Anatomy of Facial Nerve, Facial Nerve Anatomy. Hope it will be helpful for you. Regards, Dr Diptiman Baliarsingh +919438436775

1. DR. DIPTIMAN BALIARSINGH
1st Year PG (ENT),HMCH.

2. Introduction :
 VII Cranial Nerve - Mixed N
 10,000 Motor , Sensory , parasympathetic fibers
 Motor root – 7000 special visceral efferent fibers
 Sensory & Parasympathetic – 3000 fibers carried by
“NERVUS INTERMEDIUS” (Nerve of Wrisberg)

3. Structure of nerve :
 From inside out Nerve fibre consists of axon, myelin
sheath, neurilemma & endoneurium
 A group of nerve fibre is enclosed in a sheath called
perineurium to form a fascicle
 The fascicles are bound together by epineurium

4. Components of a Nerve :
 Endonerium
 Surrounds each nerve fiber
 Provides endoneural tube for regeneration
 Much poorer prognosis if disrupted
 Perinerium
 Surrounds a group of nerve fibers
 Provides tensile strength
 Protects nerve from infection
 Pressure regulation
 Epinerium
 Surrounds the entire nerve
 Provides nutrition to nerve

5. Nerve Structure

6. Facial Nerve Nuclei :
 Facial Nerve has 3 nuclei
 Motor nucleus – lower pons below 4 th ventricle
 Superior salivatory nucleus – dorsal to motor N
 Nucleus of tractus solitarius – medulla oblongata

8. Facial Nerve and Central connections

9. Facial nerve: Types of fibers
 Special Visceral Efferent/Branchial Motor
 General Visceral Efferent/Parasympathetic
 General Sensory Afferent/Sensory
 Special Visceral Afferent/Taste

10. Special Visceral Efferent/Branchial Motor :
 Premotor cortex 
Motor cortex 
Corticobulbar tract 
bilateral facial motor nuclei (pons) 
facial muscles
• Stapedius
• Stylohyoid
• Posterior belly of Digastric
• Buccinator

11. General Visceral Efferent/Parasymp.:
 Superior salivatory nucleus (pons)  nervus intermedius 
greater/superficial petrosal nerve 
facial hiatus/middle cranial fossa 
joins deep petrosal nerve (symp fibers 4m cerv. plexus) 
passes through pterygoid canal (as Vidian nerve) 
pterygopalatine fossa  spheno/pterygopalatine gang. 
postganglionic parasympathetic fibers 
joins zygomaticotemporal nerve(V2) 
lacrimal gl. & seromucinous gl. of nasal & oral cavity.

12.  Superior salivatory nucleus  nervus intermedius 
chorda tympani nerve  joins lingual nerve 
submandibular ganglion 
postganglioic parasympathteic fibers 
submandibular and sublingual glands.

13. General Sensory Afferent/Sensory:
 Sensation to auricular concha , EAC wall, part of TM,
postauricular skin
 Cell bodies in geniculate ganglion
Special Visceral Afferent/Taste:
 Postcentral gyrus  nucleus solitarius 
tractus solitarius  nervus intermedius 
geniculate ganglion  chorda tympani 
joins lingual nerve  anterior 2/3 tongue, soft
and hard palate

14. Distribution of
FACIAL NERVE
fibers

15. Central Connections of FN Nucleus
 Upper part of Nucleus – B/L supranuclear (cortical)
innervation
 Lower part of Nucleus– C/L supranuclear innervation
 Imp – function of forehead preserved in supranuclear
lesions

17. DIVISIONS OF FACIAL NERVE
 Divided into 3 parts:-
 Intracranial
 Intratemporal
 Extracranial

18. Intracranial Course:
 length 23-24mm
 Motor fibers hook around Nucleus of VI CN and joins the
Sensory root (N of Wrisberg)
 FN (+ VC N + Abdu N) leaves brainstem at Ponto-medullary
junction
 F N passes through CP angle with VC N & Nervus Intermedius
 At the fundus of IAC, FN enters fallopian canal
 Devoid of epineurium - thin layer of pia mater surrounds it and
continues into the meatal segment
 Surg imp :
 Iatrogenic trauma in CP angle tumour surgery
 Difficult to identify in schwannoma (no connective tissue)

21. Intra Temporal Course:
 From IAC to SMF
 Length – 28 to 30 mm
 Longest bony canal
 3 segments by 2 genus

22. Intra Temporal Course of Facial Nerve

23. Intra Temporal Course of Facial Nerve

24. Intratemporal Course of Facial Nerve

25.  Meatal Segment
 Lies in IAC
 Enters in ant. sup. segment of IAC
 Length 5 – 12 mm
 No separate sheath
 Shares with NI & VIII CN
 Baths in CSF

26. Relation of N fibres in IAC

27. *Bill’s Bar & Falciform Crescent
 Bill's bar was named after Dr William House
 It divides the superior compartment of the internal acoustic meatus
into an anterior and posterior compartment.
 Anterior to Bill's bar, in the anterior superior quadrant are the facial
nerve (CN VII) and nervus intermedius
 Posterior to it in the posterior superior quadrant is the superior division
of the vestibular nerve
 The falciformcrescent is a horizontal ridge that divides the internal
acoustic meatus into superior and inferior portions.
 Superior - The facial nerve and superior vestibular nerve (SVN) travel
in the superior portion of the IAM with the facial nerve anterior to the
SVN and separated from it in the lateral portion by Bill's bar, a vertical
ridge of bone.
 Inferior - The cochlear nerve and inferior vestibular nerve (IVN) run
inferior to the falciform crescent with the cochlear nerve situated more
anteriorly.

