TMJ & Muscles of Mastication

Question 1

Describe the osteology of the mandible

Answer 1

Contains:
- Body of mandible
- Angle of mandible
- Ramus
- Condylar process (Most posterior process)
- Coronoid process (Most anterior process)

Question 2

What contributes to make the TMJ?

Answer 2

• Mandibular fossa of temporal bone
• Condyle process
• Articular disc
• Synovial membrane

Question 3

What are the intrinsic & extrinsic ligaments of the TMJ?

Answer 3

2 Extrinsic
- Sphenomandibular ligament
- Stylomandibular ligament

1 Intrinsic
- Lateral ligament

Question 4

What is the main ligament of the TMJ and its function?

Answer 4

Sphenomandibular ligament and primary passive support of mandible

Question 5

What types of movements can the TMJ allow to occur to the mandible and what muscles assist in them?

Answer 5

• Protrusion (forward) [lateral pterygoid]
• Retraction (backwards) [temporalis & masseter]
• Elevation [temporalis, masseter, medial pterygoid]
• Depression [gravity, digastric, geniohyoid & mylohyoid muscles]
• Lateral movements

Question 6

When is the TMJ most unstable/vulnerable to dislocation?

Answer 6

When its depressed since the condylar process can move anteriorly

Question 7

What are the main 4 muscles of mastication?

Answer 7

Temporalis, masseter, medial & lateral pterygoid

Question 8

What is the nerve supply for the 4 muscles of mastication?

Answer 8

Mandibular division of trigeminal nerve (CN V)

Question 9

What is the action of the temporalis muscle?

Answer 9

Retraction & elevation of mandible

Question 10

What is the action of the masseter muscle?

Answer 10

Elevation of mandible (powerful elevator)

Question 11

what is the action of the medial pterygoid?

Answer 11

Elevation of mandible & assisting with lateral movements (side to side)