muscles of mastication, dental applications

1. MUSCLES OF
MASTICATION
1
Presented by:
Sohail
1st year PGT
“Nothing is more fundamental to treating
patients than knowing the anatomy”
GOOD MORNING

2.  Introduction
 Development / Embryology
 Muscles of mastication (in detail about each)
 Movements of mandible at TMJ
 Physiology of masticatory muscles
 Mastication – Role of masticatory muscles
- Reflexes
 Investigations
 Disorders of muscles
2

3. INTRODUCTION
 MUSCULUS – “little mouse”
 Is a soft tissue found in most
animals
 Muscle cells -protein filaments
of actin & myosin -contraction –
changes length & shape of the
cell
3

4. DEVELOPMENT
 INTRODUCTION
 Day 17 – 3 germ layers
 Day 19 – mesodermal plate cleaves – diff of somite plate -
somites
 Day 20-21 – 42-44 pairs of somites
 Myocoele, Sclerotome , Dermatome, Myotome
 SKELETAL MUSCLES
 MUSCLES OF MASTICATION
4

5. 5

6. 6

7. 7
By 10th week - muscle masses become
well organized & 5th cranial nerve
branches are incorporated.
By 7th week - cells migrate into areas
where they will differentiate into
muscles of mastication.
During 5th & 6th weeks - primitive
muscle cells from mesoderm of
mandibular arch begin to
differentiate.
4th week- the oral pit is surrounded by several
masses of tissue. Pharyngeal arches are also
evident below the pit & on the sides of the
neck

8. Skeletal muscle –
structure & physiology
 Cylindrical in shape
 Average length – 3cms
 Diameter – 10-100um
8
Muscle
fibre
Tendon BONE

9.  Cell membrane – plasma
membrane/ sarcolemma
 Sarcoplasm
9
1. Nuclei
2. Myofibril
3. Golgi apparatus
4. Mitochondria
5. Sarcoplasmic reticulum
6. Ribosomes
7. Glycogen droplets

10. MYOFIBRIL
 Fine parallel filaments present in the sarcoplam
 Run through the entire length
MICROSCOPIC STRUCTURE
10

11. MUSCLES Of
MASTICATION
11

12.  Rhythmic movement of the jaw is a
series of cyclical movements
 Masticatory system includes
1. Temporomandibular joint
2. Mandible
3. Teeth &
4. Muscles of mastication.
12

13.  Participate in all jaw movements involved in mastication,
deglutition and other non masticatory movements
 Voluntary muscles
 Originate from the skull, span the TMJ, and insert into the
mandible. On contraction, they act to move the mandible.
13

14. TYPES 14
• MASSETER
• TEMPORALIS
• MEDIAL PTREYGOID
• LATERAL PTERYGOID
PRIMARY
• SUPRA HYOID MUSCLES
• DIGASTRIC
• MYLOHYOID
• GENIOHYIOD
• INFRAHYOID MUSCLES
(Sternohyoid,Omohyoid
,Thyrohyoid muscles)
SECONDARY
Dr.Frank Gaillard et al

15. Origin
Insertion
Relations
Vascular supply
Innervation
Actions
Clinical importance
15

16. MASSETER 16
 The width of the muscle at its origin ranges from 27 to 39mm
in brachycephalic skulls, its anterior border length 51 –
70mm, and its posterior length 40 – 62mm.
 Its physiologic cross section is 2.75 cm square
 About 29.9% of the total masticatory muscle mass.
1. SUPERFICIAL LAYER
2. MIDDLE LAYER
3. DEEP LAYER

17. PAROTID FASCIA
 Strong layer of fascia
 Derived from deep cervical fascia
 Covers the masseter and firmly connected to it
 Attached – lower border of zygomatic arch
 Invests the parotid gland
17

18. 18

19. 19
ORIGIN –
• Maxillary process of
zygomatic bone
• Ant 2/3rds of inferior
border of zygomatic
arch
INSERTION -
• Angle
• Lower post half of
lateral surface of
ramus
ORIGIN AND INSERTION
Superficial
layer

