This document discusses the muscles of mastication, including the four principal muscles - masseter, temporalis, medial pterygoid, and lateral pterygoid. It describes the origin, insertion, nerve supply, and actions of each muscle. Additionally, it mentions two accessory muscles of mastication - the buccinator and digastric muscles. The masseter, temporalis, and medial pterygoid muscles elevate the mandible, while the lateral pterygoid depresses the mandible and aids in protrusion along with the medial pterygoid.

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).