detailed anatomy of trigeminal nerve

1. Trigeminal Nerve
Seminar presented by:
Dr.Ambika Bhandari
1st year PG

2. contents
 Introduction
 Nerve root
 The sensory nuclei
 The gasserian ganglion
 The ophthalmic nerve
 The maxillary nerve
 The mandibular nerve
 Applied anatomy

3. THE TRIGEMINAL NERVE
 It is the Fifth and Largest Cranial nerve.
 Also called:
 Nerve Trigeminus
 Trifacial nerve
This nerve contains both motor and sensory fibers

4. Sensory supply to the scalp, teeth ,skin of
the face,forehead ,mucous membranes of
oral and nasal cavity,floor of the mouth
,teeth ,the anterior two third of tounge
and extensive portions of the cranial dura
Motor supply to muscles of the first
branchial arch
Propioceptive nerve fiber from masticatory
and facial muscles.

6. Nerve root
 It is attached to the ventral surface of
pons by a large sensory root and small
motor root.
 The two roots enter the middle cranial
fossa.
 The motor root lies ventro-medial to the
sensory root.

8. Sensory root
 These fibers arise from the posteromedial
margin of Semilunar Ganglion or the
gasserian ganglion.
 The ganglion forms central and peripheral
branches .
 The central branches are sensory roots of
trigeminal nerve and the periphral
branches form the ophthalmic ,maxillary
and mandibular nerve

9. The sensory root leaves the ganglion,
passes back and enter pons .
The fibers divide into ascending and
decending groups .
From here these fibers terminate into
different sensory nuclei of trigeminal
nerve.

10. ASCENDING FIBRES DESCENDING FIBRES
Terminate in UPPER sensory nucleus
In pons lateral to motor nucleus.
Terminate in SPINAL nucleus
extending caudally from
upper sensory nucleus to
2nd cervical segment.
Conveys::
· Light touch
· Tactile discrimination
· Sense of position
· Passive movement
Conveys::
Pain
Temperature
CENTRAL BRANCHES
(SENSORY ROOTS OF NERVE)

11. Motor Root
 The fibers of the motor root arise from
two nuclei, the superior and the inferior
motor nucleus located in upper pons.
 The motor root runs in front of and medial
to the sensory root, and passes beneath
the ganglion; it leaves the skull through
the foramen ovale, and, immediately
below this foramen, joins the mandibular
nerve.

13.  The fibers from the superior nucleus
constitute the mesencephalic root: they
descend through the mid-brain, and,
entering the pons, join with the fibers
from the lower nucleus, and the motor
root, thus formed, passes forward through
the pons to its point of emergence.
 It is uncertain whether the mesencephalic
root is motor or sensory.

14. The Sensory nuclei
 Sensory nuclei are arranged in 3 groups:
• Mesencephalic Nucleus
• Principal Sensory Nucleus
• Spinal Nucleus of 5th nerve

16. Mesencepalic nucleus
This nucleus serves as a sensory station that
recieves proprioceptive impulses from the
TMJ ,the periodontal ligament ,and the
hard palate
Also it recieves affrent impulses from the
stretch receptors of the muscles of
mastication ie these fibers are concerned
with perfect synchronization in controlling
the biting force

17. Principal sensory nucleus
Also called the main sensory or the upper
nucleus .
This nucleus gives rise to the dorsal
trigeminothalmic tract .
Sensory fibers from this tract ascend
upwards .

18. Spinal nucleus
this nucleus is also called the bulbospinal
nucleus.
Spinal nucleus extends from the main
sensory nucleus to the second cervical
segment
This gives rise to the ventral
trigeminothalmic tract

19. Gasserian Ganglion
 Also known as semilunar ganglion
 it is developed from the neural crest cells
 Contains unipolar neurons.
 Crescent shaped, with its convexity
directed forward and medially
 Located in Meckel's cavity in the upper
part of apex of petrous temporal bone.

