestibuloacoustic nerve.
22. NERVUS INTERMEDIUS OR NERVE OF WRISBERG
• The nerve lies between the motor nerve and the eight cranial
nerve in the cerebellopontine angle.
• This portion contains preganglionic parasympathetic fibers
destined for submandibular ganglion and parasympathetic fibers
for the sublingual and submandibular glands and for
sphenopalatine ganglion with postganglionic connections to the
glands of the palate, nasal mucosa and lacrimal glands and also
sensory fibres to the geniculate ganglion.
• Fibers for taste arising from tractus solitarius are also contained
within this root.
26. TRANSTEMPORAL BONE PORTION OF
THE FACIAL NERVE
• INTERNAL AUDITORY CANAL:
• Also known as the meatal
segment.(8-10 mm)
• The motor portion and the nervus
intermedius are loosely joined
together as they enter the internal
auditory meatus with the acoustic
nerve.
• The acoustic nerve lies inferiorly in
position with the facial nerve.
29. • At the fundus of the internal
meatus, a transverse ridge called
crista falciformis divides the
auditory meatus into superior and
inferior compartments.
• The facial nerve passes across the
top of this ledge and is separated
from the superior vestibular nerve
by a vertical bony ridge referred to
as Bill’s bar.
• At this point it enters the fallopian
canal
BILLS
BAR
TRANSVERSE
CREST
NERVE VII
30. FALLOPIAN CANAL
• The course of the facial nerve through the fallopian canal
is unique.
• The nerve is also remarkable for the z shape of its
intratemporal portion in that it has a ganglion and that the
length of its course is 28mm to 30mm.
• It has three segments
1. Labyrinthine segment
2. Tympanic segment[horizontal]
3. Mastoid segment[vertical]
31.
32.
33. LABYRINTHINE SEGMENT
• The labyrinthine segment of the facial nerve lies beneath the
middle fossa and its shortest [3-5mm] and thinnest segment of the
facial nerve within the fallopian canal.
• It extends from the fundus of the internal auditory canal to the
distal portion of the geniculate ganglion.
• The term labyrinthine is fiting for this portion of the canal because
the cochlea is just anterior to the nerve and posteriorly and
laterally lie the ampullated ends of the horizontal and superior
semi-circular canals.
• The nerve rests on the anterior part of the vestibule.
34. • The labyrinthine segment of the facial nerve includes the geniculate
ganglion from which arises the first branch of the facial nerve ,the
GREATER PETROSAL NERVE.
• This nerve carries secretory motor fibers to the lacrimal gland.
• The second branch from the geniculate ganglion, the EXTERNAL
PETROSAL NERVE , is an inconstant tiny thread that carries sympathetic
fibres to the middle meningeal artery
• The third branch is the LESSER PETROSAL NERVE, which is joined by the
fibers of the tympanic plexus, contributed by the ninth nerve.
• This nerve carries secretory fibres to the parotid gland.
• The contributions to this nerve from the nervus intermedius provides an
alternate route for parasympathetic fibres to reach the parotid, thus
bypassing the tympanic plexus and the ninth cranial nerve branch of
Jacobson.
37. GENICULATE GANGLION
• The geniculate ganglion marks the sudden, acute change of direction taken
by the facial nerve at its first genu within the temporal bone.
• Upon surgical exposure, the geniculate ganglion appears pinkish because of
the rich blood supply within it , compared with the luminous or glassy
appearance of other portion of the nerve.
• The geniculate ganglion is an L-shaped collection of fibers and sensory
neurons of the facial nerve located in the facial canal of the head. It receives
fibers from the motor, sensory, and parasympathetic components of the
facial nerve and sends fibers that will innervate the lacrimal
glands, submandibular glands, sublingual
glands, tongue, palate, pharynx, external auditory meatus and taste
sensations from the tongue.
39. VIDIAN NERVE
• The NERVE OF THE PTERYGOID CANAL (Vidian nerve) is formed by
the junction of the greater petrosal nerve and the deep petrosal nerve
within the pterygoid canal containing the cartilaginous substance ,
which fills the foramen lacerum.
• Course: It passes forward through the pterygoid canal with its
corresponding artery (artery of the pterygoid canal).
• It then enters the pterygopalatine fossa and joins the posterior angle
of the pterygopalatine ganglion.
41. PTERYGOPALATINE GANGLION
• Parasympathetic preganglionic
fibers from the facial nerve
(contained within the greater
petrosal nerve) synapse in
pterygopalatine ganglion.
PTERYGOPALATINE
FOSSSA
42.
43.
44.
45. TYMPANIC SEGMENT
• At the geniculate ganglion, the facial nerve makes a sharp angled turn
backward, forming a knee or genu to enter the tympanic portion of
the fallopian canal.
• The proximal end of the tympanic portion is marked by the geniculate
ganglion ,from which point the facial nerve courses distally 3 – 5 mm
passing just behind the cochleariform process and the tensor tympani
tendon.