20. 20
ORIGIN AND INSERTION
Middle
layer
ORIGIN -
• Medial aspect of ant
2/3rds of zygomatic
arch
• Lower border of post
3rd of this arch
INSERTION -
Central part of ramus of
mandible

21. 21
ORIGIN AND INSERTION
Deep
layer
ORIGIN - Deep surface of
zygomatic arch
INSERTION – Upper part
of
• Mandibular ramus
• Coronoid process

22. RELATIONS
Superficial : Platysma , Risorius ,Zygomaticus
major, Parotid gland, Parotid
duct, Branches of the facial nerve
Deep Surface: Overlies the insertion of
Temporalis &Ramus of the
mandible.
22

23. VASCULAR SUPPLY AND
INNERVATION
23

24. ACTIONS 24
Elevates the
mandible
• Side to side
movement
• Protraction
• Retraction

25. 25

26. CLINICAL
IMPORTANCE
26

27. Massetric hypertrophy Submassetric space infections
27

28.  Variations :-
 Deep masseter fibers may be fused with fibers
of the temporalis muscle
 A connection with the buccinator muscle was observed
by Haller (1978)
 Rare anomaly-phocomelia, the muscle is absent.
 Some fibres may circle around the mandibular angle and
join the medial pterygoid muscle – forming a powerful
sling
28

29. TEMPORALIS 29
Accounts for 37.5 % of the total masticatory muscle mass with a
crosssectional diameter of 4.1 cm 2
- Mc Donald & Andrews 1953
Zenker 1955 ; Schumacher &
Shinker 1960

30. TEMPORAL FASCIA 30

31. 31
ORIGIN
• Whole part of
temporal
fossa
• Deep surface
of temporal
fascia

32. 32
INSERTION
i) Medial surface,
Apex, Ant & post
borders
Coronoid process
ii) Ant border of
ramus of
mandible upto
the last molar
tooth

33. Relations
 Superficial – Skin, temporal fascia, superficial temporal
vessels, Auriculotemporal nerve, zygomatic arch , masseter,
 Anterior border – separated from zygomatic bone by a
mass of fat
 Posterior border – Above – temporal fossa
Below – major components of
Infra temporal fossa
33

34. VASCULAR SUPPLY 34

35. NERVE SUPPLY 35

36. ACTIONS 36
1. Elevates the
mandible
2. Side to side
grinding
movements
3. Posterior fibres –
retract the
protruded
mandible

37. 37

38. CLINICAL IMPORTANCE
 When lower dentures are fitted, they should not
extend into the retromolar fossa to prevent trauma
of the mucosa due to the contraction of the
temporalis muscle.
38
 A plane exists between the temporal fascia which is
attached to the superior surface of zygomatic arch & the
muscle beneath the arch…
 Elevator is introduced into this plane beneath a fractured
zygomatic arch/bone in order to reduce the fracture 
Gillies approach

39. Variations
 Variations in the thickness and surface areas of temporalis
muscle are relatively common.
 Occasionally the muscle is placed far superiorly and closely
approaches the sagittal suture.
 The most anterior tendon insertion may extend very close to the
third molar
 Henke (1884) applied the term “lesser temporalis” to a bundle
that arises from the articular disc of the TMJ lateral to the lateral
pterygoid muscle and fuses with the posterior border of the
temporalis in the deep layer of the masseter muscle.
39

40. MEDIAL PTERYGOID 40

41. ORIGIN AND INSERTION 41

42. Relations
Upper part of muscle is
separated from the lateral
pterygoid muscle by
a) lateral pterygoid plate
b) lingual nerve
c) inferior alveolar nerve
Inferiorly the muscle is
separated from ramus of
mandible by nerves,the
maxillary artery and
sphenomandibular ligament.
Medial surface – tensor palatine
& superior constrictor
Lateral surface - Ramus
42

43. Vascular and nerve supply 43

44. 44Actions
1.Elevation : (bilateral)
2.Protrusion : (bilateral)
3.Contralateral excursion: (unilateral)

45. CLINICAL IMPORTANCE
 IANB
45
 Intraorally ,to palpate the medial
pterygoid muscle slide the index finger a
little posterior to the insertion site of
inferior alveolar nerve block, to where
the muscle is felt & press laterally.

