MUSCLE OF MASTICATION SEMINAR

1. Presented by: DR. HIMANSHU SINGH
MUSCLE
OF
MASTICATION

2. Contents
Temporalis
The Masseter
Lateral Pterygoid
Medial Pterygoid
Digastric
Geniohyoid
Classification of Ms of Mastication
Mylohyoid

3. Contents
Classification of Masticatory
Muscle disorder.
What are trigger points?
Clinical aspects of Masticatory
muscle disorder
Conclusion
References

4. “
Nothing is more fundamental to
treating patients than knowing the
Anatomy.”
- Jeffery.P.Okeson.
INTRODUCTION

5. “
• muscle is a soft tissue
• Connects,supports,surrounds other structure/organs
• Including tendons,ligaments,fascia,skin,fibrous
tissue,fat,synovial membrane,muscles
• Produces force and motion
MUSCLE

6. “
Depending upon striations
 Striated and non striated
Depending upon control
 Voluntary and involuntary
Depending upon function
 Skeletal , cardiac and smooth
Classification of muscle

7. “
Smooth muscle is non-striated muscle or
involuntary muscle is found with in walls of organs
and structure such as oesophagus, stomach, intestine
and blood vessels.
Cardiac muscle is also an involuntary muscle and
found only in the heart.
Skeletal muscle is a form of striated muscle which is
under the control of somatic nervous system . As the
name suggests , most skeletal muscle are attached to
bone by bundles of collagen fibers known as tendons.

8. It is a process in which food items are
held,chewed and moved within the oral cavity
in preparation for swallowing.
Chewing = opening + closing + power
stroke
• WILLION L.HYLANDER
• (TEMPOROMANDIBULAR JOINT
DISORDER)
What is Mastication

9. Develop from the mesoderm of the first branchial arch and
are supplied by the mandibular nerve
• but the posterior belly of digastric muscle develops from
second branchial arch and supplied by the facial nerve
Embryologyof muscles of mastication

10. • Depression is brought about mainly by the lateral
pterygoid.
• The digastric, geniohyoid and mylohyoid muscles help
when mouth is open wide or against resistance.
• Elevation is brought about by masseter, the temporalis,
and the medial pterygoid muscles of both side.
• Protrusion is done by lateral and medial pterygoid.
Muscles Producing Movement

11. • Retraction is brought about by posterior fibres of
the temporalis.
• It may be resisted by middle and deep fibres of the
masseter , the diagastric and geniohyoid muscles.
• Lateral and side to side movements are
produced by medial and lateral pterygoids of each
side acting alternately.
Chaurasia B.D. Human Anatomy 4th edition. J.P publication

12. Primary
muscle
Masseter
Temporalis
Lateral pterygoid
Medial pterygoid
Secondary
muscle
Mylohyoid
Geniohyoid
Digastric

13. TEMPORALIS

14. MASSETER

15. • This is a quadrilateral muscles which cover the
lateral surface of the ramus of the mandible.
• Its fiber are arranged in three layers.
The Masseter

16. –ORIGIN
SUPERFICIAL LAYER: form the
• Anterior 2/3 of the lower border of the zygomatic arch.

19. SUPERFICIAL
FIBERS:
•Pass downward and
backword at the
angle of 45 degree.
•Inserted into the
lower part of the
lateral surface of the
ramus of the
mandible

20. MIDDLE AND
DEEP FIBERS:
PASS
Vertically and
downwards.

21. Relations:
SUPERFICIAL :
 Skin,
 Platysma,
 Risorius,
 Zygomaticus major,
 The parotid gland and duct,
 Temporal Branches of the
facial nerve
22

22. • Deep relations:
Temporalis
Ramus Of The Mandible
23

23. NERVE SUPPLY- Massetric nerve(
branch of anterior division of the
mandibular nerve).
ACTION- Muscles elevates the mandible
to close the mouth and clenches the teeth

24. ‘
SUBMASSETERIC SPACE INFECTIONS :-
Sometimes infection around a mandibular third molar tooth
tracks backwards, lateral to the mandibular ramus and pus
localizes deep to the attachment of masseter in the
submasseteric tissue space.
Such an abscess, lying deep to this thick muscle produces
little visible swelling, but is accompanied by profound
muscle spasm and severe limitation of jaw opening
(trismus).

25. TEMPORALIS

26. Temporalis
Fan –shaped ,Fills the temporal fossa

27. The temporal fascia that covers temporalis is a strong
aponeurosis overlapped by auricularis anterior and superior,
the epicranial aponeurosis and the part of orbicularis oculi.
Temporal Fascia

28. • ORIGIN

29. • ORIGIN

30. Nerve supply:
deep temporal branches form anterior
division of mandibular nerve.
Action:
•Elevate mandible
•Posterior fibres
retract and
protrude the
mandible
•Helps in side to
side grinding
movement.