• The entire tympanic segment is approximately 8-11mm long.
• The distal aspect emerges distal to the pyramidal eminence where the
fallopian aqeueduct forms the second genu.
• The surgeon can encounter ‘sentinel bleeding’ as the bone is thinned
and sheath exposed at the second genu. This sign is also encountered
at the stylomastoid foramen.
46. MASTOID SEGMENT
• The second genu is the beginning of the mastoid segment where it
continues vertically downward over the anterior wall of the mastoid
process to the stylomastoid foramen.
• The branches to this segment are:
1. The nerve to the stapedius
2. The chorda tympani
3. The nerve from the auricular branch of the vagus (arnolds nerve)
49. CHORDA TYMPANI NERVE
• This is the terminal branch of the nervus intermedius and usually arises
from the distal third of the mastoid segment.
• It runs upwards and anteriorly over the incus and under the malleus.
• The nerve crosses the tympanic cavity and exits the temporal bone
through the petrotympanic fissure(canal of hugier) to join the lingual
nerve.
• The nerve contains secretomotor fibers to the submaxillary and
sublingual glands .
• It also carries taste sensations from the anterior two third of the tongue
and fibres from the posterior wall of external auditory meatus.
53. EXTRACRANIAL SEGMENT OF THE
FACIAL NERVE
• The facial nerve leaves the facial canal at the stylomastoid
foramen.
• In the region just distal to the stylomastoid foramen there
are branches from the occipital artery and venous plexus
that pass lateral to the facial nerve.
• Before the nerve bifurcates , nerve branches to the
POSTERIOR BELLY OF DIGASTRIC, STYLOHYOID and
POSTAURICULAR MUSCLES are given off.
54. • The facial nerve passes anterior to the posterior belly of
digastric muscle , lateral to the styloid process, external
carotid artery and posterior facial vein, and runs anteriorly for
2 cms before bifurcating into an upper and lower division.
• Both the branches run through the substance of the parotid
usually passing over the externtal jugular vein.
• The facial nerve is invariably found at a point where the tip of
the mastoid process, cartliginous auditory canal, border of
posterior belly of digastric meet.
55. As the facial nerve emerges
from the parotid gland on its
way to the facial muscles,
there is intermingling of
nerve filaments. This rich
plexus or network of nerve
fibres forms in the zone
between the parotid and
facial muscles.
PES ANSERINUS AND
BEYOND
58. ANATOMICAL RELATIONS OF THE FACIAL NERVE
• The facial nerve innervates 23 paired muscles and orbicularis oris.
• Freilinger divides these muscles into four layers
1. Most superficial: depressor anguli oris, zygomaticus minor, orbicularis
oculi
2. Second layer: depressor labii inferioris, platysma, zygomaticus major,
levator labii superioris
3. Third layer : orbicularis oris
4. Deepest layer: mentalis, levator anguli oris, buccinator
• The muscles from the first three layers are supplied by the nerve from the
deep surface and the fourth layer muscles are supplied from their lateral or
superior surface.
66. TASTE
TASTE TEST
• Drop of sugar or salt on one side of
protruded tongue or electro-gustometer.
• Ageusia or atrophied papillae
injury to chorda tympani nerve.
67. SCHRIMER’S TEST
• It compares lacrimation of both sides using a strip of filter paper
hooked in the lower fornix of the eye
• Decreased lacrimation lesion proximal to geniculate
ganglion
TEARING
68. SALIVATION
SUBMANDIBULAR SALIVARY FLOW TEST
• This measures functions of chorda tympani
• Polythene tubes are passed into both Wharton
ducts and drops of saliva are measured during
one minute period.
• Decreased salivation injury to chorda
tympani
69. STAPEDIAL REFLEX
TYMPANOMETRY
• Absence of stapedial reflex when hearing is
normal indicates a lesion of the facial nerve
proximal to the nerve to the stapedius.
70. CORNEAL BLINK REFLEX
• Mediated by sensory fibers of the trigeminal nerve
and motor fibers of the facial nerve
• Bilateral blink reflex when cornea of one eye is
touched with a wisp of cotton
• Which is known as consensual reflex
• If the depression of the reflex were secondary to
seventh nerve hypofunction, only direct response
would be depressed, consensual reflex will remain
intact.
72. GRADING OF RECOVERY FROM FACIAL
NERVE PARALYSIS (HOUSE BRACKMANN)
GRADE I NORMAL
GRADE 11 MILD DYSFUNCTION
GRADE 111 MODERATE DYSFUNCTION
GRADE IV MODERATELY SEVERE DYSFUNCTION
GRADE V SEVERE DYSFUNCTION
GRADE VI TOTAL PARALYSIS
75. J Oral Maxillofac Surg. 2016 May;74(5):1013-22. doi: 10.1016/j.joms.2015.12.013. Epub 2016 Jan 7.
A Modified Preauricular Approach for Treating Intracapsular Condylar
Fractures to Prevent Facial Nerve Injury: The Supratemporalis
Approach.