46. LATERAL PTERYGOID
46

47. ORIGIN AND INSERTION
47

48. Relations
SUPERFICIAL
Ramus of the mandible
Maxillary artery
Tendon of temporalis and masseter
DEEP SURFACE
Upper part of the medial pterygoid
Sphenomandibular ligament
Middle meningeal artery
Mandibular nerve
UPPER BORDER
Temporal and massetric branches
of the mandibular nerve
LOWER BORDER
Lingual and inferior alveolar nerve
48

49. BLOOD SUPPLY 49

50. Nerve supply
50
i) 1 for each head –
anterior trunk of
mandibular nerve
ii) A) Upper head ,lateral
part of lower head
– buccal nerve
B) Medial part of lower
head – branch from
the anterior trunk

51. ACTIONS :
Actions by the inferior Head
 Protrusion (bilateral):
The inferior lateral pterygoids are the 2 prime protractors of the
mandible.
 Depression (bilateral):
Contraction of both the lateral pterygoids not only pull the condyles
forward but also along with the suprahyoid & the infrahyoid muscles
help in the depression of the mandible.
 Contralateral Excursion (unilateral):
The insertion of the lateral pterygoids is lateral to its origin & thus
the lateral pterygoid muscle acting singly moves the mandible to
the opposite side.
51

52. ACTIONS BY THE Superior Head:
 The superior lateral pterygoids are inactive during opening.
 They are active during the mandibular elevation or closing
along with Temporalis , Masseter & the Medial pterygoid
muscles.
 The Superior head are particularly active when the teeth ,upon
closure, encounter resistance such as a bolus of food.
 Closure on resistance & the Superior lateral pterygoid play an
active role in this.
52

53. 53
 Slide the fifth finger along the
lateral side of the maxillary
alveolar ridge to the most
posterior region of the
vestibule
( location for PSA nerve block) .
 Palpate by pressing in a
superior, medial, & posterior
direction.

54. CLINICAL IMPORTANCE
 TMJ joint dysfunction –
PTERYGOID SIGN
54

55. Together Medial and Lateral
Pterygoid muscle
Move the mandible to left side
 Left Lateral Pterygoid
 Right Medial Pterygoid
Move the mandible to right side
 Right Lateral Pterygoid
 Left Medial Pterygoid
55

56. Sphenomandibularis-5th
muscle
 Recently discovered.
 Previously thought to be a part of
temporalis.
Origin-
 From infratemporal surface of greater wing
of sphenoid bone.
Insertion-
 Mandible.
Blood supply-
 Maxillary artery, from vessels of medial
pterygoid.
Nerve supply-
 Not yet determined.
56

57. ACCESSORY MUSCLES
of mastication
57

58. DIGASTRIC
Origin – anterior belly from digastric fossa
of mandible , posterior belly from
mastoid notch of temporal bone.
Insertion – intermediate tendon
Innervation - anterior belly by mylohyoid
nerve , posterior belly by facial nerve.
Action – Depresses the mandible ,
elevates the hyoid bone
58

59. 59
 Forms anatomically and
functionally floor of the
oral cavity.
MYLOHYOID
 The right and left muscles are united in the
midline between the mandible and the hyoid bone
by a tendinous strip-the mylohyoid raphae.

60. 60
ORIGIN
 Mylohyoid line on the inner surface of
the mandible.
 Anterior fibers originate from lower
border of the mandible.
 Its most posterior fibers take their origin
from the alveolus of the third molar.
INSERTION
 The posterior fibers run steeply
downwards medially and forward n gets
attached to body of the hyoid bone.
 Majority of fibers however join those of
the contralateral muscles in the
mylohyoid raphae.

