Muscles of mastication

1. Presented by :- Dr. Sushma Tomar
Associate Professor
Department of Anatomy

2. MUSCLES OF MASTICATION
PRINCIPAL MUSCLES OF
MASTICATION-
o Four paired muscles:-
o Masseter
o Temporalis
o Medial Pterygoid (internal
pterygoid)
o Lateral Pterygoid (external
pterygoid)
ACCESSORY MUSCLES OF
MASTICATION-
1) Buccinator
2) Digastric

3. MASSETER
oQuadrilateral muscle.
oConsists of 3 layers of fibers.
ORIGIN:
Superficial layer (largest):-
•Lower border of anterior 2/3rd of zygomatic arch.
•Adjoining maxillary process of zygomatic bone.
Middle layer:-
•Lower border of posterior 1/3rd of zygomatic arch.
Deep layer:-
•Deep surface of zygomatic arch.

4. MASSETER contd…
INSERTION: Lateral surface of the ramus of the
mandible.
NERVE SUPPLY: Masseteric branch of anterior
division of mandibular nerve.

5. MASSETER contd…
ACTIONS:
o Elevation of the mandible.
o Protraction of mandible (by superficial fibers).
o Retraction of mandible (by deep fibers).

6. APPLIED ASPECTS OF MASSETERS
TRISMUS
• Tonic spasm of both masseters in tetanus.

7. TEMPORALIS
• A fan-shaped muscle.
• Bipennate muscle.
ORIGIN:
o Floor of temporal fossa
below the inferior temporal
line.
o From overlying temporal
fascia.
 It covers the majority of the
temporal bone and lesser
portions of the frontal and
parietal bones.
INSERTION:

9. TEMPORALIS contd…
NERVE SUPPLY:
o Deep temporal branches of mandibular
nerve.
ACTIONS:
o Elevation of mandible.
o Retraction [Retrusion (pull back) ] of the
mandible (by posterior fibers).

10. MEDIALPTERYGOID
(INTERNAL PTERYGOID)
o Quadrilateral muscle.
ORIGIN:
o Arises by 2 heads -
Superficial head.
- Deep
head.
SUPERFICIAL HEAD (small):-
o From tuberosity of maxilla.
o Lateral surface of pyramidal
process of palatine bone.
DEEP HEAD (large):-
o Medial surface of lateral
pterygoid plate.
INSERTION: Medial surface of

12. MEDIALPTERYGOID contd…
NERVE SUPPLY:
o Branch from trunk of mandibular nerve.
ACTION:
o Elevation of mandible (closing of mouth).
o Protrusion of mandible (along with lateral
pterygoid).
o Side to side movements of mandible
(chewing) (lateral and medial pterygoid
muscles of two sides contract alternately).

13. LATERAL PTERYGOID
(EXTERNAL PTERYGOID)
o Key muscle of
infratemporal region.
ORIGIN:
o Arises by 2 heads- Upper
head.
- Lower
head.
UPPER HEAD:-
• Infratemporal surface and
infratemporal crest of
greater wing of the
sphenoid.

15. LATERAL PTERYGOID contd…
INSERTION:
o Pterygoid fovea at anterior surface of Neck of mandible.
o Capsule and articular disc of temporo-mandibular joint.
NERVE SUPPLY:
o Branch from anterior division of mandibular nerve.

16. LATERAL PTERYGOID contd…
ACTIONS:
o Depression of mandible (opening of mouth).
o Protrusion of mandible (along with medial pterygoid)
o Side to side movements of mandible (chewing) (lateral and
medial pterygoid muscles of two sides contract alternately).