TMJ

Question 1

What does the TMJ consist of?

Answer 1

Glenoid fossa of the temporal bone and the head of the mandibular condyle

Question 2

what is the purpose of synovial membrane in a typical synovial joint?

Answer 2

-fluid to nourish the articular surfaces to reduce friction, cool the joint, remove waste products

Question 3

what are the features of a typical synovial joint?

Answer 3

• Capsule to enclose joint/retain fluid
• Ligaments to strengthen joint
• Skeletal muscles to move joint

Question 4

In a TMJ, what are the articular surfaces made of?

Answer 4

Fibrous tissue

Question 5

In a TMJ, what is the temporal bone covered in?

Answer 5

periosteum

Question 6

what is the intra-articular disc made of?

Answer 6

dense fibrous tissue

Question 7

what is the head of the mandibular condyle covered in?

Answer 7

perichondrium

Question 8

what lies anteriorly to the TMJ and whats its function?

Answer 8

articular tubercle - prevents anterior dislocation of the TMJ

Question 9

what lies posteriorly to the TMJ?

Answer 9

post-glenoid tubercle-prevent posterior dislocation of the TMJ

Question 10

what aids the post glenoid tubercle in preventing posterior dislocation?

Answer 10

ligaments

Question 11

Where does the lateral pterygoid attach?

Answer 11

pterygoid fovea

Question 12

What nerve goes through the mandibular foreman?

Answer 12

Inferior alveolar nerve

Question 13

where is the retro-molar triangle?

Answer 13

Bind the 3rd molar

Question 14

What is the role of the lateral temporomandibular ligament ?

Answer 14

Stabilising and prevent posterior sublaxation (partial dislocation) and dislocation

Question 15

What does the joint capsule do?

Answer 15

attaches around the circumference of the articular surfaces and keeps synovial fluid in its joint

Question 16

where is the stylomandibular ligament?

Answer 16

styloid process to medial aspect of angle of mandible

Question 17

where is the sphenomandibular ligament and whats its function?

Answer 17

spine of sphenoid to lingual of mandible and it prevents over opening of jaw

Question 18

where is the pterygomandibular raphe and whats his function?

Answer 18

pterygoid hamulus to retromolar triangle and prevents over opening

Question 19

what is the function of the intra-articular disc?

Answer 19

provides stability of the joint during movement by improving the fit between the bony articulating surfaces

Question 20

what is the disc made of?

Answer 20

dense fibrous connective tissue

Question 21

what does the anterior extension of the disc attach to?

Answer 21

continuous with the joint capsule anteriorly and with the tendon of the lateral pterygoid muscle

Question 22

what are the 2 layers of the posterior extension?

Answer 22

• upper layer contains elastic fibres (assist with return of disc to resting position)
• inferior tale- rich blood supply- during jaw opening

Question 23

what happens during jaw opening to fill the space?

Answer 23

both upper and lower layers contain vascular tissue (engorge with blood on opening and empties into pterygoid venous plexus on closing – adapt shape of disc to space available within joint capsule

Question 24

What are the 3 bands of the disc proper?

Answer 24

• anterior band (thick – 3mm)
• intermediate zone (thin - 1mm)
• posterior band (thick – 3mm)

Question 25

what are the join spaces and what are they lined by?

Answer 25

• upper and lower

- lined by its own synovial membrane

Question 26

what happens during initial jaw opening?

Answer 26

anterior rotation of head of condyle
movement occurs in the lower joint space
the disc remains in place

Question 27

what happens during full jaw opening?

Answer 27

disc then translates (slides) anteriorly articulating with the mandibular fossa and articular eminence
the movement occurs in the upper joint space

Question 28

what is the name for a clicking jaw?

Answer 28

internal derangement with reduction

Question 29

what happens during internal derangement with reduction?

Answer 29

• Disk displacement with reduction typically causes clicking and pain with chewing
• Internal derangement is associated with stretching of the posterior extension

Question 30

what is the nerve supply to the TMJ?

Answer 30

auricolotemporal nerve

Question 31

what happens during dislocation of the TMJ?

Answer 31

• occurs when the mandibular condyle becomes fixed in the anterosuperior aspect of the articular eminence
• Spasm of the masseter, temporalis, and internal pterygoid muscles results in trismus, preventing return of the condyle to the temporal fossa

Question 32

what is the movement of jaw opening?

Answer 32

initial anterior rotation (hinge - lower joint space)
subsequent anterior translation (slide - upper joint space)
maximum normal opening equivalent to

Question 33

what is the movement of jaw closing?

Answer 33

initial posterior translation (upper joint space)

subsequent posterior rotation (lower joint space)