61. 61NERVE & VASCULAR SUPPLY:
 Mylohyoid nerve of the mandibular nerve.
 Submental artery, Facial artery
FUNCTION:
 Posterior fibers run vertically from the mandible to the hyoid; if
mandible is fixed, they lift the hyoid bone, and if the hyoid is in
place they depress the mandible.
 Anterior fibers elevate the floor of the oral cavity there by acts
as elevator of the tongue.

62. 62
 ORIGIN
 It arises above the
anterior end of the
mylohyoid line from the
inner surface of
mandible
 including inferior mental
spines by a short and
strong tendon.
 INSERTION
 attached to the upper half
of the hyoid body.
GENIOHYOID

63. 63
Side to side
movements –
temporalis
(same side),
pterygoids
(opp side),
masseter
TMJ MOVEMENTS

64. Summary of the anatomy 64

65. 65
PHYSIOLOGY OF
MASTICATORY
MUSCLES
“You cannot successfully treat dysfunction
unless you understand function”

66. 66
Mastication Deglutition Speech

67. MASTICATION
 Human masticatory motor system –
remarkable machine
 Chewing, swallowing, speech
 Extreme force
1. High force activities
2. Extremely precise movements (speech)
67

68. CONTROL OF MASTICATION
 Voluntary
 Reflex
 Cyclical
 During closing movement – jaw closing muscles on both
sides are activated at the same time
 Opening – only jaw openers are active
 Chewing stroke – activity of left masseter is less than right
masseter because most of the work is being done by the
muscles on the right hand side
 Highly coordinated activity of masticatory, tongue & cheek
muscles
68

69. Mechanisms that modulate muscle
activity during chewing
69
Muscle spindle receptors
Mechanoreceptors in the PDL
Tendon organ reflexes
Joint reflexes

70. Forces of Mastication
 Males – 53-65kg
 Females – 36-45 kg
 Increases with age upto adolescence
70

71. Role of individual muscles in
chewing
 Major jaw closing muscles – masseter & temporalis
 Direction in which the fibres run – indicates the direction in which
they apply force
 Temporalis – most post fibres- pull posteriorly
- most ant fibres- pull upwards & anteriorly
 Lateral pterygoid – imp role in several phases of chewing cycle
( pulls the mandible forward during jaw opening, controls the rate
at which the condyle should return to its fossa during closing)
 Jaw opening muscles – not normally required to exert much force
during chewing
 In jaw opening – contraction of digastric
71

72. INVESTIGATIONS
 Specialised technique that is used to
measure the activity of individual muscles
72
Experimental analysis of
masticatory system To analyse patterns of
masticatory activity with
abnormal masticatory function
ELECTRO MYOGRAPHY

73. 73

74. ETIOLOGY OF
FUNCTIONAL
DISTURBANCES IN THE
MASTICATORY SYSTEM
74
“The clinician who looks only at occlusion is
missing as the clinician who never looks at
occlusion”

75. Events interrupting normal muscle
function
Local factors–
 Restoration in supraocclusion/improperly occluding crown
 Fracture of a tooth
 Secondary to Trauma involving local tissues (post
injection response following L.A, wide opening of
mouth{long dental procedure, yawning}, unaccustomed
use{bruxism, biting on hard object, gum chewing})
 Deep pain input
Systemic factors-
 Emotional stress
 Acute illness or viral infections
 Constitutional patient factors( immunologic resistance)-
affected by age, gender, diet
75

76. 76
• Speaking
• Chewing
• Swallowing
Functional
• Clenching/grinding of
teeth
• Oral habits
Parafunctional/
Nonfunctional
Activities of masticatory system
Muscle hyperactivity
Parafunctional activities +
general increase in level of
muscle tone

77.  common finding
 rarely associated with symptoms
 Self limiting phenomenon
 Not related to increased risk
77BRUXISM IN CHILDREN
-Explain parents the benign
nature
- Monitor any complaints of child
If masticatory function –
problem, evaluate the child in
dental office
If frequent & significant
headaches – TMD examination
also indicated – to rule out
masticatory dysfunction as a
possible cause