21. Arterial supply of trigeminal ganglion
 by the ganglionic branches of
1. Internal carotid artery
2. Middle meningeal artey
3. Accesory meningeal artery

22.  The ganglion receives, on its medial side,
filaments from the sympathetic carotid
plexus .
 It gives off minute branches to the
tentorium cerebelli, and to the dura mater
in the middle fossa of the cranium.

24. Functional component of
trigeminal nerve
Special visceral effrent fibers
 They arise from the motor nucleus of
nerve and supply the muscles of
mastication
 Because they supply muscles developing
in branchial arch, so they are also known
as branchiomotor fibres

25. General somatic afferent fibers
These nerve fibres can be divided into 2
groups
1.Nerve fibres carrying sensation of
touch,pain,temperature from the skin of
face and mucous membrane of mouth and
nose
2.Another group of general somatic afferent
neurons carry proprioceptive impulses
from the muscles of mastication.

27.  From convex border of the trigeminal
ganglion three large nerves proceed, viz.,
the ophthalmic, maxillary, and
mandibular.
 The ophthalmic and maxillary consist
exclusively of sensory fibers; the
mandibular is joined outside the cranium
by the motor root.

28. Peripheral Branches
 Ophthalmic nerve
 Maxillary nerve
 Mandibular nerve

29. Ophthalmic Nerve
This is the first division of the trigeminal
nerve .
It is the smallest division of the trigeminal
nerve.
It is a pure sensory nerve.
Route:
Leaves from the upper part of the
Ganglion and passes forward through the
lateral wall of cavernous sinus , it enters
the orbit through the superior orbital
fissure, it divides into three branches.

30. Fibres are afferent to:
 In the middle cranial fossa the nervous
tentori branches supply the dura.
 Scalp
 Skin of forehead
 Conjunctiva of eyeball
 Lacrimal gland
 Skin of lateral angle of the eye
 Sclera of eyeball
 Lining of ethmoid cells

31. Subdivisions of Ophthalmic
Nerve:
 Lacrimal nerve
 Frontal nerve
 Nasociliary nerve

33. Lacrimal nerve
 it is the smallest of the three nerves
 It enters the orbit through the narrowest
part of the superior orbital fissure.
 In the orbit it runs along the upper border
of the lateral Rectus, with the lacrimal
artery, and communicates with the
zygomatic branch of the maxillary nerve.

34. SUPPLIES - Lacrimal Gland, Adjacent conjunctiva,
& lateral portion skin of the upper eyelid.

35. Frontal Nerve: (Largest of three)
 In middle of the orbit, nerve divides into:
Supra orbital nerve:
 Larger branch from supraorbital foramen
 Supplies middle portion of skin of upper
eyelid and skin of forehead & scalp
Supratrochlear Nerve:
 Smaller of the two
 Supplies the skin of the lower part of
forehead & medial portion of skin of upper
eyelid and conjunctiva.

36. Nasocilliary nerve
 this nerve is more deeply placed
 it passes through the anterior ethmoidal
foramen, front part of the cribriform plate
of the ethmoid bone, and runs down,
through a slit at the side of the crista galli,
into the nasal cavity.

37. NASOCILIARY
NERVE::
BRANCHES IN ORBIT:
· Long root of cilliary ganglion
· Long cilliary nerves:iris & cornea
· Posterior ethmoid nerve:post.
Ethmodal cell.
· Anterior ethmoid nerve
BRANCHES IN THE NASAL
CAVITY
Supplies the mucous
membrane of the cavity.
BRANCHES ON THE FACE:-
· Skin of medial part of both
eyelids
· skin over the side of bridge of
the nose.

39. MAXILLARY DIVISION
 2nd sensory division of the Trigeminal
nerve.

40.  Transmits afferent impulses from:
 Upper lip
 Lower eyelid
 Side of the nose
 Hard and soft palate
 Lining of maxillary sinus
 All maxillary teeth and gingiva
 Mucous membrane of most the nasal
cavity

41. Course
Intracranial part::
 Originates from the middle part of
semilunar ganglion
 Passes forward through the lateral wall of
cavernous sinus
 Exits through foramen rotundum.

