Trigeminal nerve: its anatomy and clinical overview in ENT Focusing on Trigeminal neuralgia Herpes Zoster Ophthalmicus Frey's Syndrome

1. Presented by:
Dr. Lakshmi Unnikrishnan,
JR2, Dept of ENT, PMCH

2. OUTLINE
 Neuroanatomy of Trigeminal Nerve
 Course & distribution
 Clinical relevance
 Herpes Zoster Ophthalmicus
 Frey’s Syndrome
 Trigeminal neuralgia

3. TRIGEMINAL NERVE :
 Largest cranial nerve
 Arises from middle of lateral side of pons
 Passes forwards, laterally across subarachnoid space
 Large ganglion: over tip of petrous

5. Motor
nucleus
Chief
Sensory
Nucleus
Spinal
Nucleus
Mesencephalic
Nucleus
1st branchial
arch muscles
Touch
Pressure
Pain
Temperature
Proprioception
Sensory root
Motor root
Trigeminal
Ganglion
V3 V2
V1
Foramen
Ovale
Foramen
Rotundum SOF

7. MOTOR NUCLEUS OF TRIGEMINAL NERVE
 Fibres  Motor root of trigeminal nerve 
emerges on ventral aspect of pons, medial to the
sensory root.
 Motor root crosses the superior border of petrous
temporal bone and passes posterior to trigeminal
ganglion.
 Passes through Foramen Ovale  joins sensory
root of Mandibular Nerve

10. CHIEF SENSORY NUCLEUS OF TRIGEMINAL NERVE
 Concerned only with tactile sensibility.

11. SPINAL NUCLEUS OF TRIGEMINAL NERVE
 Concerned with the pain and temperature sensations.
 Based on the cytoarchitecture, three subnuclei:
In craniocaudal direction
 pars rostralis
 pars interpolaris
 pars caudalis

12.  The ascending fibres chief sensory nucleus.
 The descending fibres spinal tract of trigeminal nerve.
 Fibres of the spinal tract terminate in the subjacent spinal
nucleus.
 Chief sensory nucleus touch
 Spinal nucleus pain and temperature

13.  Spinal tract receives a small component of fibres from
the VIIth, IXth and Xth cranial nerves which carry
sensations from external ear, mucosa of posterior third
of tongue, pharynx and larynx.
Trigeminal
Lemniscus
Thalamus
(VPM)
Sensory
cortex

14. MESENCEPHALIC NUCLEUS OF TRIGEMINAL NERVE
 Made up of pseudounipolar cells (1st order sensory
neurons)
 Peripheral processes proprioceptive impulses from the
muscles of mastication, temporomandibular joint, teeth &
extrinsic muscles of tongue.

15.  Central processes  motor nuclei of trigeminal nerve of
the both sides.
 These connections establishes the stretch reflex
originating in neuromuscular spindles in masticatory
muscles + reflex for control of the force and accuracy of
bite.
 These reflexes prevent the tongue from being bitten
during chewing.
MESENCEPHALIC NUCLEUS OF TRIGEMINAL NERVE

17. Functional components in the three divisions
Division Functional components
Ophthalmic GSA fibres
Maxillary GSA fibres
Mandibular GSA and SVE fibres

18. COURSE AND DISTRIBUTION
Arises by two roots from pons at its junction with the
middle cerebellar peduncle.
 Large lateral sensory root
 Small medial motor root.
 Run forward and laterally over petrous apex to enter
middle cranial fossa. Here the sensory root exhibits an
enlargement—the trigeminal ganglion.
 Divides into: ophthalmic, maxillary and mandibular.

