Head and Neck 2 - TMJ

Question 1

Which joint is the only joint in the body that partially dislocates every time you use it?

Answer 1

Temporomandibular joint (TMJ)

Question 2

What can cause a higher incidence of TMJ dysfunction?

Answer 2

Anxiety and sleep disorders

Question 3

Describe the mandible

Answer 3

Formed by a union, in the midline, of 2 halves each having a horizontal body and a vertical ramus

Question 4

Where is the angle of the mandible?

Answer 4

Where the body and ramus meet

Question 5

Which 2 processes are at the superior end of the ramus?

Answer 5

Coronoid process

Condylar process/head of condoyle

Question 6

Which is the only muscle that opens the mouth?

Answer 6

Lateral pterygoid muscle

Question 7

When does the mandible fuse?

Answer 7

In-utero

Question 8

Where is the mental foreman located and which nerve passes through here?

Answer 8

In the body of the mandible

Mental nerve

Question 9

Where is the mandibular fossa located?

Answer 9

On the temporal bone

Question 10

Where is the articular tubercle located?

Answer 10

The squamous part of the temporal bone

Question 11

What type of joint is the TMJ?

Answer 11

Synovial joint of the condyloid type - modified hinge joint

Question 12

What type of cartilage covers the articular surface of the TMJ?

Answer 12

Fibro-cartilage - usually hyaline cartilage

Question 13

Which structure within the capsule divides the the cavity into superior and inferior compartments?

Answer 13

Fibrocartilaginous disc

Question 14

Describe the articular disc

Answer 14

• A fibrocartilaginous disc
• Margins are attached to the capsule
• Divides the compartment into superior and inferior compartments
• Concave undersurface and concavoconvex upper surface - jockey’s cap

Question 15

Which compartment allows 1) gliding of the TMJ and 2) hinge movement of the TMJ?

Answer 15

1) Upper compartment

2) Lower compartment

Question 16

What are the functions of the TMJ?

Answer 16

Depression: opening the mouth
Elevation of the mandible: closing the mouth
Protrusion: push chin forward
Retraction: move mandible back

Question 17

What is the most common injury of the jaw?

Answer 17

Lockjaw: forward dislocation (jaw sticks out; protrusion)

Question 18

What is the blood supply for the TMJ?

Answer 18

External carotid artery: superficial temporal and maxillary branches

Question 19

What is the nerve supply for the TMJ?

Answer 19

Auriculotemporal and masseteric nerves which are both derived from Vc (mandibular division of the trigeminal nerve)

Question 20

What are the 4 muscles of mastication?

Answer 20

Masseter
Temporalis
Medial pterygoid
Lateral pterygoid

Question 21

Which muscle of mastication is for depression of the mouth?

Answer 21

Lateral pteryoid - the only muscle that opens your mouth

Question 22

What is the function of the medial pterygoid muscle?

Answer 22

Elevation and protrusion of the mandible

Question 23

Where does the medial pterygoid muscle insert?

Answer 23

Arises from the medial surface of the lateral pterygoid plate and inserts onto the medial surface of the angle of mandible and ramus

Question 24

Which structures does the lateral pterygoid muscle insert into?

Answer 24

Arises from infra-temporal surface of the greater wing of sphenoid and lateral surface of the lateral pterygoid plate and inserts into neck of mandible at the fovea and to the capsule an the intra-capsular disc

Question 25

Which muscles protrude the mandible?

Answer 25

Lateral pterygoid (assisted by medial pterygoid)

Question 26

Which muscles retract the mandible?

Answer 26

Posterior fibres of the temporals, deep part of masseter and geniohyoid and digastric

Question 27

Which muscles depress the mandible?

Answer 27

Lateral pterygoid

Gravity, digastric geniohyoid and mylohyoid muscles

Question 28

Which muscles elevate the mandible?

Answer 28

Temporalis, masseter, medial pterygoid