42. Extracranial part::
 Enters pterygopalatine fossa.
 Enters inferior orbital fissure to enter
orbital cavity.
 Occupies infraorbital groove and enter
infra orbital canal.
 Emerges through infra orbital foramen.

44. MAXILLARY NERVE
In the Cranium
In the
Pterygopalatine
Fossa
In the Infra-
orbital Canal
On the Face
Middle meningeal
nerve
· Zygomatic.
· Sphenopalatine.
· Posterior superior
alveolar.
· Anterior superior
alveolar.
· Middle superior
alveolar.
· Inferior palpebral.
· External nasal.
· Superior labial
Lateral nasal
Superior labial

45. Middle meningeal nerve
 Travels with middle meningeal artery.
 it is given off from the maxillary nerve
directly after its origin from the semilunar
ganglion
 Sensory innervation to the duramater of
anterior half of middle cranial fossa.

46. Pterygopalatine branches
 2 short nerve twigs that unite at the
pterygopalatine ganglion.
 fibres pass through the ganglion without
synapse.
 Serves as a communication between
pterygopalatine ganglion and maxillary
nerve.

48. 1.Pharyngeal branch
To mucosa of nasopharynx
2.Palatine branches
Middle and posterior palatine
these innervate soft palate and tonsil
Anterior Or Greater palatine branch
To the mucosa of the palate

49. 3. nasal branches
Posterior superior lateral nasal
Sensory to the mucous membrane of nasal
septum and possterior ethmoidal cells
Medial or septal branch
It innervates the mucous membrane over
the vomer as this continues downward
and forward,reaches the floor of the nasal
cavity,decsnding from there into the
incisal canal to the mucous membrane of
the premaxilla. This nerve is the
nasopalatine nerve

51. Zygomatic nerve
4. orbital branches
These branches are sensory for the
periosteum of the orbit
Emerges in the pterygopalatine fossa. Passes
anteriorly and laterally through inferior
orbital fissure into orbit. Conveys post
ganglionic parasympathetic fibers from
pterygopalatine ganglion to lacrimal
gland.

53. DIVIDES INTO 2 PARTS::
ZYGOMATICOFACIAL NERVE:
 It perforates the facial surface of
zygomatic bone.
 sensory to skin over the prominence of
the zygomatic bone

54. ZYGOMATICOTEMPORAL NERVE:
 It perforate temporal surface of
zygomatic bone through temporal fascia.
 Supplies sensory fibres to skin over the
anterior temporal fossa region.

55. Posterior superior alveolar
nerve
Usually 2-3 in number. Descends from the
main trunk.Pass downward over
posterior surface of maxilla.One branch
remains external to the bone.
 Other branch enter through posterior
alveolar canal on the infratemporal
surface of maxilla and passing from
behind forward in the substance of bone
to the posterior wall of maxillary sinus
and innervating the maxillary molars.

56.  Supplies:
Mucous membrane of sinus, alveolus
,periodontal ligament and pulpal tissue
of the maxillary molars except the mesio
buccal root of maxillary first molar

57. Middle superior alveolar
nerve
 originates in the infra orbital canal.
 Supplies maxillary sinus, premolars,
mesiobuccal root of Molar, buccal soft
tissue in premolar region.
 This nerve forms a ganglion situated at
the junction of posterior superior alveolar
nerve and middle superior alveolar nerve
called the ganglion of valentine
 It is present above the second premolar
teeth.

58. Anterior superior alveolar
nerve
 Origin 6-10 mm before its exit from
incisal foramen.
 It descends in a canal in the anterior wall
of maxillary sinus and divides into
branches which supply the incisor and
canine teeth the canal is called
canalis spinosus
 a gangilon at the junction of anterior
superior alveolar nerve and middle
superior alveolar nerve is called the
ganglion of bockdalek

59.  Supplies: Incisors and cuspid, Anterior
Part of maxillary sinus, Labial gingiva of
incisors and cuspid

61. Inferior palpebral nerve
• 2 or 3 in number.
• Pass upwards & supply sensory fibres to
skin of lower eyelid and its conjunctiva.

