The Facial nerve is the seventh cranial nerve that controls muscles of facial expression and conveys taste sensations from the tongue. It emerges from the brainstem between the pons and medulla. In the first three months of development, the facial nerve establishes its course through the facial canal and branching pattern. It has both motor and sensory functions and can be damaged, causing conditions like Bell's palsy or injuries during procedures near the parotid gland or temporomandibular joint.

2.  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
 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
Introduction

3. 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

4.  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

5. Nucleui of Origin
1.Motor nucleus of facial nerve (SVE
2. Superior salivatory nucleus (GVE)
3. Nucleus solitarus (SVA)
4. GSA fibers

6. Facial nerve origin

7. COURSE OF FACIAL NERVE
I- Intracranial (intrapetrosal) course
II- Extracranial course

8. 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.

10. 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.

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

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

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

15. 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.

16. 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

17. The temporal branches supply the auricularis anterior
and superior, and joining with the zygomaticotemporal
branch of the maxillary nerve, and with the
auriculotemporal branch of the mandibular nerve.
The more anterior branches supply the frontalis, the
orbicularis oculi, and corrugator supercilii, and join the
supraorbital and lacrimal branches of the ophthalmic.
TERMINAL BRANCHES

18. The zygomatic branches supply the Orbicularis oculi, and
join with filaments from the lacrimal nerve and the
zygomaticofacial branch of the maxillary nerve.
The Buccal Branches of the facial nerve (infraorbital
branches), pass horizontally forward to be distributed
below the orbit and around the mouth.
The marginal mandibular branch supplies the muscles of
the lower lip and chin, and communicating with the
mental branch of the inferior alveolar nerve.

20. Facial Nerve: Functional Components
 Special Visceral Efferent/Branchial Motor
 General Visceral Efferent/Parasympathetic
 General Sensory Afferent/Sensory
 Special Visceral Afferent/Taste

21. Special Visceral Efferent/Branchial Motor
 Premotor cortex  motor cortex 
corticobulbar tract  bilateral facial motor
nuclei (pons)  facial muscles
 Stapedius, stylohyoid, posterior digastric,
buccinators
 Lies in the lower part of pons

22. General Visceral Efferent/Parasympathetic
• It lies in the pons and gives rise to secretomotor
parasympathetic fibers that pass in greater
superficial petrosal nerve and chorda tympani.

23. Superior salivatory nucleus (pons)
nervus intermedius
greater/superficial petrosal nerve
facial hiatus/middle cranial fossa
joins deep petrosal nerve (symp fibers from cervical plexus)
through pterygoid canal (as vidian nerve)
pterygopalatine fossa
spheno/pterygopalatine ganglion
postganglionic parasympathetic fibers
joins zygomaticotemporal nerve(V2)
lacrimal gland & seromucinous glands of nasal and oral cavity

24. Superior salivatory nucleus
nervus intermedius
chorda tympani
joins lingual nerve
submandibular ganglion
postganglionic parasympathteic fibers
submandibular and sublingual glands

25. General Sensory Afferent/Sensory
Sensation to auricular concha, EAC wall, part of
TMJ, postauricular skin
Through Cell bodies in geniculate ganglion

26. Special Visceral Afferent/Taste
• It lies in the medulla, receives the taste
sensation from the anterior 2/3 of the tongue

27. Postcentral gyrus
nucleus tractus solitarius
nervus intermedius
geniculate ganglion
chorda tympani
joins lingual nerve
anterior 2/3 tongue, soft and hard palate

29. GANGLIAASSOCIATED
WITH THE FACIAL NERVE
Geniculate ganglion
Submandibular ganglion
Pterygopalatine ganglion

31. Clinical anatomy

32. Facial nerve paralysis
• Facial nerve paralysis is the most common complication in dental
practice
• Paralysis of some of its branches occur whenever an infraorbital
block/max. canine infiltration given
• Muscle droop is observed when the LA solution is deposited in
the deep lobe of the parotid gland, through which terminal
portions of the facial nerve extends, which is a transient condition
• Duration depends upon the duration of action of the LA solution
injected

33. Bell’s palsy
• Facial weakness
• Evidence for herpes simplex type 1 infection causing infranuclear
lesions
• Paralysis: Progresses to maximal deficit over 3 to 72 hours
• Pain (50%): Near mastoid process
• Hyperacusis
• Facial weakness
• Sensory loss is Mild or None

34. • Food accumulates between the teeth and cheek
• Labial articulation is impaired

35. Supra nuclear lesion
• Its usually a part of the hemiplegia
• Only the lower part of the opposite side of the face is paralysed
• The upper part with the frontalis and orbicularis occuli escapes
due to its bilateral representation in the cerebral cortex

36. VII disorders
Unilateral nerve paralysis
• Leprosy
• Lyme disease
• Neoplasm and masses
• Trauma
• Cardiofacial syndrome

37. VII disorders
Bilateral nerve paralysis
1. Melkersson syndrome
2. Möbius syndrome & Congenital facial paresis
3. Guillain barre disease
4. Leprosy
5. HIV infection
6. Myasthenia gravis

38. Parotid gland relation
• During the removal of parotid gland, the facial nerve is preserved
by removing the glands in two parts, superficial and deep
separately.
• The plane of cleavage is defined by tracing the nerve from
behind, forwards
• Mixed parotid tumour is a slowly growing parotid tumour which
doesn’t involve the facial nerve, but when it turns malignant, it
then involve the facial nerve

39. TMJ relation
• Temporal branches of the facial nerve is related to the lateral
aspect of the TMJ
• This leads to invariable damage to the facial nerve during surgical
correction of TMJ ankylosis
• This can mostly avoided by taking strict care during the
preocedure

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