78. SIGNS AND
SYMPTOMS OF
DISODERS OF
MUSCLES
78
“You can never diagnose something
you have never heard about”

79. 79
PAIN
DYSFUNCTION

80. PAIN
 Most common complaint
 Central mechanisms
 Slight tenderness – extreme discomfort
 MYALGIA
 Muscle fatigue, tiredness
 Origin – certain allogenic substances Muscle pain
 Severity of muscle pain ∞ functional activity of muscle
 Cyclic muscle spasm
 Headache
80

81. DYSFUNCTION
 Common clinical symptom
 Decrease in range of mandibular movement clinically seen
as inability to open mouth widely
 Acute malocclusion
81

82. 82Protective co-
contraction
Local muscle soreness
Myofascial pain
Myospasm
Chronic centrally
mediated myalgia
Fibromyalgia
Masticatory
muscle
disorders

83. 83Clinical masticatory muscle pain model

84. Protective co-contraction
(Muscle splinting)
 First response of muscles to any event
 CNS response to injury or threat of injury.
 Co - contraction of antagonist muscles (during opening of mouth
increased activity of elevator muscles and vice versa)
 Normal protective or guarding mechanism.
 Not a pathologic condition – prolonged – may lead to muscle
symptoms
84

85.  Etiology- Any change in sensory input from associated
structures {High restoration/crown ,deep pain input or
emotional stress}
 Clinically - Muscle weakness following an event
 No pain occurs when muscle at rest - Use of muscle increases
pain.
 Limited mouth opening but when slowly opened-full
opening.
 Key factor- immediately follows an event(history)
 If continues (hrs-days) -muscle can become compromised 
local muscle problem
85

86.  Treatment –
DEFINITIVE TREATMENT
 Directed towards the reason for co-
contraction
 Trauma – no definitive treatment
 Altering the restoration, occlusal condition
SUPPORTIVE TREATMENT
 When cause is tissue injury
 Restrict use of mandible
 Soft diet
 NSAIDS
86

87. Local muscle soreness
(Non inflammatory myalgia)
 1st response to prolonged co-contraction.
 Co-contraction- CNS induced muscle response
 Soreness- changes in local environment of muscle tissue
 ( release of bradykinin, substance P)
 Excessive use- ‘delayed onset muscle soreness’ or ‘post exercise
muscle soreness’
 Co-contraction-cyclic event.
 Clinically – muscle –tender on palpation, increased pain on
function, structural dysfunction, limited mouth opening, acute
muscle weakness
87

88.  DEFINITIVE TREATMENT
 Eliminate ongoing altered sensory input
 Eliminate source of deep pain
 Restrict mandibular use
 Reduce non functional tooth movements
 Decrease emotional stress
 SUPPORTIVE TREATMENT
 Mild analgesic –every 4-6hrs for 5-7 days
 Passive muscle stretching, gentle massage
88

89. Central nervous system effect on
muscle pain
1) Secondary to Ongoing deep pain input.
2)Arise from central influences such as upregulation
of the autonomic nervous system {Emotional
stress}
3)Changes in descending inhibitory system.
89
Clinician should appreciate that muscle pain
now has a central origin

90. 90
Centrally influenced muscle
pain disorders
Acute Myalgic
disorders
Myospas
m
Chronic myalgic
disorders
Regional
myalgic
disorders
Myofascial
pain
Chronic
centrally
mediated
myalgia
Systemic
myalgic
disorders
Fibromyalg
ia

91. Myospasm (Tonic Contraction Myalgia)
 Myospam of masticatory muscles –not common.
 Etiology- local muscle conditions (muscle fatigue, changes in
electrolyte balances) ,deep pain input
 Clinically - Structural dysfunction( jaw positional changes
acute malocclusions ), firm muscles on palpation
 Short lived (similar to leg cramps)
 Repeated –DYSTONIA
 Mouth forced open (opening dystonia), or closed(closing
dystonia) or even off to 1 side
91