62. Lateral nasal nerve
• Pass to skin of the side of the nose.
Superior labial nerve
• 3 or more in number.
• Distributed to the skin & mucous
membrane of the upper lip.

64. Mandibular division
Largest division of trigeminal nerve.
Formed by large sensory root &
small motor root

65. Sensory root Supplies:
 Duramater
 External ear
 Parotid gland
 TMJ articulation
 Lower teeth and gingiva
 Scalp over temporal region
 Ant. 2/3rd of the tongue.
 Skin and mucous membrane of chin,
cheek & lower lip.

66. Motor root supplies
 Muscles of mastication
masseter
Temporalis
Medial and lateral pterygoid
 Mylohyoid & Ant. Belly of digastric
 Tensor tympanii
 Tensor palatini

67. course and distribution
 Motor root is located in middle cranial
fossa
 Sensory root emerges from semilunar
ganglion
 2 roots pass alongside in cranium.
 Emerging from foramen ovale, they unite.

69. MANDIBULAR NERVE
Branches from
undivided nerve
Anterior
Trunk
Posterior
Trunk
Nervous
Spinosus
Nerve to
Medial
Pterygoid
Masseteric
Deep Temporal
Nerve to Lateral
Pterygoid
Buccal
Auriculotemporal
Lingual
Inferior
Alveolar

71. Branches from the
undivided nerve
a.) Nervous spinosus arises outside the skull
and then passes in the middle cranial
fossa through foramen spinosum to supply
duramater and mastoid cells.
b.) Nerve to medial pterygoid
it sinks into the deep surface of the
muscle . A branch supplies tensor veli
palatini and tensor tympani muscles

72. ANTERIOR DIVISION
This is the smaller division
It recieves both motor and sensory supply
Of the muscles of mastication,mucous
membrane of cheek,buccal gingiva and
lower molars.
.A.) Lateral Pterygoid Nerve: Enters the
medial side of lateral pterygoid muscle for
its motor supply.

73. B.) Masseter Nerve:
Passes above the lateral pterygoid to
traverse the mandibular notch and enter the
deep side of masseter muscle. Its gives of
branch to TMJ
C.) temporal branches:
ANT. DEEP TEMPORAL NERVE:: passes
above the upper head of lat. pterygoid,
enters the anterior deep part of the
temporalis muscle.

74. POST. DEEP TEMPORAL NERVE:: Passes
Upwards To Enter The Deep Posterior Part
Of The Temporal Muscle.

75. D.) BUCCAL NERVE:
Passes downwards, anteriorly and
laterally between the two heads of lateral
pterygoid muscle.
AT THE LEVEL OF OCCLUSAL
PLANE,
Sensory innervation to cheek ,Sensory fibres
passes to retromolar triangle,Sensory
fibres to buccal gingivae

77. Posterior division
1. Auriculotemporal nerve:
Course:Passes posteriorly, Deep to external
pterygoid muscle.Between sphenomand.
Ligament & neck of condyle.Traverses upper
deep part of parotid

79. Supplies:
 Temporomandibular joint
 Parotid fascia
 Skin of the temple
 Tympanic membrane

80. 2.LINGUAL NERVE
It lies Medial to lateral Pterygoid In
pterygomandibular space. Lies medial and
anterior to inferior alveolar nerve.enters at
the side of the base of the tongue,medial
to third molar.
Proceeds anteriorly winding around
submandibular duct.
Then reaches the deep surface of sublingual
gland.