31. Action – Elevation of the mandible

32. Posterior fibers – Draws mandible
backwards

33. Side to side Grinding Movement

34. LATERAL
PTERYGOID

35. LATERAL PTERYGOID
Short,
conical, has
upper and
lower heads

36.  ORIGIN :-
Upper head(small)
•From infratemporal
surface and crest of
greater wing of
sphenoid bone
Lower
head(larger)
From lateral surface of
lateral pterygoid
plate
Grays’s Anatomical basis of clinical practice 39th edition. Elsevier under the Churchill

37. Grays’s Anatomical basis of clinical practice 39th edition. Elsevier under the Churchill

38. Grays’s Anatomical basis of clinical practice 39th edition. Elsevier under the Churchill

39. Fibers
Run backwards and
laterally and converge for
insertion.
Insertion
•Pterygoid fovea on the
anterior surface of neck of
condyle.
•Anterior margin of
articular disc and capsule
of temporomandibular
joint.
•Insertion is posterolateral
and at a slightly higher
level than origin.

40. • SUPERFICIAL:
Relations of the Lateral Pterygoid
•Masseter
•Ramus of
mandible
•Tendon of
temporalis
•Maxillary artery

41. • Deep :
•Mandibular
nerve
•Deep head of
medial pterygoid
•Middle
meningeal artery
•Sphenomandibul
ar ligament

42. Nerve supply
a branch from anterior division of
mandibular nerve.
Action
•Depress mandible to open mouth, with
suprahyoid muscles
•Lateral and medial pterygoid protrude
mandible
•Left lateral pterygoid and right medial
pterygoid turn the chin to left side as part
of grinding movement
•

43. Action – The combined efforts of Digastric and
Lateral pterygoid provide for natural jaw opening.

44. MEDIAL
PTERYGOID

45. THE MEDIAL PTERYGOID
This is
quadrilateral
muscle.
It has small
superficial
head and
large deep
head

46. d4ORIGIN
Superficial head
•From the tuberosity
of the maxilla
•Adjoining bone
Deep head
•Medial surface of the
lateral pterygoid plate
•Adjoining part of
palatine bone

47. d4

48. d4ORIGIN

49. Fibres
•Run downwards,
backward and laterally
Insertion
•Inserted into the
roughened area on the
medial surface of the angle
•Adjoining part of the
ramus of the mandible
•Below and behind the
mandibular foramen
•Mylohyoid groove
Mylohyoid
groove

50. 1111111111111111111111111111111
1111111111111111111111111111111
1111111
Relations of Medial Pterygoid
Superficial relations
Upper part of muscle is
seperated from the lateral
pterygoid muscles by:
•Lateral pterygoid plate
•The lingual nerve
•Inferior alveolar nerve
Lower part of the muscle is
seperated from the:
•Ramus of the mandible
•Maxillary artery
•Sphenomandibular ligament
Maxillary
artery
Ramus
sphenomandibular

53. digastric

54. DIGASTRIC
As the name
implies, has
two bellies –
•Anterior belly
•Posterior belly
Halim A. Anatomy regional and clinical practice 3rd edition. Modern Publishers

55. Anterior belly
Origin
From the diagastric fossa
of the mandible.
Insertion
Two bellies are united by
an intermediate tendon
which is attached to the
•Body
•Greater cornu of the
hyoid bone by fibrous
sling.

56. Anterior belly

57. Relations
It lies on mylohyoid
muscles
Superficial to it are
platysma and cervical
branch of the facial
nerve
Nerve supply
Supplied by mylohyoid
branch of the
mandibular nerve as the
muscle develop in first
brachial arch.

58. ‘Posterior belly
Origin
Mastoid notch
of temporal
bone
Insertion
In to the
intermediate
tendon

59. Nerve supply
Supplied by facial nerve since it is a
second branchial arch muscle.

60. MYLOHYOID

62. Mylohyoid
•This is a flat, triangular
muscle lying deep to
the anterior belly of
digastric.
•The right and left
mylohyoid muscles
together forming the
floor of the mouth.
•Above it lies the mouth
Below it lies the neck

63. Origin:originates from
mylohyoid line of mandible
Insertion: posterior fibers
are inserted into body of
hyoid bone
Middle & ant fibers are
inserted into median raphe
between mandible & hyoid
bone

65. Relation
Superficially
The muscle from the anterior
part of the floor of the
digastric traingle is related to
•Platysma
•Anterior belly of diagastric
•Submandibular salivary
gland
•Mylohyoid nerve and vessels
which occupy the mylohyoid
sulcus on the deep surface of
the mandible
•Submental branch of facial
artery
Anterior
diagastric
Posterior
diagastric
mylohyoid
submental
Platysma

66. Deep relations
•Hyoglossus
•Lingual nerve
•Submandibular gland
•Geniohyoid deep to the
muscle, close to the
midline.
•Styloglossus deep to
the posterior border

67. Nerve supply
Nerve to mylohyoid (branch of mandibular
nerve) since it develops from the first
brachial arch
Action-:
•Raises the floor of the mouth and in doing so
presses the tongue against the palate.
•Elevates the hyoid bone during swallowing
or protrusion of the tongue.

