Temporomandibular Joint and Muscles of Mastication

Question 1

Temporomandibular Joint
Classification: (3)

Answer 1

• Modified hinge type synovial joint
• Depression & elevation (hinge movements) and protraction &
  retraction (gliding movements)
• No hyaline cartilage on articular surfaces

Question 2

Temporomandibular Joint
Articular surfaces: (3)

Answer 2

• The articular tubercle and mandibular fossa of the temporal bone
• The head of the mandible
• Surfaces covered by fibrocartilage

Question 3

Temporomandibular Joint
Joint capsule: (2)

Answer 3

• Attaches to the articular tubercle and mandibular fossa of the
  temporal bone, and to the neck of the mandible
• The articular surfaces are completely separated by a fibrocartilage articular disc

Question 4

What is the function of the fibrocartilage
articular disc? (5)

Answer 4

o Creates superior and inferior articular cavities
o Assumes the shape of the mandibular head
o Each cavity is lined by its own synovial membrane
o Gliding movements occur between temporal bone and articular disc
o Hinge movements occur in the inferior compartment

Question 5

Ligaments
* lateral ligament-

Answer 5

lateral ligament- thickened part of joint capsule

Question 6

What are the extrinsic ligaments? (2)

Answer 6

o Stylomandibular ligament
- Thickening of the parotid fascia
- Runs form styloid process to the angle of mandible
o Sphenomandibular ligament
- Runs from the spine of the sphenoid to the lingula of the mandible

Question 7

Temporomandibular Joint
Blood supply and innervation: (2)

Answer 7

• Superficial temporal artery
• Auriculotemporal and masseteric branches of CN V3

Question 8

Movement of the mandible:
Elevation (close mouth)
Muscles:

Answer 8

Question 9

Movement of the mandible:
Depression (open mouth)
Muscles:

Answer 9

Question 10

Movement of the mandible:
Protrusion (protrude chin)
Muscles:

Answer 10

Question 11

Movement of the mandible:
Retrusion (retrude chin)
Muscles:

Answer 11

Question 12

Movement of the mandible:
Lateral movements (grinding and chewing)
Muscles:

Answer 12

Question 13

Temporalis
Origin: (2)

Answer 13

Floor of temporal fossa
Deep surface of temporal fascia

Question 14

Temporalis
Insertion: (2)

Answer 14

Medial tip of coronoid process
Anterior border of ramus of mandible

Question 15

Temporalis
Innervation:

Answer 15

Deep temporal br.

Question 16

Temporalis
Main action: (2)

Answer 16

Elevates mandible
Retracts mandible

Question 17

Masseter
Origin: (2)

Answer 17

Superficial layer:
- Inferior border and medial surface of maxillary process of zygomatic
Deep layer:
- zygomatic arch

Question 18

Masseter
Insertion: (2)

Answer 18

Angle of mandible
Lateral surface of ramus of mandible

Question 19

Masseter
Innervation:

Answer 19

Masseteric n.

Question 20

Masseter
Main action: (3)

Answer 20

Elevates mandible
Superficial fibres
protrude mandible

Question 21

Lateral pterygoid
Origin: (2)

Answer 21

Superior head:
- Infratemporal surface and crest of greater wing of sphenoid
Inferior head:
- Lateral surface of lateral pterygoid plate

Question 22

Lateral pterygoid
Insertion: (2)

Answer 22

Superior head:
- Joint capsule and articular disc of joint
Inferior head:
- Pterygoid fovea on neck of mandible

Question 23

Lateral pterygoid
Innervation:

Answer 23

Lateral pterygoid n.

Question 24

Lateral pterygoid
Main Action:

Answer 24

Depresses, protrudes and moves mandible laterally

Question 25

Medial pterygoid
Origin: (3)

Answer 25

Superficial head:
- Tuberosity of maxilla

Deep head:
- Medial surface of lateral pterygoid plate
- Pyramidal process of palatine bone

Question 26

Medial pterygoid
Insertion:

Answer 26

Medial surface of mandible near the angle

Question 27

Medial pterygoid
Innervation:

Answer 27

Medial pterygoid n.

Question 28

Medial pterygoid
Main action:

Answer 28

Elevates, protrudes and moves mandible laterally