82. INFERIOR ALVEOLAR NERVE:
Largest branch of the posterior
division.Passes downwards, (medial side
of lateral pterygoid and ramus) Enters
mandibular foramen,Distributed
throughout mandible Reaches mental
foramen,2 terminal branches
Mental nerve and incisive nerve

83. Supply
inscive nerve:sensory to the teeth incisors
and canine
mental nerve: sensory to skin of lower lip
,chin

84. MYLOHYOID NERVE
Both sensory & motor fibres.
It is given before the inferior alveolar nerve
enters the mandibular foramen
Continues downward & forward in
mylohyoid groove.
Motor fibres Supply:Mylohyoid muscle and
anterior belly of digasric
Sensory fibres supply:chin and
Mandibular incisors.

86. Four major autonomic
ganglion associated with
trigeminal nerve

87. Ganglions
roots
The
cilliary
ganglion
The
pterygopal
atine
ganglion
The
Otic
ganglion
The
submandi
bular
ganglion
Preganglionic /
parasympathetic
Occulomotor
nerve
Greater
petrosal
nerve
Glosopharyn
geal nerve
via the lesser
petrosal
nerve
via chorda
tympani and
lingual
nerve
postganglionic/
parasympathetic
Short cilliary
nerves
Via
zygomatic n
to lacrimal
nerve
Auriculotemp
oral nerve
Secretomot
or fibers to
salivary
glands
Postganglionic
/Sympathetic
Internal
carotid
plexus
Deep
petrosal
nerve/
carotid
plexus
Plexus
around
middle
meningeal
artery
--------------

88. Thank you

89. APPLIED ANATOMY
of TRIGEMINAL
NERVE

90. Contents
 Orofacial pain
 Nerve injuries
 Trigeminal neuralgia
 Nerve involvement in mid face fractures
 Nerve involvement in mandibular fractures
 Nerve involvement in carcinoma
 Superior orbital fissure syndrome
 Frey’s syndrome
 Branches of trigeminal nerve encountered
during various surgical procedures

91.  OROFACIAL REGION PAIN
Pain: - An unpleasant sensory and
emotional experience associated with
actual or potential tissue damage, or
described in terms of such damage.

92. Classification of orofacial
pain:-
 Typical orofacial pain of extracranial
origin:-
 Dental cause: - pulpitis, dentine
hypersensitivity, periapical lesion,
impacted third molar.
 Periodontal: - primary herpetic
gingivostomatitis

93.  Mucosal:-ulcerations, herpetic etc.
 Salivary gland: - sialolithiasis.
 TMJ: - dysfunctions and others.
 Primary neuralgias
 Vascular origin
 Referred pain
 Psychogenic origin

94. pain pathway
MEDIATED FROM THE
SENSORY ROOT INTO
THE PONS
DESCENDIN
G FIBERS
PAIN
PONS BY SPINAL
TRACT FIBERS OF
TRIGEMINAL
NERVE
MEDULLA
SECOND
CERVICAL
SEGMENT
ASCENDING
FIBERS
GENERAL
TACTILE
SENSATION
STIMULUS IN THE REGION
OF TRIGEMINAL NERVE
CONDUCTED AS IMPULSE
ALONG AFFERENT FIBERS
GASSERIAN GANGLION

96. Nerve Injuries
NEUROPRAXIA AXONOTMESIS NEUROTMESIS
SUNDERLAND
CLASSIFICATION
1degree 2,3,4, degree 5 degree
NERVE SHEATH Intact Intact Intrerrupted
AXONS Intact interrupted interrupted
WALLERIAN
DEGENERATION
None Yes, partial Yes, complete
CONDUCTION
FALIURE
Transitory Prolonged Permanent
SPONTANEOUS
RECOVERY
Complete Partial Poor to none
TIME OF
RECOVERY
Within 4 weeks Months Begin by 3
months, if any

98. ETIOLOGY OF NERVE
INJURY
 Wisdom tooth removal
 Facial trauma
 Endosseous Dental implant placement
 Orthognathic surgery
 Salivary gland surgery
 Treatment of benign and malignant lesion
of head and neck
 Endodontic and periradicular surgeries