Li H1, Zhang G2, Cui J3, Liu W1, Dilxat D1, Liu L4.
Author information
1
Resident, Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
2
Associate Professor, Department of Stomatology, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
3
Attending Staff, Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
4
Professor, Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China. Electronic address: drliulei@163.com.
79. ETIOLOGY
The viruses/bacteria that have been linked to the
development of Bell’s palsy include:
• Herpes simplex, which causes cold sores and
genital herpes
• HIV, which damages the immune system
• sarcoidosis, which causes organ inflammation
• Herpes zoster virus, which
causes chickenpox and shingles
• Epstein-Barr virus, which causes mononucleosis
• Lyme disease, which is a bacterial infection caused
by infected ticks
80. • corticosteroid drugs, which reduces inflammation
• antiviral or antibacterial medication, which may be prescribed if a virus or
bacteria caused your Bell’s palsy
• over-the-counter pain medications, such as ibuprofen or acetaminophen,
which can help relieve mild pain
• eye drops
• an eye patch (for your dry eye)
• a warm, moist towel over your face to relieve pain
• facial massage
• physical therapy exercises to stimulate your facial muscles
• Surgical treatment
• Surgical nerve decompression
MEDICATION
HOME TREATMENT
SURGICAL TREATMENT
83. SURGICAL LANDMARKS FOR
IDENTIFICATION
• Tympanomastoid suture : The facial nerve and chorda tympani lie deep to
this suture, but this landmark is not of much importance as it is not
palpable.
• Digastric muscle :Nerve is immediately superior to digastric
• Tragal pointer: The facial nerve trunk is commonly found 1 cm inferior and 1
cm deep to the tragal pointer. This is termed as Conley’s pointer. This
relationship may be altered by the presence of tumor, previous surgery, or
infection.
• Styloid process :The facial nerve is located in the angle between the styloid
process and the posterior belly of the digastric muscle. The nerve crosses
the styloid process more anteriorly.
84.
85.
86. SURGICAL LANDMARKS FOR
IDENTIFICATION
• Tympanomastoid suture : The facial nerve and chorda tympani lie deep to
this suture, but this landmark is not of much importance as it is not
palpable.
• Digastric muscle :Nerve is immediately superior to digastric
• Tragal pointer: The facial nerve trunk is commonly found 1 cm inferior and 1
cm deep to the tragal pointer. This is termed as Conley’s pointer. This
relationship may be altered by the presence of tumor, previous surgery, or
infection.
• Styloid process :The facial nerve is located in the angle between the styloid
process and the posterior belly of the digastric muscle. The nerve crosses
the styloid process more anteriorly.
87. • If the proximal segment of facial nerve
is obscured, retrograde dissection of 1
or more of the peripheral branches
may be necessary to identify the main
trunk.
• Ramus frontalis is located by a line
from tragus to lateral canthus.
• Ramus buccalis is located by a line
from the tragus towards alae of the
nose parallel to the zygoma but 1 cm
below.
• Ramus mandibularis is near the angle
of mandible at a point 4-4.5 cm from
the attachment of the lobule of pinna.
88. MARGINAL MANDIBULAR NERVE
The distance of the marginal mandibular branch of the facial nerve from the
inferior border of the mandible from 1.4 to 1.75 cm.
The marginal mandibular branch of the facial nerve must be looked for in
all operative procedure near the angle of the mandible to a distance of 1.5
cm below the lower margin of the mandible.
Therefore, in order to avoid damage to the nerve in the submandibular
region, the incision should be made 1.5 cm or more below the lower border
of the mandible.
By giving an incision of two fingers breadth below and parallel to the angle
of the mandible, the marginal mandibular branch of the facial nerve can be
isolated in the upper flap.
91. RAMSAY HUNT SYNDROME
• Ramsay Hunt syndrome is defined as
an acute peripheral facial neuropathy
associated with erythematous vesicular
rash of the skin of the ear canal,
auricle (also termed herpes zoster
oticus), and/or mucous membrane of
the oropharynx, facial paralysis and
ear pain.
• This syndrome is also known as
geniculate neuralgia or nervus
intermedius neuralgia.
92. CONCLUSION
• An intimate knowledge of facial nerve anatomy is critical to avoid its
inadvertent injury during parotidectomy, maxillofacial fracture
reduction, and almost any surgery of the head and neck.
• Injury to the frontal and marginal mandibular branches of the facial
nerve in particular can lead to obvious clinical deficits, and areas
where these nerves are particularly susceptible to injury have been
designated danger zones.
• The constellation of deficits resulting from facial nerve injury is
correlated with its complex anatomy to help establish the level of
injury, predict recovery, and guide surgical management.