28.  Labyrinthine Segment
 Narrowest(0.68mm) & Shortest(3-5mm)
 From Meatal foramen to Geniculate Ganglion (1st Genu)
 No anastomosing arteries
 Periostium is thicker
 Relations :- the segment is
 Posterocephald (Posterosuperior) to cochlea
 Anteromedial to Sup SCC
 Cephald (Superior) to vestibule
 Continuation of Internal auditory canal

29.  Surgical importance:
 Anatomical “bottle neck” – ischemia in oedema resulting in
BELL’S PALSY, Part most vulnerable for ischemia (no arterial
anastomosis & surrounded by dense arachniod band)
 Temporal bone # - MC injured
 Geniculate ganglion :(distal end)
 Bipolar ganglion cells - Afferent input pain & taste fibres
 Secretomotor fiber to lacrimal gland by GSPN

30.  Tympanic Segment
 From Geniculate ganglion to 2nd genu
 Length – 8 to 11 mm
 Lies beneath LSCC & above OW
 At its proximal end above & medial to Processus
cochleariformis & TT muscle.
 Creates 2 recesses
 Facial recess (lat)
 Sinus tympani(med)

31. Facial recess and sinus tympani relations with facial
nerve and pyramidal eminence

32.  Surgical importance:
 Processus cochleariformis (consistant landmark)
 Imp landmark for 2 nd genu
 Hug the inf. LSCC
 Pyramidal eminence
 B/w short process of incus(L) & Lat SCC(M)

33.  Mastoid Segment
 From 2 nd genu (PM) to SMF(AL)
 Longest (13mm)
 Landmark – “ Digastric Ridge” identified by medial
aspect of mastoid tip
 FN leaves FC via SMF (b/w mastoid tip & styloid
process)
 Has 3 brances
 Chorda Tympani
 N to stapedius
 sensory auricular branch

34. Review of the Intra Temporal part of Facial
Nerve, its branches and communications

35. Facial Nerve course in relation to Middle Ear
(Lateral View)

36. Facial Nerve course in relation to Middle Ear
(Medial View)

37. Facial Nerve Course in the medial wall of middle ear

38. Nerves in relation with the middle ear

39. Extra Cranial Course
 From SMF to Terminal branches
 Runs in substance of parotid
 Main trunk divides forming “Pes anserinus”
 upper temperofacial
 lower cervicofacial
 Superficial to Retromandibular vein & Ext. carotid art

40. Course of Facial Nerve in Parotid Gland
(Transverse Section)

42. Branches of Facial N:
 Intra temporal region :
 GSPN
 N to Stapedius
 Chorda Tympani
 Sensory Auricular branch
 Extra temporal region
 Posterior Auricular Nerve
 Muscular branches
 Stylohyoid
 Post. belly of Diagastric
 Terminal Branches
 Temporal
 Zygomatic
 Buccal
 Marginal Mandibular
 Cervical

43. Intra temporal region:
 GSPN:
 From Geniculate ganglion 2 types of fibers arise
 Preganglionic parasympathetic 
Pterygopalatine gang.  Postganglionic  lacrimal gland
 Sensory fibers to nasal & palatine glands 
joins Deep Petrosal N  N of pterygoid canal
 Nerve to Stapedius:
 6mm above SMF
 Supply - Stapedius

44.  Sensory Auricular Br:
 Joins auricular br of vagus
 Supply retro-auricular groove & concha
 Chorda tympani Br:
 4-5mm above SMF
 Lat & ant to Facial N
 Passes b/w long process incus & upper part of handle of
malleus
 2 types of fibers
 Preganglionic parasympathetic  Submandibular Ganglion
 Postganglionic  submandibular & sublingual gland
 Special sensory  ant 2/3 rd of tongue

45. Surgical importance:
 GSPN - landmark in middle cranial fossa approach
 CT – landmark in posterior tympanotomy
 CT – lateral margin of facial recess
 CT – medial limit for facial ridge in CWD

46. Extratemporal region:
 The stylomastoid foramen 
medial aspect of mastoid tip 
FN exit from Stylomastoid Foramen 
below tympanic plate & Lat to the base of styloid 
nonvascular area Lateral to base of carotid sheath &
behind the parotid gland
 Post. Auricular N
 Muscles of pinna
 Occipitofrontalis
 Muscular Branches
 Post. belly of digastric
 Stylohyoid

47. Terminal branches :
 Temporal :
 Comes out through the upper pole of parotid gland
 Cross zygomatic arch
 Muscles supplied
 Auricularis anterior & superior
 Frontalis
 Corrugator supercilii
 Procerus
 Upper orbicularis oculi
 Action – Raising eyebrows