92.  DEFINITIVE TREATMENT
Reducing the spasm
 Reducing the pain
 Passively stretching the involved muscle
 Manual massage
 Injection – 2% lignocaine without vasoconstrictor
Elimination of the factor
 Secondary to fatigue –rest
 SUPPORTIVE TREATMENT
 Physical therapy
 Deep massage& passive stretching
 Muscle conditioning exercises
 Relaxation techniques
92

93. Myofacial pain (Trigger point Myalgia)
 1st described – Travel & Rinzler -1952
 Arises from hypersensitive bands of muscle tissue – TRIGGER
POINTS
 Felt as taut bands when palpated elicit pain
 Source of constant deep pain central excitatory effects 
referred pain reported as headache pain
 Etiology- trauma,hypovitaminosis, fatigue,viral infections,
emotional stress
 Clinically – trigger points, no local muscle sensitivity, mostly
related to central effects (referred pain)
93
For treatment to be effective, it must be directed
towards the source of pain

94.  Diagnosis – trigger points (active/latent)
 Activated by various factors (increased use of muscle,
strain on muscle, emotional stress, upper resp. tract
infections )  headache returns
 Other central excitatory effects – secondary hyperalgesia,
co-contraction, local muscle soreness
94
Clinical symptoms are associated with the central excitatory
effects created by trigger points and not the trigger points
themselves

95.  DEFINITIVE TREATMENT
 Eliminate source of deep pain
 Reduce local & systemic factors
 Proper sleep (TCA)
 Elimination of trigger points (spray & stretch,
pressure & massage, injection & stretch)
 SUPPORTIVE TREATMENT
 Physical therapy
 Manual techniques(soft tissue immobilization,
muscle exercises)
 Muscle relaxants, analgesics
95

96. Characteristic sign of MPDS------
LASKIN'S 4 CARDINAL SIGNS
 Unilateral pain
Muscle tenderness
Clicking and popping noise in TMJ
Limitation of jaw function or deviation of jaw
 Laskin also emphasized that other than the above positive
signs,,the following signs must be absent
 There should be absence of clinical,radiographic or
biochemical evidence of organic changes in TMJ
There should be no tenderness on palpation via external
auditory meatus
96

97. Perpetuating factors for Chronic Myalgias
LOCAL
1. Protracted cause
2. Recurrent cause
3. Therapeutic mismanagement
SYSTEMIC
1. Continued emotional stress
2. Downregulation of descending inhibitory system
3. Sleep disturbances
4. Learned behavior
5. Secondary gain
6. Depression
97

98. 5) Centrally mediated myalgia (Chronic
myositis)
 Originating from CNS effects felt peripherally in the muscle
tissues
 Symptoms similar to inflammatory condition - MYOSITIS
 Neurogenic inflammation
 Etiology – Prolonged input of muscle pain + local soreness,
central mechanisms
 Clinically - Continuity of muscle pain ,Constant aching
myogenous pain , Pain present during rest and increases with
function, muscles are tender to palpate, structural dysfunction.
98

99.  DEFINITIVE TREATMENT
 Recognize condition correctly
 Restrict mandibular movement
 Avoid exercise /injections
 Disengage the teeth
 NSAIDS
 SUPPORTIVE TREATMENT
 Careful physiotherapy
 Moist heat/cold packs
 Gentle stretching
99

100. Chronic systemic myalgic disorders
(Fibromyalgia)
 Global musculoskeletal pain disorder
 Often confused with acute masticatory muscle disorder
 Tenderness - 11 or more of 18 specific tender point sites
throughout the body.
 Etiology – central mechanism
100

101.  DEFINITIVE TREATMENT
 When other masticatory muscle disorders-
present –therapy
 Perpetuating factors – properly addressed
 NSAIDS
 Sleep
 Depression – managed
 SUPPORTIVE TREATMENT
 Physical therapy
 Manual techniques(moist heat, gentle massage,
passive stretching, relaxation)
 Mild, well controlled exercise
101

102. MUSCULAR DYSTROPHIES
 Rare , inherited muscle diseases
 Muscle fibres are abnormal due to a genetic defect
 Progressively weaker
 Replaced by fat and CT
 Deficiency / malfunction of the muscle protein
(dystrophin / dystropin associated proteins)
102