99. CLINICAL TESTING
 1. Subjective Assessment : Visual Analog
Scale
 2. Objective Assessment :
 Level A : Static 2 point discrimination
 Brush-Stroke directional discrimination
 Level B : Contact detection
 Level C : Pinprick nociception
Thermal discrimination

100. PARESTHESIA:
 Paresthesia is defined as persistent
anaesthesia or altered sensation well
beyond the expected duration of
anaesthesia.
Patient complains of:-
 Numbness
 Sensation of swelling, tingling
 Itching
 Oral dysfunction

101. Causes:
 Injection of LA contaminated with alcohol
 Trauma to nerve sheath during extraction
 Haemmorhage around the nerve
 mandibular implants
Resolves in approximately 8 weeks without
treatment .

102. TRIGEMINAL NEURALGIA
 Also known as: tic douloureux
 DEFINITION: - It is sudden, usually
unilateral, severe, brief, stabbing,
recurring pain in one or more branch of
fifth cranial nerve.

103. Etiology
basilar artery
superior cerebellar artery
compress sensory root
demyelination of nerve fibres
trigeminal neuralgia

104. CLINICAL FEATURES:
 Occurs frequently in patients over 50 yrs.
 Pain is unilateral (rarely bilateral)and
occurs in paraoxysms for 1-2 minutes
 No pain between episodes
 During pain patient grimaces with pain,
clutches his hand over to the affected side
of the face, stops all activity.
 Common trigger zones
include:Lips,Cheek,Ala of nose,Lateral
brow,,Intraoral sites including teeth,
gingivae, or tongue.

106. TREATMENT MODALITIES
Medical:
• Carbamazepine 100mg TDS
• Phenytoin 100mg TDS
• Sodium Valproate 600mg/day
• Clonazepam 1.5mg/day

107. Surgical:
• Peripheral injection of a long acting
anesthetic agent
• Peripheral injection of alcohol
• Peripheral neurectomy
• Cryosurgery
• Selective radiofrequency
thermocoagulation

108. Microvascular nerve root decompression
Posterior fossa approach
separation of superior cerebellar artery
from the sensory root of trigeminal nerve
placement of alloplastic material between
the artery and sensory root

109.  Newer Approaches:
– Acupuncture;
– Physiologic inhibition of pain by TENS
(transcutaneous electric nerve
stimulation)
 Psychological approach
counselling

110. Superior orbital fissure
syndrome
 Ophthalmic nerve and its branches may
rarely undergo transient degenerative
response to ischemia caused by
hematoma and edema pressures exerted
at the superior orbital fissure
 This condition is known as superior orbital
fissure syndrome in which
ophthalmoplegia, Pupillary constriction,
proptosis,peri orbital edema, and ptosis of
eyelid can be seen

112. Frey’s syndrome
 During healing of a penetrating injury in
the region of parotid gland the
secretomotor fibers of the
Auriculotemporal nerve grow out and join
the distal end of the great auriclar nerve
 This leads to formation of beads of sweat
on the skin covering the parotid gland
called gustatory sweating

113. Treatment options
1. Topical agents- antiperspirants and
anticholinergics
2. Radiation therapy-50 gy
3. Surgical procedures-
Auriculotemporal nerve section
Tympanic neurectomy
Skin excision

114. Myofacial pain dysfunction
syndrome (MPDS)
– History of pain: the patient complains
of unilateral or bilateral insidious,
chronic, dull, and aching type of pain.
– Pain is continuous in MPDS
– Palpation: In MPDS the patient
complains of muscle tenderness
– Trigger points when palpated patients
give a positive jump sign

115. Treatment
Medical -Nsaids like aspirin 0.3- 0.6 gm/4 hr
piroxicam 10 -20 mg/3-4 /day
ibuprofen 200-600 mg tds
diazepam 5-10 mg/2-3 /day
amitriptyline 10-25mg tds or
at bed time
Physiotherapeutic modalities
Heat application TENS
Ultrasound occlusal splints
Cryotherapy counterirritants