21. Lacrimal Nerve Frontal Nerve Nasociliary Nerve
Zygomaticotemporal Supratrochlear
Supraorbital
Superior Orbital Fissure
Ganglionic branch
Long ciliary branches
Posterior Ethmoidal Nerve
Anterior Ethmoidal Nerve
Infratrochlear Nerve
Internal Nasal External Nasal

22. OPHTHALMIC NERVE :
 1st division
 Lies below 6th Nerve in lateral wall of cavernous sinus :
Prone to damage
 Extensive sensory distribution:
Severe eye pain, forehead, nose, scalp, extending to vertex
 3 branches:
- Lacrimal Nerve
- Frontal Nerve
- Nasociliary Nerve

26. LACRIMAL NERVE:
 Runs along Lateral Rectus  lacrimal gland
  skin over lateral eyelid, brow
 Secretomotor fibres from zygomaticotemporal nerve
lacrimal gland
 Proprioceptive filaments from VII

27. FRONTAL NERVE
 Divides  supratrochlear, supraorbital nerve
  skin of forehead, scalp to vertex
 Prone to minor injuries over brow Causalgic syndrome

28. NASOCILIARY NERVE
 Important autonomic and cutaneous function
 Main trunk traverse orbit enters anterior ethmoid foramen
intracranial cavity
Runs forward across cribriform plate
Exits skull through a slit in crista galli nose
 mucosa of nasal cavity
Emerges at lower end of nasal bone
 skin: tip of nose, alar, vestibule

29. NASOCILIARY NERVE
In orbit,
 Branch Ciliary ganglion
 2 or 3 long ciliary nerves:
 carry pupillodilatory sympathetic fibres,
 convey corneal sensation (important)
 Behind anterior ethmoid foramen Infratrochlear branch
 lies on medial wall of orbit
  skin of upper medial eyelid, upper side of nose

30. CILIARY GANGLION

31. CORNEAL REFLEX
 Afferent limb via nasociliary nerve
 Efferent limb via VII
 Pointed wisp of cotton lower cornea
 Consensual reflex
 Even if VII paralysis, eyeball rolls up, discomfort felt,
opposite eyelid closes

33. CLINICAL SIGNIFICANCE
 Sensory root of 5th- sensitive to pressure & distortion
 Loss of corneal reflex: early sign of CP angle lesion

34.  Involvement of V1- painful, almost always +
extraocular nerve palsy
 lesions ~ cavernous sinus; malignancies orbit via
Inferior Orbital Fissure
CLINICAL SIGNIFICANCE

35. HERPES ZOSTER OPHTHALMICUS

36. HERPES ZOSTER OPHTHALMICUS
 Severe pain – V1
 Pain lasts between 4 & 5 days
 Vesicles: inner eyebrow on day 5 or 6 &
involve entire distribution of nerve branch

37.  D/D – Ruptured aneurysm,
Cranial arteritis,
Acute frontal sinusitis
 Severe chemosis- eye, extraocular nerve palsies
complicate picture
 Often vesicle appearance correct Dx

38. Middle Superior
Alveolar Nerve
Foramen rotundum
Pterygopalatine
fossa
Ganglionic branches
Zygomatic Nerve
Zygomaticotemporal
Zygomaticofacial
Posterior Superior
Alveolar Nerve
Infraorbital
canal
Anterior Superior
Alveolar Nerve
Infra orbital foramen
Palpebral branch
Nasal branch
Superior labial branch
DENTAL
PLEXUS

39. MAXILLARY NERVE :

40. MAXILLARY NERVE :
 skin of cheek, lateral nose, lateral part of ala, lower eyelid
 mucous membrane of cheek, upper lip

41. CLINICAL RELEVANCE
 Painless / painful loss of sensation over any part of face (V2) :
ominous
-Malignancy- antrum / nasopharynx
 Nasopharyngeal tumors-
-most commonly in fossa of Rossenmuller
-SCC

42. CLINICAL RELEVANCE
 Tumors- antrum / ethmoid- SCC / Adenocarcinoma
- 40% : present as neurological problem
- 70% : V involved
- 50% : III, IV, VI involved
- 8.5% : visual pathway affected
- 10% : lower cranial nerves affected
 Route of entry into skull : Inferior orbital fissure / Foramen
lacerum , alongside carotid artery

