Temporamandibular Joint

Question 1

What is the TMJ?

Answer 1

articulation of the condyle of the mandible with the zygomatic part of the temporal bone.

Question 2

What sits on the inferior surface of the zygomatic process?

Answer 2

condyle of the mandible sits in the mandibular fossa.

Question 3

What holds the mandible in the mandibular fossa?

Answer 3

Two humps:
postglenoid tubercle
articular eminence

Question 4

Where is the postglenoid tubercle?

Answer 4

posterior to the mandibular fossa

Question 5

Where is the articular eminence?

Answer 5

anterior to the mandibular fossa

Question 6

What important ligaments holds the TMJ together?

Answer 6

Temporomandibular ligament (lateral ligament)
Sphenomandibular ligament
Stylomandibular ligament

Question 7

Where is the Tempromandibular ligament (lateral ligament) ?

Answer 7

lateral thickening of the temporomandibular joint

capsule,

Question 8

What is the function of the temperomandibular ligament (lateral ligament) ?

Answer 8

acts with the postglenoid tubercle to resist posterior dislocation of the TMJ

Question 9

Where is the Sphenomandibular ligament located?

Answer 9

from the spine of the sphenoid to the lingula of the

mandible

Question 10

What is the purpose of the Sphenomandibular ligament?

Answer 10

This ligament is a swinging hinge for the mandible, serving both as a fulcrum and a check ligament. It also supports the weight of the mandible, along with the temporalis muscle.

Question 11

Where is the Stylomandibular ligament?

Answer 11

from the styloid process to the angle of the mandible,

Question 12

What is the Stylomandibular ligament?

Answer 12

a thickening of the fibrous capsule of the parotid gland.

Question 13

What type of joint is the TMJ?

Answer 13

modified hinge type of synovial jointbetween the head of the condyle of the mandible and the mandibular fossa and articular eminence of the temporal bone.

Question 14

What does the articular disc of the TMJ divide?

Answer 14

temporomandibular joint into two separate joints, each lined by its own synovial membrane and each with a different motion:

Question 15

What are the compartments of the TMJ?

Answer 15

superior

inferior

Question 16

What does the Superior compartment of the TMJ permits?

Answer 16

anteroposterior translation of the mandible.

Question 17

What does the inferior compartment of the TMJ permits?

Answer 17

hinge motions of elevation and depression of the

mandible.

Question 18

What are the three motions of the TMJ?

Answer 18

elevation/depression (open/close),
lateral excursion (side to side),
protrusion/retrusion (protraction/retraction).

Question 19

What are the movements of the TMJ during chewing and speaking?

Answer 19

combination of all three motions

Question 20

What does initial depression of the jaw consist of?

Answer 20

opening just enough to separate the maxillary and mandibular teethoccurs as a hinge motion in the inferior compartment of the TMJ. Elevation of the jaw across this small distance is also a hinge motion.

Question 21

What does depressing the jaw widely consist of?

Answer 21

involves translation of the mandibular condyle and articular disc anteriorly onto the articular eminence. This motion occurs in the superior compartment of the TMJ. The mandibular condyle slides back again into the mandibular fossa in normal jaw closing. This means that for all but minimal elevation/depression, protrusion/retrusion must also occur.

Question 22

What does lateral excursion of the jaw consist of?

Answer 22

unilateral protrusion, which can be accomplished by muscles pulling on the condyle on the same side of the excursion (ipsilateral contraction) or by muscles pulling on the opposite side of the excursion (contralateral contraction).