1. Anatomy of Facial NerveAnatomy of Facial Nerve
Presented by Dr. Ketaki Pawar.
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2. Table of contents
• Introduction
• Surface marking
• Functional components
• Nuclei
• Course and relations
• Branches and distribution
• Ganglia
• Clinical anatomy
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3. Introduction
• Seventh cranial nerve
• 2nd
only to vagus as the “busiest” cranial nerve of
the human body
• Nerve of the second branchial arch
• The facial nerve consists of the facial nerve
proper and the intermedius nerve.
• Both the facial nerve proper and the intermedius
nerve emerge from the CNS in the
cerebellopontine angle at the caudal border of
the pons, between the abducens nerve and the
vestibulocochlear nerve .
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4. Surface markings
• Marked by a short
horizontal line which
joins following two
points:
1)A point at the middle
of the anterior border
of the mastoid process.
2)Behind the neck of the
mandible.
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5. Functional components
1. Special visceral or branchial efferent, to
muscles responsible for facial expression,
posterior belly of digastric muscle , stylohyoid
and stapedius
2. General visceral efferent or
parasympathetic:
These fibers are secretomotor to the
submandibular and sublingual salivary glands,
the lacrimal gland, and glands of the nose,
the palate and the pharynx.
3. General visceral afferent : carries afferent
impulses from the above mentioned glands.
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6. 4. Special visceral afferent fibres carry taste sensations
from the anterior two thirds of the tongue except
from vallate papillae and from the palate.
5. General somatic afferent fibres innervate a part of
skin of the ear .
Brachial motor- largest portion
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8. Nuclei
• The fibres of the nerve arise from four nuclei
situated in the lower pons.
1.Motor nucleus or brachiomotor : lies deep in
the reticular formation of the lower pons.
2.Superior salivatory nucleus or
parasympathetic.
3.Lacrimatory nucleus – parasympathetic.
4.Nucleus of tractus solitarius – gustatory and
also receives afferent fibres from the glands.
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9. Supranuclear
anatomy
• Cortex and internal capsule:
Voluntary responses of the facial
muscles arises from efferent
discharge from motor face area
of the cerebral cortex.
• The motor face area is situated
on the pre central and post central
gyrus.
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•Discharges from the facial motor
area are carried through fascicles
of the corticobulbar tract to the
internal capsule, then through the
upper midbrain to the lower
brainstem, where they synapse in
the facial nerve nucleus located in
pons.
•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 lower face are
crossed only once.
Posterior view of the brainstem
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Contents of right internal auditory canal
•Facial nerve emerges from
the brainstem with nervus
intermedius
•The average distance
between
the point where the nerves
exit the brainstem and the
place where they enter the
internal auditory canal is
approximately
15.8 mm
12. Intracranial course and relations
• Facial nerve is attached to the brainstem by two roots
: motor and sensory ( nervus intermedius) which are
attached to the lateral part of the lower border of
pons just medial to eight cranial nerve.
• The motor and sensory root runs laterally and
forwards, with the 8th
nerve to reach the internal
acoustic meatus. In the meatus the motor root lies in
a groove on the 8th
nerve with the sensory root
intervening.
• At the bottom of the meatus , the two roots fuse to
form a single trunk which lies in the petrous temporal
bone.
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Within the canal, the course of the nerve can be
divided into three parts by two bends:
1.First part is directed laterally above the vestibule.
2.Second part runs backwards in relation to the
medial wall of the middle ear, above the promontory.
3.Third part is directed vertically downwards behind
the promontory.
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• The first bend at the junction of first and second
part is sharp and it is called as genu.
• The second bend is gradual and lies between the
promontory and the aditus to the mastoid
antrum.
• Facial nerve leaves the skull by passing through
the stylomastoid foramen.
17. 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, runs forwards through the
gland crossing the retromandibular vein and
the external carotid artery.
• Behind the neck of the mandible it divides into
its five terminal branches which emerge along
the anterior border of parotid gland
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18. Branches and distribution
A. Within the facial canal:
1. Greater petrosal nerve
2. The nerve to the stapedius
3. Chorda tympani
B. At its exit from the stylomastoid foramen:
1. The posterior auricular
2. Digastric
3. Stylohyoid
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C. Terminal branches
within the parotid gland:
1.Temporal
2.Zygomatic
3.Buccal
4.Marginal mandibular
5.Cervical
D. Communicating
branches
with adjacent cranial and
Spinal nerves.
