Muscles of mastication & Temporomandibular Joint - Lecture by Dr.N.Mugunthan.

1. Lecture By
Dr.N.Mugunthan.MBBS,MS,DNB,MNAMS,PhD,MBA(Hosp.Adm.),
Associate Professor
MGMC&RI

2. Learning Objectives
• Muscles of mastication
1. Masseter
2. Temporalis
3. Lateral pterygoid
4. Medial pterygoid
• Temporomandibular joint (TMJ)
• Applied anatomy
©Dr.N.Mugunthan

3. Move the mandible during
mastication and speech
1. Masseter
2. Temporalis
3. Lateral pterygoid
4. Medial pterygoid
Developed from 1st
branchial arch
Supplied by mandibular
nerve
Muscles of mastication
©Dr.N.Mugunthan

4. Masseter muscle
©Dr.N.Mugunthan

5. Masseter muscle
 Quadrilateral in shape
 Covers lat. surface of
ramus of mandible
Has 3 layers
1. Superficial layer
2. Middle layer
3. Deep layer
©Dr.N.Mugunthan

6. Origin:
Superficial layer:
ant.2/3 lower border of
zygomatic arch,
zyg.process of maxilla
Middle layer:
ant.2/3 of deep surface &
post.1/3 of lower border of
zygomatic arch
Deep layer:
deep surface of zygomatic
arch
Masseter muscle cont…
©Dr.N.Mugunthan

7. • Insertion:
Lateral surface of ramus of
mandible
( superficial layer – lower
part, middle layer – middle
part & deep layer in the
upper part)
• Nerve supply :
Masseteric branch of
mandibular nerve (anterior
division)
• Action:
Elevation of mandible
(close the mouth)
Masseter muscle cont…
©Dr.N.Mugunthan

8. Temporalis muscle cont…
©Dr.N.Mugunthan

9. Temporalis muscle
Fan shaped
Fills temporal fossa
Origin:
Temporal fossa & fascia
covering temporalis muscle
Insertion:
Margin & deep surface of
coronoid process
Ant.border of ramus of
mandible
©Dr.N.Mugunthan

10. Nerve supply:
Temporal branches(2) from
anterior division of
mandibular nerve
Action:
• Elevates the mandible
(close the mouth)
• Post.fibres retract the
protruded mandible
Temporalis muscle cont…
©Dr.N.Mugunthan

11. Lateral pterygoid muscle
©Dr.N.Mugunthan

12. Lateral pterygoid muscle cont…
Short muscle
Conical shape
Muscle is surrounded by
pterygoid plexus of veins
Has 2 heads
1. Upper head (small)
2. Lower head (large)
Origin:
• Upper head :
Infratemporal surface &
crest of greater wing of
sphenoid
• Lower head:
Lateral surface of lateral
pterygoid plate ©Dr.N.Mugunthan

13. Insertion:
Pterygoid fovea (ant.surface of neck
of mandible)
Ant.margin of articular disc &
capsule of TMJ
Nerve supply :
A Branch from anterior division of
mandibular nerve
Action:
• Depress the mandible ( open the
mouth)
• Protrude the mandible
• Side to side movements -grinding
action (with opp. Medial pterygoid
turn the chin to same side)
Lateral pterygoid muscle cont…
©Dr.N.Mugunthan

14. Lateral pterygoid muscle cont…
©Dr.N.Mugunthan

15. Key muscle of infra temporal
fossa
Relations:
Superficial:
Masseter
Ramus of mandible
Tendon of temporalis
Maxillary artery
Deep :
Mandibular nerve
MMA
Sphenomandibular lig.&
Deep Head of medial
pterygoid
Relations of lateral pterygoid muscle
©Dr.N.Mugunthan

16. Structures emerging from
Upper border:
Deep temporal nerves
Masseteric nerve
Structures emerging from
Lower border:
Lingual nerve
Inferior alveolar nerve
MMA (passes upwards)
Structures passing between
Two heads:
Maxillary artery (enter)
Buccal branch of mandibular
nerve (comes out)
Relations of lateral pterygoid muscle cont…
©Dr.N.Mugunthan

17. Relations of lateral pterygoid muscle cont…
©Dr.N.Mugunthan

18. Medial pterygoid muscle
©Dr.N.Mugunthan

19. Medial pterygoid muscle
Quadrilateral in shape
Has 2 heads
1. Superficial head
2. Deep head
Origin:
Superficial head:
Tuberosity of maxilla
Deep head:
Medial surface of lateral
pterygoid plate
©Dr.N.Mugunthan

