4. MUSCLE
Webster’s - Bundles of cells or fibers that
can be contracted for bodily movement
Oxford - Bundles of contractile fibers
producing motion in animal body
Saunder's Encyclopedia - Bundles of fibers
that have the power to contract and hence to
produce movement
6. MASTICATION
Mastication is defined as
“Process of chewing food in preparation for
swallowing and digestion”.
Dorland’s medical dictionary
“The process of chewing food in preparation for
deglutition & digestion; the act of grinding or
comminuting with the teeth”.
Stedman’s medical dictionary
7. DEVELOPMENT
5th-6th week
•Primitive cells form and differentiate
•Get oriented to site of origin and insertion
7th week
•Mandibular arch mass enlarges
•Cell migrates to areas of formation of four major muscles of
mastication
•Cell differentiation
10th week
•Muscle mass well organised
•Nerve masses get incorporated
11. SUPERFICIAL LAYER
Origin:
• zygomatic process of the
maxilla.
anterior 2/3 of the lower
border of the zygomatic
arch.
• Run downwards and
backwards.
Insertion:
• Angle and lower half of
the lateral surface of the
ramus .
12. MIDDLE LAYER
Origin
• Deep surface of the anterior
2/3rd of the zygomatic arch
and lower border of the
posterior 1/3rd of the
zyomatic arch
• passes vertically down
wards.
Insertion
• Ramus of the mandible.
13. DEEP LAYER
Origin
Posterior third of the
lower border and medial surface
of the
zygomatic arch
• Fibers run vertically downward.
Insertion
Upper half of the ramus
lateral surface-coronoid process
29. ORIGIN –
SUPERFICIAL HEAD- Tuberosity of
maxilla & palatine bone
DEEP HEAD - Medial surface of
lateral pterygoid plate
INSERTION –
Medial surface of ramus inferior to mandibular
foramen
34. BUCCINATOR
• Also known as whistling
muscle.
• ORIGIN
• Upper fibres-Maxilla
opposing molar teeth
• Lower fibres-Mandible
opposing molar teeth
• Middle fibres-
Pterygomandibular raphe
35. INSERTION
•Upper fibers -Straight to upper lip.
•Lower fibers -straight to lower lip.
•Upper of middle fibers cross the
angle of mouth to run into lower lip
and lower run into upper lip.
36. • BLOOD SUPPLY
• Facial Artery
• NERVE SUPPLY
• Facial Nerve
• ACTIONS
• Flattens cheek during mastication
• Prevents accumulation of food in vestibule
38. MYLOHYOID
ORIGIN – Mylohyoid line of
mandible.
INSERTION – Hyoid bone,
median raphe.
NERVE SUPPLY -
Mylohyoid nerve.
ACTION – Elevates the floor
of the mouth, depresses the
mandible.
39.
40. GENIOHYOID
ORIGIN – Genial Tubercle
INSERTION– Anterior
surface of the body of hyoid
bone.
NERVE SUPPLY – First
cervical nerve.
ACTION – Elevates the hyoid
bone, depress the mandible
when hyoid is fixed.
41. ORBICULARIS ORIS
• 2 PARTS
• Intrinsic-originate from superior and
inferior incisivus
• inserts into the angle of mouth.
• Extrinsic-formed by elevator and
depressor muscles of the lips and inserts
into the angle of the mouth.
• Function- close and shut the mouth
• Forms the most versatile types of
grimaces.
42. MASTICATORY CYCLE
• The pathway of mandible
in chewing is referred to as
chewing or masticatory
cycle”
44. 1. Opening phase-the condyles move in downward and forward
direction.
2. Closing phase-mandible moves laterally to the chewing side.
•Chewing side condyle- forward and lateral movement
•Non chewing side condyle-upward and backward.
3.Intercuspal phase- Tooth to tooth contact occurs
45. • Average jaw opening 16-20mm.
• Duration of masticatory cycle - 0.6-1 second.
• Men chew faster and have shorter occlusal phase than
women.