21. Greater Petrosal nerve
• Leaves at the genu
• pre ganglionic parasympathetic fibers
pterygopalatine ganglion lacrimal gland
• Leaves the facial canal through the hiatus, runs forwards,
downward and inward in a furrow on the anterior
surface of the pyramid of the temporal bone.
• Leaves the cranial cavity through foramen lacerum after
joining the deeo petrosal nerve from the sympathetic
plexus of the internal carotid artery
• Sup and deep petrosal nerves form the pterygoid or the
vidian nerve pterygopalatine ganglion
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22. Nerve to stapedius muscle
• Arises opp. to the pyramid of the middle ear
• Supplies the stapedius muscle
• Stapedius muscle – dampening of excessive
vibrations of the stapes
• In paralysis- hyperacusis
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23. Chorda tympani
• Arises 6 mm above stylomastoid foramen
• Contains taste fibers and preganglionic
parasympathetic secretory fibers
• Enters tympanic cavity posterior wall in close
relation to tympanic membrane Leaves the middle
ear by passing though petrotympanic fissure Enters
infratemporal fossa joins lingual nerve
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24. Posterior auricular
• Turns backwards and upwards between the
mastoid process and the auricle
• Supplies posterior auricular and occipital
muscles
Nerve to stylohyoid
• Supplies stylohyoid muscle
Digastric
• Supplies posterior belly of digastric
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25. Terminal branches
• At the stylomastoid foramen, the main trunk
enters the substance of the parotid gland.
• First separation into upper and lower division
usually occurs behind the mandible.
• The upper division- temporal, zygomatic and
upper buccal
• The lower division- lower buccal, mandibular
and cervical
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Temporal
• Emerge from the parotid gland at its upper pole
slightly in front of the superficial temporal artery
• Anterior temporal : frontalis, superior part of
orbicularis oculi, corrugator supercilii, procerus
• Posterior temporal : anterior and superior auricular
muscles
27. Zygomatic
• Leave the parotid gland on its anterosuperior
border
• Crosses the body of zygomatic bone
• Supply inferior part of orbicularis oculi
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28. Buccal
• Emerge at the anterior border of parotid
• Upper buccal: muscles of upper lip and the
muscles of the nose
• Lower buccal : buccinator and risorius
• Orbicularis oris
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29. Marginal mandibular
• Runs parallel to lower border of the mandible
• Cross facial vein and facial artery
• Supplies muscles of lower lip (depressor anguli
oris and depressor labii inferioris) and mental
muscles
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30. Cervical
• Leaves parotid gland at or slightly above its
inferior pole
• Runs downward and anteriorly
• Supplies platysma
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31. Communicating branches
• Facial nerve branches exchange fibers with
sensory cutaneous branches of the trigeminal
nerve.
• Connections between facial and trigeminal
branches results in formation of small mixed
terminal nerves, which carry motor and
sensory fibers to a limited area of the face
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Most important of these connections are:
• a branch of the auriculotemporal nerve joins the
upper branch of the facial nerve
•The upper buccal branches of the facial nerve join
branches of the infratemporal nerve in the canine fossa
•The cervical branch exchanges fibers with the
transverse colli nerve of the cervical plexus.
34. Ganglia
1. The geniculate ganglion is located on the first bend of
the facial nerve in relation to the medial wall of the
middle ear. It is a sensory ganglion. The taste fibres
present in the nerve are peripheral processes of
pseudounipolar neurons present in the geniculate
ganglion.
2. The submandibular ganglion is a parasympathetic
ganglion for relay of secretomotor fibre to the
submandibular and sublingual glands.
3. The pterygopalatine ganglion is also a
parasympathetic ganglion. Secretomotor fibres
present for the lacrimal gland relay in this ganglion.
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35. Vascular Supply
• Proximal and middle portions of the nerve via
the anterior inferior cerebellar artery and the
internal auditory artery respectively
• Further supply of middle portion of the nerve
comes from the petrosal artery via the middle
meningeal artery of the external carotid.
• Distal segment – by stylomastoid artery, also a
branch of external carotid artery
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36. References
• B.D. Chaurasia’s Human Anatomy- Vol 3
• Sicher And Dubrul’s Oral Anatomy
• RODRIGUES, Antonio de Castro et al. Anatomy of the
Facial Nerve and its Implication in the Surgical
Procedures. Int. J. Morphol. [online]. 2009, vol.27, n.1
• Gulam Hasan, Ashfaqul Hasan,Kulbeer Kaur, Muzaffar
Ahmad, Mohd. Shafi, The Facial Nerve : The
Anatomical and Surgical important,JK-
Practitioner2005;12(1):53-57
• Mark May , Barry M. Schaitkin The facial nerve 2nd
edition
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