20. Insertion:
• Medial surface of angle &
adjoining ramus of mandible
Nerve supply:
• Nerve to medial pterygoid –
branch from main trunk of
mandibular nerve
Action:
• Elevates the mandible (close
the mouth)
• Protrusion of mandible
• Side to side movements –
grinding action ( with
opp.lateral pterygoid turn the
chin to opp.side)
Medial pterygoid muscle cont…
©Dr.N.Mugunthan

21. Superficial relations:
Upper part of muscle
separated from lateral
pterygoid by
• Lateral pterygoid plate
• Lingual nerve
• Inferior alveolar nerve
Upper part of muscle separated
from ramus of mandible by
• Above mentioned 2 nerves ,
• Maxillary artery &
Sphenomandibular ligament
Superficial relations of medial pterygoid
muscle
©Dr.N.Mugunthan

22. Deep relations of medial pterygoid muscle
Tensor veli palatini
muscle
Superior constrictor
muscle of pharynx
Styloglossus muscle
Stylopharyngeus
muscle
©Dr.N.Mugunthan

23. Deep relations of medial pterygoid muscle
cont…
©Dr.N.Mugunthan

24. Temporomandibular joint (TMJ)
Type : synovial joint
Variety : condylar
Articular surface:
• Upper – articular eminence
& mandibular fossa of
temporal bone
• Lower – head of mandible
 Articular surface covered
with fibrocartilage ©Dr.N.Mugunthan

25. TMJ - Articular surface
©Dr.N.Mugunthan

26. TMJ - Articular surface cont…
©Dr.N.Mugunthan

27. • Joint cavity divided into 2
compartment by articular
disc
• Upper : menisco-
temporal compartment
• Lower : menisco-
mandibular compartment
TMJ cont…
©Dr.N.Mugunthan

28. Ligaments
1. Fibrous capsule
2. Temporomandibular
ligament (lateral lig.)
3. Sphenomandibular
ligament
4. Stylomandibular
ligament
©Dr.N.Mugunthan

29. Articular disc
Degenerated insertion of
lateral pterygoid
Oval shape
Fibrocartilage
Divide the joint into upper
menisco-temp (gliding
movement) and lower
menisco-mandibular (gliding
& rotatory movement)
compartment
Periphery of disc attached to
capsule
Disc has ant.extension,
ant.thick band, intermediate
zone, post.thick band &
bilamellar region
©Dr.N.Mugunthan

30. Relations
• Anterior - lat.pterygoid &
masseteric nerve & vessels
• Posterior – parotid
gland,superficial
temp.vessels &
auriculotemporal nerve
©Dr.N.Mugunthan

31. • Medial - tympanic plate,
spine of
sphenoid,auriculotemp &
chordatympanic nerve,
middle meningeal artery
• Lateral – skin,
parotidomasseteric fascia,
parotid gland & temp.
branch of facial nerve
Relations cont…
©Dr.N.Mugunthan

32. • Superior – middle cranial
fossa, middle meningeal
artery
• Inferior –maxillary
vessels
Relations cont…
©Dr.N.Mugunthan

33. Blood supply
Arterial supply:
• Maxillary artery
• Superficial temporal
artery
Venous drainage:
• Corresponding veins
©Dr.N.Mugunthan

34. Nerve supply
• Auriculotemporal nerve
• Masseteric nerve
©Dr.N.Mugunthan

35. Movements of mandible
Depression – opening of mouth
Elevation – closing of mouth
Protrusion – forward movement
Retraction – backward movement
Side to side or lateral movements
©Dr.N.Mugunthan

36. Muscles producing movements of mandible
Depression (gravity
muscles)– lateral pterygoid
Elevation (antigravity
muscles)–
masseter,temporalis & medial
pterygoid
Protrusion – lateral &
medial pterygoid
Retraction – post.fibres of
temporalis
Side to side or lateral
movements - lateral &
medial pterygoid ( left.lateral
pterygoid with right medial
pterygoid turn the chin to left
side & vice versa)
©Dr.N.Mugunthan

37. Applied anatomy
• Trismus (spasm of
muscles of mastication)
• Locked jaw (masseter
spasm)
• Dislocation/subluxation
• Injury to articular disc
©Dr.N.Mugunthan

38. Summary
• Muscles of mastication
1. Masseter
2. Temporalis
3. Lateral pterygoid
4. Medial pterygoid
• Temporomandibular joint
(TMJ)
• Applied anatomy
©Dr.N.Mugunthan

39. If any queries click @ dr.mugunth111@gmail.com