tmj mastcation

1. MUSCLES OF
MASTICATION
Dr. Navendra Jha
Department of Oral Medicine & Radiology

2. CONTENTS
 INTRODUCTION
 CLASSIFICATION
 DEVELOPMENT OF MUSCLES OF MASTICATICATION
 ANATOMY
ORIGIN
INSERTION
NERVE SUPPLY
 CLINICAL EXAMINATION OF MUSCLES OF MASTICATION
 APPLIED ASPECT OF MUSCLES OF MASTICATION
 REFERENCES

3. INTRODUCTION
 These are the muscles that move the mandible during mastication, speech
and deglutition.
 They are:
1) Masseter muscle
2) Temporalis muscle
3) Lateral pterygoid
4) Medial pterygoid
 These 4 pair of muscle are the primary muscle of mastication.

4. ACCESSORY MUSCLES
A. Suprahyoid muscles
a) Mylohyoid muscle
b) Geniohyoid muscle
c) Stylohyoid muscle
d) Digastric muscle
B. Infrahyoid muscles
a) Sternothyroid muscle
b) Omohyoid muscle
c) Thyrohyoid muscle
d) Sterohyoid muscle

5. DEVELOPMENT

8. ANATOMY

9. MASSETER
S
 Greek word “masseter”- a
chewer
 This is a quadrilateral
muscle which covers the
lateral part of ramus of
mandible.

10. ORIGIN
INSERTION
NERVE SUPPLY
ACTION

14. TEMPORALIS

15. ORIGIN
INSERTION
NERVE SUPPLY
ACTION

16. Showing action of masseter and temporalis

19. LATERAL PTERYGOID
It is a short thick conical muscle with definite upper and lower heads

21. ORIGIN
INSERTION
NERVE SUPPLY
ACTION

25. MEDIAL PTERYGOID
This is quadrilateral muscle
having a small superficial
head and a large deep head
which forms the major part
of muscle

27. ORIGIN
INSERTION
NERVE SUPPLY
ACTION

31. ACCESSORY MUSCLES

34. SUPRAHYOID MUSCLES
1. DIGASTRIC MUSCLE
it has two bellies joined by a central tendon
ORIGIN
ANT. BELLY- from digastric fossa
POST. BELLY- mastoid notch on temporal bones
INSERTION
both the belly connected each other by a fascial sling to
the junction of body and greater cornu of hyoid bone
ACTION
depression of chin during opening of mouth
NERVE SUPPLY
1. inferior alveolar nerve 2. facial nerve

35. 2. STYLOHYOID
ORIGIN
middle of the post. Surface of styloid process
INSERTION
junction of the body and greater cornu of hyoid
bone anteriorly
ACTION
it draws the hyoid bone upward and backwards
NERVE SUPPLY
facial nerves

36. 3. MYLOHYOID
ORIGIN
mylohyoid line
INSERTION
body of hyoid bone
ACTION
elevation of floor of mouth during swallowing
depression of mandible
NERVE SUPPLY
branch of inferior alveolar nerve

37. 4. GENIOHYOID
ORIGIN
inferior genial tubercle on symphysis menti
INSERTION
body of hyoid bone
ACTION
Draws the hyoid bone upward and forward
NERVE SUPPLY
C1 fibers via hypoglossal nerve

38. INFRA HYOID MUSCLE
1. STERNOHYOID
ORIGIN
upper part of posterior surface of manubrium sterni
capsule of sterno clavicular joint
INSERTION
fibers of both sides converges up to the lower border
of body of hyoid bone
ACTION
depression of hyoid bone
NERVE SUPPLY
ansa cervicalis (c2 and c3 fibers )

39. 2.OMOHYOID
ORIGIN
superior belly – intermediate tendon beneath the sterno
mastoid
inferior belly - upper border of scapula near the supra
scapular notch
INSERTION
superior belly – lower border of body of hyoid bone
inferior belly – intermediate tendon
ACTION
depression of hyoid bone
NERVE SUPPLY
superior belly – c1 fibers
inferior belly – ansa cervicalis

40. 3. STERNOTHYROID
ORIGIN
post. Surface of manubrium deep to sterno
hyoid
INSERTION
olique line of thyroid cartilage below
thyrohyoid
ACTION
depression of larynx
NERVE SUPPLY
ansa cervicalis (c2 ,c3)

41. 4. THYROHYOID
ORIGIN
upper part of oblique line on thyroid cartilage
INSERTION
lower border of greater cornu of hyoid bone
ACTION
depression of hyoid bone
NERVE SUPPLY
fibers of c1 via hypoglossal nerve

42. PALPATION OF MUSCLES

46. Lateral pterygoid
 D
Done by placing the forefinger or the little finger, over the buccal area of the
max. 3rd molar region and extending pressure in a post. Superior & medial
direction behind the max. tuberosity

47. Medial pterygoid

48. This chart is showing role of the all muscle and their
action
1.Depression of mandible
(opening of mouth)
2.Elevation of jaw
(closing of mouth)
Lateral pterygoid
Geniohyoid
Mylohyoid
Digastric
Masseter
Temporalis
Medial pterygoid

49. 3. Protusion
4.retraction
Lareral movement
Lateral pterygoid
and
Medial pterygoid
Post. Fibers of temporalis
Masseter,Geniohyoid
digastric
Medial and lateral pterygoid

53. CLINICAL SIGNIFICANCE
AND
APPLIED ASPECT

54. MASTICATORY MUSCLE DISORDER
Okeson’s Classification Of Masticatory Muscles
Disorders
 Myofacial pain dysfunction syndrome
 Myositis
 Myospasm.
 Myofibrotic contraction.
 Centrally mediated myalgia/chronic myositis
 Local myalgia

56. ETIOLOGY
 Trauma
 Muscle overextension
 Muscle overcontraction
 Muscle fatigue
 Parafunctional habits
 Physiologial stress
 Sleep disturbance
 Nutritional problem
 Injuries to the tissue

57. CLINICAL FEATURES
 Females are more affected-80% to 90%
 unilateral diffused pain
 Constant pain
 Chewing aggravates pain
 Inability to open mouth

58. TREATMENT
 Removal of the cause
 Diet modification
 Pharmacotherapy
 Moist heat application
 Psycotherapy
 Acupunture
 Injection on trigger point

59. TRISMUS
Defined as a prolonged, tetanic spasm of the jaw muscles
by which the normal opening of mouth is restricted.
ETIOLOGY
trauma
haemmorhage
contaminated LA
low grade infection
TMJ disorder

60. INTRA ARTICULAR CAUSE
osteoarthritis
TMJ dislocation
internal dearrangement of TMJ
septic arthritis
ankylosis
intracapsular fracture

61. EXTRA ARTICULAR CAUSE
trauma
prolonged dental treatment
post surgical edema
tetanus
pericoronitis
odontogenic infection

62. Treatment
treatment of trismus varies depending on the
etiological factor .

63. CONCLUSION
Muscles of mastication help in chewing, elevating
protruding, retruding and lateral shifting of mandibular
movements.
It also helps in speech, thus it is important for a normal
physical health which leads to a secure psychological
influence

64. REFERENCES
 Management of T.M.disorders & occlusion-J.P
.Okeson
 B.d.chaurasia’s- human anatomy; pg-144-48
 Neelima Malik (2005): “Textbook of Oral and Maxillofacial
Surgery”1:636-49
 Grey’s antomy textbook
 Inderbir singh (human embryology
 ‘‘Neuromuscular junction;text book of physiology’’ 10th edition;pg-728-
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