68. GENIOHYOID

69. Geniohyoid
It is a
accessory
muscle of
the tongue
Halim A. Anatomy regional and clinical practice 3rd edition. Modern Publishers

70. Origin
Inferior mental
spine
Insertion
Fibres run
backwards and
downwards to be
inserted into the
anterior surface of
the body of the
hyoid bone.

71. Nerve supply
Through the hypoglossal nerve.
Action
•Elevates the hyoid bone
•May depress the mandible when the hyoid bone
is fixed

72. • As a guide to extra oral digital palpation of the muscles, two
pounds of pressure is the normal recommendation.
• For intraoral palpation one pound or less is normally
recommended.
• The muscles are examined with bilateral palpation for
comparison, for pain, rigidity and size.
• Muscles of mastication are evaluated extra orally and intra
orally by palpation.
Clinical evaluation of masticatory
muscle

73. • palpation of masseter muscle
• Palpation of the deep masseter at their superior
attachment to the zygomatic arches.
• Palpation of the superficial masseter near the lower
border of the mandible.
Palpation of masseter muscle

74. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Palpation of deep Masseter at their superior attachment to the
zygomatic arches. And superficial Masseter near the lower
border of the mandible

75. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
The temporalis muscle is palpated at three sites
as it is a fan-shaped muscle.
• The anterior temporalis muscle is palpated above
the zygomatic arch and anterior to the TMJ.
• The mid region is palpated directly above the TMJ
and superior to the zygomatic arch .
• The posterior temporalis is palpated directly above
and behind the ear .
Palpation of temporalis
muscle

76. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

77. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• Palpation of lateral pterygoid muscle
The little finger is inserted facial to the maxillary teeth and
around distal to the pterygomaxillary, or hamular notch to
palpate the lateral pterygoid muscle
Palpation of lateral pterygoid muscle

78. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
The insertion area of the medial pterygoid muscle at the
inferior inner surface of the body of the mandible can be
approximately palpated with two fingers pressing
upward and laterally against the inner bony mandible.
Palpation of medial
pterygoid muscle

79. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Masticatory Muscle
Disorders

80. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• Myofascial pain
• Myositis
• Myospasm.
• Myofibrotic contraction.
• Centrally mediated myalgia/chronic myositis
• Local myalgia
okeson’s Classification Of Masticatory
Muscles Disorders

81. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• First described by TRAVELL & RINZLER in 1952.
• In 1969 LASKIN described Myofascial Pain Dysfunction
Syndrome.
• Regional, dull aching muscle pain & presence of
localized tender sites(trigger points) in muscle,
tendon or fascia
• Pathogenesis of myofascial pain is not confirmed
Myofascial pain

82. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Regional dull, aching pain, pain aggravated by
mandibular function when the muscles of mastication
are involved.
Hyperirritable sites(trigger points) frequently palpated
within a taut band of muscle tissue or fascia ;
• Greater than 50% reduction of pain with vapocoolant
spray or local anesthetic injection on the trigger point
followed by stretch
Diagnostic criteria for myofascial pain

83. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Reassurance
• Spray & stretch :- flouromethane spray anesthetizes
area allows patient to stretch the muscle in spasm
• Soft diet
• NSAIDS
• Discontinuation of parafunctional habits
• DIAZEPAM 2mg tds -2weeks(anxiety reducing
&muscle relaxing
Treatment

84. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• This disorder is characterized by inflammation of the
muscle due to a spreading infection, external muscle
trauma, or muscle strain.
Clinical features:
• Acute pain within the muscle, which may additionally
be swollen and red, with an overlying increased
temperature.
• The muscle is tender to palpation and may cause a
limited range of motion.
Myositis

85. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
This is the involuntary contraction of a muscle,
causing pain and interfering with its ability to
move.
A myospasm of the inferior lateral Pterygoid
muscles causes constant involuntary contraction and
has a severe effect.
Clinical features:
Inability to occlude.
Limited mouth opening
Myospasm

86. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• Trigger points: “trigger points are clinically
identified as specified hypersensitive areas within
the muscle tissue’’
• A small,firm,tight band of muscle tissue can be felt
• Referred pain: “active trigger points represent a
source of deep pain and can therefore produce
referred pain’’
What are trigger points and referred
pain????

87. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

88. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Trigger points located at sites in the superficial layer of the
Masseter muscle refer to the posterior mandibular and
maxillary teeth , the jaw, and the face .
Toothache is a common complaint from this source.
Myofascial Pain referred from the
Masseter muscle.

89. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

90. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
The reference zone of the temporalis muscle includes all the
maxillary teeth and upper portion of the face .
Headache and toothache are the commonly complaints.
Myofascial pain referred from the
temporal muscle

91. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

92. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
The reference zone for the medial pterygoid muscle includes
the posterior part of the mouth and throat. As well as the
temporomandibular and infra- auricular areas.
Myofascial Pain Referred From Medial
Pterygoid Muscle

93. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

94. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
The lateral pterygoid muscle cannot be adequately palpated,
local or referred pains can be provoked only by isometric
contraction of the corresponding muscle.
The lateral pterygoid muscle pain can radiate to the
temporomandibular joint, and superior lateral pterygoid
muscle refer to zygomatic area.
Myofascial Pain From Lateral
Pterygoid Muscle

95. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

96. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Myofascial pain in the anterior belly of the digastric
muscle often causes referred pain in the lower incisors.
Pain felt behind the angle of the mandible and below the ear
common referral site for a trigger point in the posterior
diagastric muscle.
Myofascial Pain Referred From
Digastric Muscle

97. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’

98. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Synonyms:
Temporomandibular Joint Pain Dysfunction
Syndrome
Masticatory Myalgia Syndrome
Costen’s syndrome
MPDS-myofascial pain
dysfunction syndrome

99. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Etiology:
Trauma
Muscular overextension
Muscular over contraction
Muscle fatigue.
Definition: It is a pain referred from a localized tender
area or trigger point in a taut band of skeletal muscle

100. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
More common in females-80% - 90%
• Pain of unilateral origin
• Diffused & less localized
• Patient is unable to identify exact site involved
• Masseter and lateral pterygoid
• Deviation to unaffected site
• Pain is constant
• More severe in morning
• Gradually worsens as day progresses
• Aggravated by chewing and excessive eating
• Referred to cervical region
• Inability to open mouth
Clinical Features

101. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Four cardinal signs :
1) Pain in pre-auricular region
2) Tenderness in one or more muscles of mastication
3) Clicking / popping noise in the joint
4) Restricted/ deviated mouth opening
Two typical negative disease characteristics
1) Absence radiographic changes in the joint
2) No biochemical evidence of organic changes in the joint
LASKIN′S CRITERIA FOR
MPDS

102. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
1. Removal of the cause
2. Diet modification
3. Injection on trigger point
4. Pharmacotherapy
5. Psychotherapy
6. Acupuncture
7. Moist heat application
Treatment

103. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Trismus-defined as a prolonged,tetanic spasm
of the jaw muscles by which the normal
opening of mouth is restricted(locked jaw)
• Avg interincisal opening -13.7mm(5 to 23mm)
Trismus

104. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
1)Trauma to muscles or blood vessels in infratemporal
fossa associated with dental injections of local
anesthetics.
2)Haemmorhage.
3) LA contaminated with alcohol or cold sterilizing
solutions produce irritation of muscles.
4) Low grade infection after injection.
Etiology

105. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• PREVENTION
1 Use a sharp sterile and disposable needle
2 Thorough knowledge of anatomy to avoid multiple
injections and insertions.
3 Use aseptic technique
4 Practice atraumatic injection
technique

106. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• MANAGEMENT
• Heat therapy-hot moist towels 20mins per hr. on affected
area.
• Warm saline rinses
• Analgesics-aspirin
• Muscle relaxant-diazepam
• Physiotherapy-opening closing mouth,lateral excursions,
for 5 mins every 4 hrs.
• Chewing gums(sugar free)
• Follow up

107. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
“You cannot successfully treat dysfunction unless you
understand function.”
-J.P.Okeson
CONCLUSION

108. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• Management of T.M.disorders & occlusion-J.P.Okeson
• Netter etal Atlas of human anatomy; 672-5
• Neelima Malik (2005): “Textbook of Oral and
Maxillofacial Surgery”1:636-49
• Rispoli DN Benign masseter muscle hypertrophy. Rev
Bras Otorrinolaringol 2008;74(5): 790-3.
• Inderbir singh (human embryology)
• Craniofacial Embryology-Geoffer H.Sperber;pg 133-35
• ‘‘Neuromuscular junction;text book of physiology’’ 10th
edition;pg-728-30
• B.d.chaurasia’s- human anatomy; pg-144-48
References

109. ‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
• Chaurasia B.D. Human Anatomy 4th edition. J.P
publication
• Grays’s Anatomical basis of clinical practice 39th edition.
Elsevier under the Churchill Livingstone publication.
• Conninghamm’s Romanes manual of practical Anatomy 1st
edition. Oxford publication.
• Halim A. Anatomy regional and clinical practice 3rd
edition. Modern Publishers
References