103. Duchenne’s muscular
dystrophy
 Most common form of muscular dystrophy
in children
 Young boys
 Muscles of pelvis & limbs – 1st affected
 Masticatory system – involved later
103
Weakness in masticatory & facial muscles
Abnormal patterns of force production
Remodelling of facial bones , malocclusions

104. Myotonic dystrophy
 Muscular dystrophy – affects adults
 5 in 100,00
104
Abnormalities in ion channels of
muscle membranes
Leads to
Muscle weakness along the with
muscle stiffness
Inability to relax muscle rapidly
after effort

105. MYOSITIS OSSIFICANS
TRAUMATICA
 Masseter muscle – occasionally affected
 Uncommon sequel to TRAUMA (surgery) /
INFLAMMATION OF MUSCLES
 Calcified lesions – X rays/ other scans
105

106. GUILLAIN – BARRE’
SYNDROME
 Generalised neuropathy
 Inflammation of peripheral nerves
 Severe weakness & numbness
 2 in 100,000….increases with age
 Triggered by – stress, viral infection , surgery
 Most people – recover fully
 20% - residual sensory / motor defects
106

107. BRUXISM
 Parafunctional activity
 Clenching/grinding of teeth
 1 of the structures involved- Muscles of mastication
 Fatigue to muscles of mastication
 Not giving them time to relax
 Tender
107

108. Trismus/Lock jaw
 Inability to open mouth/reduced opening of jaws
 Causes- inflammation of muscles of mastication, needle prick to
medial pterygoid
 Management- Analgesics, muscle relaxants ,
antibiotics,physiotherapy
108

109. Mandibular fractures & muscles of
mastication
 Main role in unfavourable fractures
 3 muscles exhibit a strong upward pull on the posterior
mandible and act to close the mouth
 Displace posterior segment superiorly
 Fracture of Condyle – Anteromedial – Lateral Pterygoid
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110. Space infections
Masticatory spaces:
 Pterygomandibular
 Submasseteric
 Superficial temporal
 Deep temporal
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 Formed by splitting of investing fascia into superficial &
deep layers
 Superficial layer – lies along lateral surfaces of masseter &
lower half of temporalis muscle
 Deep layer – passes along medial surface of pterygoid
muscles

111. Submassetric space
 3 layers of masseter fused anteriorly, separated posteriorly
 Space b/n middle & deep heads
 Insertion – loose intermediate tendon
 Easy accumulation of pus
 Submassetric space abscess – pus b/n masseter& ramus
 Lower 3rd molars
 Swelling -
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112. Pterygomandibular space
 Involvement – infected 3rd molars, infection due
to contaminated needle used for IANB, infection
from maxi 3rd molar after PSA
 Established infections- no much swelling on face
 Severe degrees of limitation of mouth opening
 Tenderness – soft tissues medial to ant.border of
ramus
 Dysphagia
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113. Temporal space
 Secondary to initial involvement of
pterygopalatine & infratemporal space (roots of
upper molars)
 Related to temporalis muscle
 Superficial – b/n fascia & muscle
 Deep – deep to muscle
 Pain, trismus, swelling over temporal region
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114. Points to remember….
 Submassetric space abscess – pus b/n masseter& ramus
infection from Lower 3rd molars.
 Pterygomandibular space - Infected 3rd molars,
infection due to contaminated needle used for IANB
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115. REFERENCES
 Gray’s Anatomy – the anatomical basis of clinical practice, 40th edition,
Churchill and Livingstone
 James L Hiatt, Lesie P.Gartner - Textbook of head and neck anatomy - 3rd
edition - Wolters company,
 B.D. Chaurasia’s, Human anatomy, vol 3 - 4th edition - CBS publishers –
2004
 T.W. Saddler - Langman’s medical embryology - 9th edition - Wolters
Kluver publishers
 Management of temporomandibular disorders and occlusion- Jeffrey P.
Okeson - 6th edition
 Clinical oral physiology- Timothy S. Miles, Peter Svensson
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