43.  V1 runs past mouth of eustachian tube & Fossa of
Rossenmuller
through orbital floor, just above antrum & onto face
 Surface branches of V1, V2- damaged
by blunt trauma: around orbit, cheek or
divided by lacerations
CLINICAL RELEVANCE

44. PTERYGOPALATINE GANGLION
 Main outflow: orbital, palatine, nasal, pharyngeal nerves
 mucous membranes of orbit, nasal passage, pharynx,
palate, upper gums
 Hay fever ganglion

47. VIDIAN NERVE

48. JNA

50. VIDIAN NEURECTOMY
For chronic rhinitis that is refractory to medical therapy, surgical intervention
such as endoscopic vidian neurectomy (VN) can be used to control the
intractable symptoms. Lasers can contribute to minimizing the invasiveness of
ENT surgery.

51. Intrasphenoidal vidian neurectomy in the diode laser-assisted group. (A)
Type 1 configuration of the vidian canal (arrows) is presented. (B–D) The
diode laser is used for cutting the vidian nerve (asterisk) without obvious
bleeding in a clear surgical field. IS, intrasinus septum.

52. Nerve to Medial Pterygoid
Buccal Nerve
Masseteric Nerve
Deep temporal Nerve
Nerve to lateral pterygoid
Auriculotemporal Nerve
Lingual Nerve
Inferior Alveolar Nerve

53. MANDIBULAR NERVE :

54. MUSCLES INNERVATED:
 Medial pterygoid
 Lateral pterygoid
 Temporalis
 Masseter
 Tensor tympani
 Tensor veli palatini
 Mylohyoid
 Anterior belly of digastric

55. AURICULOTEMPORAL NERVE
 Pass behind TMJ + VII  skin over tragus, helix, EAM,
TM
: via superficial temporal branch skin over temporalis
Referred otalgia
 Secretomotor fibres  parotid gland
& fibres from tympanic branch of IX via Otic ganglion

56. OTIC GANGLION

57. FREY’S SYNDROME

58. FREY’S SYNDROME
 Gustatory sweating
 After parotidectomy, trauma, surgery, inflammatory
injury of parotid, submandibular gland
 Postoperative incidence- 35-65%

60. PATHOPHYSIOLOGY
Aberrant cross innervation between
 post ganglionic secretomotor parasympathetic fibres to
parotid gland &
 post ganglionic sympathetic fibres to sweat glands of skin

62. Objective method of Dx: Minor startch- I test

63. RX
 Antiperspirant- Locally applied over involved skin
 1% glycopyrrolate roll on lotion
 Tympanic neurectomy
 Intracutaneous injection of botox A
 Thick skin flap, partial superficial parotidectomy
 Sternocleidomastoid muscle flap/ implantation material

64. LINGUAL N
 Sensations from presulcal tongue, floor of mouth,
lower gums
 Taste fibres of chorda tympani from mucous
membrane of anterior 2/3rd tongue
 Secretomotor fibres from submandibular ganglion
sublingual & anterior lingual gland
 + XII

66. Lingual nerve in the left lower third molar area (arrow)

71. Lingual nerve and submandibular duct

73. SUBMANDIBULAR GANGLION

74. SUBMANDIBULAR GANGLION

75. INFERIOR ALVEOLAR NERVE
 Enters mandibular canal –running forwards in mandible
 Re emerge on chin at mental foramen
 Divide incisive & mental branch
 Sensory fibres skin, mucous membrane: lower lip, jaw,
incisor, canine

76. MANDIBULAR NERVE :
Motor component of post trunk leaves inferior alveolar
nerve, just before entering mandibular canal
As Nerve to Mylohyoid mylohyoid, anterior belly of
digastric