116. Nerve involvement in
midface fractures
 Zygomatico complex fractures
The injury may produce ecchymosis about
the orbit and anaesthesia in the
distribution of the
infraorbital nerve

117.  Le fort 2 & 3 fractures
Ophthalmic division may be injured resulting
in anesthesia or parasthesia in the region
of innervation

118. Nerve involvement in
mandibular fractures
 Sensory nerve injury, particularly of the
inferior alveolar and mental
nerves,commonly occurs with mandibular
fractures
 Causes of inferior alveolar or mental nerve
injury are displaced fractures, delay in
treatment, and improper use of drill or
screws. Closed reduction is associated
with lower incidence of nerve dysfunction

120. Nerve involvement in
carcinomas
 The clinical history begins with the present
illness and includes the duration and
location of symptoms such as non-healing
ulcer, mass in the oral cavity Or neck,
pain, bleeding, and any symptoms of
cranial nerve deficits.
 A complete examination is performed,
emphasizing sensation over the chin for
mandibular nerve deficit.

121.  Paresthesia of the chin suggests extensive
mandible invasion and inferior alveolar
nerve involvement by oral carcinoma
 The lip is a common site for oral cancer.
Large lesions may invade the mandible or
the mental nerve

122. Branches of trigeminal
nerve encountered during
surgical procedures

123.  When opthalmic nerve is not involved in
trigeminal neuralgia, surgical section of
the inferolateral part of sensory root
interrupts the fibres of maxillary and
mandibular divisions but preserve the
opthalmic division which occupy the
superomedial part of root
 Thereby the corneal sensations are
retained and formation of corneal ulcer is
avoided

124.  Damage to the inferior alveolar nerve may
occur as it runs from mandibular to mental
foramen during visor osteotomy ,cyst
removal, genioplasty, mandibular
resection, causing anaesthesia or
paraesthesia in the area.
 Damage to the infra orbital nerve can
occur at the time of orbital osteotomy and
if retraction during caldwell luc procedure
goes too high.

125.  Preauricular incision sometimes may
damage auriculotemporal nerve
 Temporal extension of the skin incision
should be located posteriorly so that the
main distribution of nerve is dissected and
retracted forward with in the flap
 patients rarely complain about sensory
disturbances that result from damage of
this nerve

126. The lingual nerve, the submaxillary ganglion
and the hypoglossal nerve are situated close
to the gland, disruption of these nerves is to
be avoided during excision of the
submandibular gland .

127.  The lingual nerve usually crosses the duct
at approximately 2nd molar level and is a
helpful point of orientation during floor of
the mouth surgery such as vestibuloplasty
and sialothotomy and tumor excision

128.  While removing lower impacted third
molar, the distal releasing incision should
be given from the distal most point of 3rd
molar across external oblique ridge into
buccal mucosa
 The incision should not be taken on the
lingual aspect of the ridge, as the lingual
nerve can be found at or above the crest
of alveolar ridge, in approximately 17% of
the population

129. the normal position of the lingual nerve is
2mm inferior to the crest and 0.5mm lingual
to the lingual cortex of the mandible in the 3rd
molar region

130. NERVE INJURY DURING IMPLANT
PLACEMENT:
 According to Peterson:
• a minimum distance of 2 mm from the
superior aspect of the bony inferior alveolar
canal
• 5mm from the mental foramen
 There will be a sharp pain and sudden
increase in bleeding if perforated
 Nerve repositioning can be done to avoid
this condition

132. refrences
 Greys anatomy
 Monheims local anaesthesia and pain
control in dental practice
 B.D.chaurasia textbook of anatomy
 Contemparary oral surgery by peterson
 Atlas of human anatomy
 Essentials of human anatomy A K dutta
 Malamad handbook of local anesthesia
 Fractures of mid face and mandible by
killey and kay

133. Thank you