48.  Zygomatic :
 Also called Upper Zygomatic
 Cross zygomatic bone
 Muscles supplied
 Lower Orbicularis oculi
 Action – Tight shutting of eye

49.  Buccal :
 1 cm below zygomatic arch
 2 in number -Upper deep buccal & Lower deep buccal
 runs along parotid duct
 Muscles supplied :-
 Risorius (smirk)
 Buccinator (aids chewing)
 Levator Labii Superioris Alaque Nasi (snarl)
 Levator Anguli Oris (soft smile)
 Nasalis (Flare Nostrils)
 Upper Orbicularis Oris
 Action – Showing Teeth

50.  Marginal Mandibular(RamusMandibularis) :
 Comes out through the ant. border of parotid gland
 Runs 1-2cm below the ramus of mandible inferiorly
 Supplies muscles of lower lip & chin
 Lower Orbicularis Oris
 Deperessor anguli oris
 Depressor labii inferioris
 Mentalis
 Actions – Whistle & Puckering of Lips

51.  Cervical :
 Comes out through the lower pole of parotid gl.
 Muscle Supplied – Platysma
 Action – Contraction of Platysma

53. Terminal branches of Facial Nerve

54. Pattern of branching of Terminal branches of Facial Nerve
(Classification & Branching pattern by Davis et al - Gray’s ANATOMY)

55. Katz & Catalano classification:
 Type I (25%)no anastomic links bet the 2 branches
 Type II (14%) buccal branch subdivided
 Type III(44%)
 Type IV(14%)
 Type V(3%)

56. Anatomical Relationship of FN in Adults & Children:
Child
• Absent mastoid
process & incomplete
tympanic ring. CT
may exit thru SMF
• 2nd genu is more
acute & lateral
• N trunk on exit from
SMF is more anterior
& lateral
• N very superficial
over angle of
mandible
Adult
• Mastoid process &
complete ring . CT
exits separately prox
to SMF
• 2nd genu less acute
& more medial
• Parotid is more post.
N trunk is less
anterior & deeper
• N superficial over
angle of mandible

57. Blood Supply :
 Ant. Inf. Cerebellar Art.  Supply nerve in CP angle
 Intracranial/Meatal  Labyrinthine branches from
AICA
 Geniculate & Peri-geniculate  Superficial Petrosal
branch of Middle Meningeal Artery
 Tympanic/Mastoid  Stylomastoid branch of
Posterior Auricular Artery

58. Facial Nerve embryonic development:
 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 FN tissue is seen at the 3rd week
of gestation- facioacoustic primordium or crest

59.  Facial nerve embryology - 4th week
 By the end of the 4 th week, the facial and acoustic
portions are more distinct
 The facial portion extends to placode
 The acoustic portion terminates on otocyst
 Facial nerve embryology - 7th week
 Early 7 th 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

60. Facial nerve embryonic development:
 Extratemporal segment – FN branches:
 Proximal branches form - First 6th week,
 Posterior auricular branch > branch of digastric - Early 8th week,
 Temporofacial and Cervicofacial divisions - Late 8 th week (5 major
peripheral subdivisions present)
 Extratemporal segment – other nerves :
 Facial nerve communicates with
 peripheral branches of CN V, IX, X,
 cervical cutaneous nerves
 greater auricular nerve
 transverse cervical branches of the cervical plexus (C2, C3)
 Trigeminal nerve: auriculotemporal , infraorbital , buccal , mental
branches
 All connections are complete by week 12, except for connections to
branches of CN V at orbit periphery - these are completed at 4.5
months

61. Surgical Landmarks :
 Ear & Mastoid surgery
 Geniculate ganglion lies behind & superior to Processus
cochleariformis
 2nd genu hugs inferior aspect of LSCC
 Facial N lies above OW niche
 Incus lies lateral to Facial N
 Facial N runs behind Pyramid
 Facial N lies 6-8mm inferior to Tympano-mastoid suture
 Digastric ridge – mastoid segment
 Parotid surgery
 Tragal pointer – Fn lies 1cm deep to it
 FN lies 1cm inferior to Tympanomastoid suture
 N bisects angle b/w Post belly of digastric & ear canal
 Buccal br 1 cm below & parallel to zygomatic arch
 N lies lateral to Styloid process & Superficial to Retromandibular vein

62. Variations:
 MC variations
 Facial N displacements
 Dehiscence of fallopian canal 50% -MC
 Dehiscence in tympanic/horizontal seg (91%)
 Vertical seg. variations
 Bifurcation/ Trifurcation of the N
 Ant displaced N With post hump

63. THANK YOU… 
 REFERENCES:-
 GRAY’s Anatomy - 29th Edition
 Scott Brown’s Otorhinolaryngology & Head and Neck Surgery – 7th Edition
 Cumming’s Otolaryngology & Head and Neck Surgery -5th Edition
 Glasscock-Shambaugh Surg. of EAR – 6th Edition
 Mohan Bansal – 2nd Edition
 BD Chaurasia’s – Human Anatomy 3rd Edition