Oral Biology: TMJ

Question 1

What type of joint is the TMJ?

Answer 1

Synovial

Question 2

Between which two bones is the TMJ located?

Answer 2

Temporal and Mandible

Question 3

The TMJ is capable of hinge and slide movements. What other name is given to a joint that is capable of such movements?

Answer 3

A glinglymoarthroidal joint

Question 4

The TMJ is a unique joint due to it’s 2-compartment joint space - disc. What two things limit it’s movement?

Answer 4

1) The contralateral TMJ

2) Teeth

Question 5

Which fossa of the skull does the condyle of the mandible sit in?

Answer 5

The glenoid fossa (of the temporal bone)

Question 6

What is the structure anterior to the glenoid fossa called?

Answer 6

The articular eminence

Question 7

Which two structures bind in the glenoid fossa?

Answer 7

1) the articular eminence

2) tympanic plate of the temporal bone

Question 8

Is the glenoid fossa thin bone or thick bone?

Answer 8

The glenoid fossa is thin bone - masticatory forces are transmitted through teeth

Question 9

What lies anterior to the external acoustic meatus?

Answer 9

The glenoid fossa

Question 10

How would you describe the condyle? (4)

Answer 10

1) Much variation in shape
2) Usually oval in outline
3) Medial aspect is wider than Lateral aspect
4) Lateral Pole anterior to Medial Pole

Question 11

What type of cartilage does the condyle have on it’s surface?

Answer 11

Fibrous cartilage

Question 12

Describe the Joint Capsule of the TMJ (4)

Answer 12

1) Thin
2) Attached to the Glenoid Fossa
3) Continuous with Disc
4) Has two layers: outer fibrous layer and inner synovial membrane

Question 13

Describe the inner synovial membrane of the joint capsule of the TMJ

Answer 13

1) inner aspect of the joint capsule

2) secretes synovial fluid to fill joint spaces

Question 14

What is the synovial fluid in the inner synovial membrane comprised of? (3)

Answer 14

1) proteoglycans
2) lubricant
3) nutritive

Question 15

Describe the Lateral Ligament (2)

Answer 15

1) essentially part of the joint capsule

2) spans from the lateral surface of the articular eminence to the posterior surface of the condyle

Question 16

What is the function of the Lateral Ligament?

Answer 16

1) restricts posterior, lateral and inferior movement
2) restricts contralateral medial movement
3) limits the extent of a pure hinge movement

Question 17

Name the three accessory ligaments of the TMJ

Answer 17

1) Stylomandibular Ligament
2) Pterygomandibular Raphe
3) Sphenomandibular Ligament

Question 18

What are the 5 zones of the articular disc?

Answer 18

1) anterior extension
2) posterior extension
3) anterior band of disc
4) intermediate zone of disc
5) posterior band of disc

Question 19

What is the articular disc?

Answer 19

The articular disc is a dense, fibrous disc which transmits forces, protects and lubricates the articulating surfaces of the TMJ

Question 20

How many compartments does the articular disc divide into and what are their movements?

Answer 20

The articular disc divides into two compartments:

1) Upper - facilitates slide movements
2) Lower - facilitates hinge movements

Question 21

Describe the two parts of the posterior extension of the articular disc

Answer 21

1) upper layer - vascular and elastin (elastin fibres)
2) lower layer - fibrous

Both layers are densely innervated and vascular

Question 22

Which muscle is the anterior extension of the articular disc continuous with?

Answer 22

The anterior extension is continuous with the superior head of the lateral pterygoid muscle

Question 23

Which cranial nerve supplies the TMJ?

Answer 23

The mandibular division of the trigeminal nerve (CNVc) supplies the TMJ

Question 24

Which part of the TMJ is richly innervated, and which is not?

Answer 24

The joint capsule of the TMJ is richly innervated, but the disc is not.

Question 25

Which two arteries supply the TMJ with blood?

Answer 25

1) superficial temporal artery | 2) maxillary artery

Question 26

Nerve endings in the TMJ: What do the free nerve endings in the TMJ bring about? What do the complex nerve endings in the TMJ bring about?

Answer 26

1) FREE NERVE ENDINGS - bring about nociception (the sensation of pain) 2) COMPLEX NERVE ENDINGS - bring about awareness of movement/posture/position

Question 27

What movement occurs with slight jaw opening?

Answer 27

A simple hinge movement resulting in lower joint space

Question 28

What movements occur with a wide jaw opening?

Answer 28

Hinge and slide movements resulting in an upper joint space between the condyle and the glenoid fossa

Question 29

What movements occur with protrusion of the mandible?

Answer 29

The condyle slides anteriorly leaving an upper joint space between the condyle and the glenoid fossa

Question 30

Describe the bilateral movements of the TMJ when a patient moves their jaw to the right?

Answer 30

Left TMJ: translates laterally | Right TMJ: rotates around vertical axis and therefore moves laterally to the right

Question 31

Describe the bilateral movements of the TMJ when a patient moves their jaw to the left?

Answer 31

Right TMJ: translates laterally | Left TMJ: rotates around vertical axis and therefore moves laterally to the left

Question 32

What kind of displacement can cause pain/problems in the TMJ?

Answer 32

Anterior disc displacement

Question 33

What kind of displacement causes clicking of the TMJ?

Answer 33

Anterior disc displacement with reduction

Question 34

Anatomically describe the dislocation of the TMJ and its resulting effect on the muscles

Answer 34

A TMJ dislocation is when the condyle is anterior to the articular eminence. it causes surrounding muscles spasm.