• Chewing patterns is also influenced by consistency , shape
,size and taste of the food.
47. APPLIED ASPECTS
• BRUXISM
• Bruxism is the habitual
grinding of teeth when the
individual is not chewing or
swallowing”. (Ramfjord
1966)
• TYPES
1. Day time
2. Night time
48. CLINICAL SIGNS
• Tenderness- jaw muscles
lateral pterygoid and masseter muscle.
• Hypertrophy of the masseter muscle unilaterally or
bilaterally.
• Muscular fatigue on waking.
53. MYASTHENIA GRAVIS
• Auto immune disease
• Auto-antibodies to acetyl
choline receptors
• Profound weakness of
muscles
• Characterized by:
• Diplopia
• Ptosis
• Drooping of face
54. DENTAL INTERESTS
• Muscles of mastication and muscles of facial expression.
• Difficulty in mastication and deglutition
• Slow slurred speech.
• Treatment
• Anti - cholinesterases (IM)
• (Neostigmine)
55. MYOFACIAL PAIN
DYSFUNCTION SYNDROME
• TMJ pain dysfunction
syndrome, Masticatory
myalgesia syndrome.
• Definition: MPDS is a
pain disorder in which
unilateral pain is referred
from the trigger points in
myofacial structures to the
muscles of head and
neck.(Laskin)
56. CAUSES
• Overextension
• faulty dental restoration or prosthesis (High point)
• Over contraction
• bilateral loss of posterior teeth,
• continued loss of alveolar bone
• Muscle Fatigue
• Chronic Oral habits such as grinding or clenching of teeth
• Mechanical reasons or emotional reasons
57. Clinical features:
• Age : 15-40 yrs
• Female : male ratio= 3:1
• Pain
• Muscle tenderness
• TMJ Clicking
• Limitation of jaw movements
Negative signs
a. Absence of Clinical, Radiographic or Biochemical changes.
b. Lack of tenderness in the TMJ area
58. Signs: –Laskins four cardinal signs
• Dull aching pain in ear or preauricular region
• Muscle tenderness -over neck of mandible, distal and
superior to maxillary tuberosity
• TMJ Clicking
• Limitation of jaw movement/ deviation of mandible on
opening.
59. Treatment of MPDS
• DEFINITIVE THERAPY
• SUPPORTIVE THERAPY
• OTHER TREATMENT
MODALITIES
60. DEFINITIVE THERAPY
• Treatment and elimination of the trigger points.
• This is accomplished by painlessly stretching the muscle
containing the trigger points.
61. Spray and stretch
Vapocoolent sprays- cooling
of skin over the involved
muscles.
eg. Fluromethane (refrigerant
spray)
Pressure and massage - 20 lb for 30-60 sec
63. SUPPORTIVE THERAPY
• Various physical therapy modalities and manual techniques
are used to treat myofascial pain.
• Physical Therapy
• They can be divided into the following types:
• Thermotherapy.
• Coolant therapy.
• Ultrasound.
• Transcutaneous electrical nerve stimulation (TENS).
• Acupuncture,
64. OTHER TREATMENT
MODALITIES
Soft diet & restricted wide mouth opening
Aspirin or NSAID
Anxiolytic agents - Benzodiazepams etc.
Muscle relaxants- Mephenesin
Antidepressants
65. CONCLUSION
• The masticatory muscles include a vital part of the orofacial
structure and are important both functionally and structurally.
• The proper management and periodical examination of the
muscles may provide a greater chance of catching the disease
process at an early stage which may be useful for its better
prognosis.
66. REFERENCES
• Gray's Anatomy, 13th Edition, Williams and Worwick, ELBS
Publication, 534-543.
• Cunningham's Text Book of Anatomy, 12th Edition,
G.J.Romones, ELBS Oxford Publication, 265-288.
• Human Anatomy, Regional and Applied, Head and Neck and
Brain, Chaurasia, 74-78
• Textbook of oral pathology- Shafer’s
• Electronic media