77. CLINICAL RELEVANCE
 V3- involved in oropharyngeal, tonsillar &
mandibular tumors
 Painless numbness over chin, rather than pain

78. CENTRAL MECHANISM OF 5TH NERVE
 Jaw jerk: enhanced bilateral UMN lesion above midpontine
level

79. CENTRAL MECHANISM OF 5TH NERVE
 Decussation- fibres vulnerable: midline lesions (syringomyelia,
syringobulbia)
Classical sensory deficit (extend forwards from back of head)
Onion peel or balaclava sensory deficit
Leave sensation only over nose & central face (final stages of
development)

80. CLINICAL ASPECTS OF 5TH CRANIAL NERVE
 Damage- important to otolaryngologist
 Branches of Nerve & associated ganglia- oropharyngeal,
nasopharyngeal neoplasm
 Involvement of motor root: rare- remarkably resistant to
pressure / distortion
 If damaged: wasting of masseter- clenched teeth
 Pterygoids: attempted jaw opening against resistance
: jaw deviates to paralyzed side

81. CLINICAL ASPECTS OF 5TH CRANIAL NERVE
Paradox:
 Most common benign condition :- Trigeminal neuralgia
 exquisite facial pain
 Most serious conditions often quiet painless

82. CLINICAL ASPECTS OF 5TH CRANIAL NERVE
 Trigeminal sensory neuropathy- rare condition
 Painless numbness develops over 5th Nerve territory
 Starting in V2 bilateral

83. CLINICAL ASPECTS OF 5TH CRANIAL NERVE
 Rarely, extensive loss of sensation over face:
presenting symptom of vestibular schwannoma

84. TRIGEMINAL NEURALGIA

85. TRIGEMINAL NEURALGIA
o One of the most painful conditions
seen in Head & Neck region.
 Ageing changes in Nerve /
irritation by adjacent aberrant artery
 Anatomically precise distribution

86. TRIGEMINAL NEURALGIA
 Recurrent brief episodes- electric shock like pain
 Abrupt- onset & termination
 Pain- limited to > 1 division of V

87. At some point- triggered by: chewing, shaving, gentle breeze

88. TRIGEMINAL NEURALGIA
 F, >50 years- diagnosed
 Normal sensory function of V
 Clinical Dx

89. TRIGEMINAL NEURALGIA
MRI-
 rule out Multiple Sclerosis, AV malformation, CP angle
pathology (vestibular schwannoma, meningioma,
epidermoid)
 identify arterial compression of root entry zone- amenable to
neurosurgical decompession

91. TRIGEMINAL NEURALGIA
Rx
 Carbamazepine
 Baclofen, lamotrigine, pimozide
 Uncertain effect: botox,
clonazepam,
gabapentin,
phenytoin,
valproate

92. TRIGEMINAL NEURALGIA
Surgery:
 Microvascular decompression
 Ablative procedure: Radiosurgery
Peripheral neurectomy
Rhizotomy- various methods

93. MICROVASCULAR DECOMPRESSION
 Gently reroute blood vessel- compressing nerve- by
padding the vessel with a sponge
 1 inch opening made for craniotomy behind the ear
 Exposes V at its connection with the brainstem
 Nerve freed from compression
 Protected with a small teflon sponge

102. TRIGEMINAL NEURALGIA
Pain : 2 characteristic distribution:
 1st: runs from lower canine, along lower jaw just in front of
ear,
somtimes round into upper jaw (involving V3, V2)
 2nd less frequent type: runs from upper incisor or canine,
inside the nose and encircles the eye, involving V1 & V2.

103. Involvement of 2 divisions- make section of peripheral branch unsuccessful in long
term Management, but reduces triggering

104. TRIGEMINAL NEURALGIA
Transient sensory deficit- may follow a spasm of pain
Invalidate Dx
 Any evidence of sensory loss,
 Impaired corneal reflex or
 5th motor weakness
May complicate MS, rare as a presenting symptom