TMJ

Question 1

what is temporomandibular joint?

Answer 1

• the articulation of the head of the mandible with the mandibular (glenoid) fossa of squamois region of the temporal bone
• where all muscles of mastication are working

Question 2

why is the condyle smaller than the articular fossa?

Answer 2

being smaller (along with cylindrical head) allows great mobility AND rotational movement

Question 3

posterior vs anterior compartment

Answer 3

• anterior= mandibular fossa

* posterior= tympanosquamosal fissure, petrotympanic fissure

Question 4

synovial joint

Answer 4

• -united by articular capsule composed of outer fibrous layer and inner serous synovial membrane
• -capsule makes joint unique
• -joint cavity is filled with lubricating synovial fluid secreted by the synovial membrane

Question 5

what lines the bones in contact in synovial joint?

Answer 5

articular cartilage

Question 6

over time what happens to joint?

Answer 6

articular cartilage wears down and membrane produces less fluid

Question 7

name for the TMJ joint based on movement?

Answer 7

ginglymoarthrodial joint

Question 8

TMJ movements

Answer 8

1) hinge =ginglymoid (depress and elevate)

2) glide = arthrodial aka plane (protract, retract, laterally swivel)

Question 9

why is TMJ considered a complex synovial joint?

Answer 9

bc it is an articular joint with a DISC (most don’t have a disc)

Question 10

what compartment of TMJ has what specific movement?

Answer 10

• superior = gliding (translational) movement

* inferior= hinge (rotational) movement

Question 11

Hiltons law

Answer 11

any nerve that is passing by a joint, will give off branches to innervate that joint

Question 12

TMJ innervation from?

Answer 12

V3

Question 13

TMJ innervation and BS?

Answer 13

1) superficial temporal and branches (lateral)

2) maxillary artery and bracnhes (medial)

Question 14

joint capsule

Answer 14

completely encloses the joint

highly vascularized and innervated (receives all blood and nerves)

Question 15

temporomandibular ligament

Answer 15

prevent posterior dislocation
anterior to capsule
temporal zygo arch to neck of mandible

Question 16

stylomandibular ligament

Answer 16

helps limit anterior protrusion of mandible

styloid process down to angle of mandible

Question 17

phenomandibular ligament

Answer 17

may act as pivot and limit protrusion

most frequently DAMAGED in IAN block (trismus=pain)

Question 18

what is important for preventing dislocation posterioly?

Answer 18

the amount of boney structures behind mandibular fossa

Question 19

what is important about the lateral pterygoid muscle being attached to joint capsule AND pterygoid fovea AND head of mandible?

Answer 19

1) prime protractor

2) makes sure articular disc moves with mandibular anteriorly (bc don’t want bone on bone contact)

Question 20

mouth closed starting position

Answer 20

0 degrees

mouth closed, teeth in occlusion

Question 21

first movement ofTMJ

Answer 21

• rotational hinge motion in lower compartment
• *up to 20mm
• head of mandible remains in mandibular fossa, only tilts down

Question 22

second movement of TMG

Answer 22

• translation gliding movement
• head of mandible does NOT stay in fossa
• you Must already be depressed 15-20 in -order to glide open/wide
• superior compartment motion

Question 23

what depresses TMJ (opens mouth)

Answer 23

1) gravity *prime
2) supra/infra hyoid muscles
3) inferior head of lateral pterygoid

Question 24

what elevates TMJ (closes mouth)

Answer 24

1) temporalis

2) masseter and medial pterygoid

Question 25

what does protrusion of TMJ (protracting chin)

Answer 25

1) lateral pterygoid
2) masseter and medial pterygoid
* use head of mandible

Question 26

what does retrusion of TMJ (retracting chin)

Answer 26

1) temporalis
2) masseter
* pulling coronoid process

Question 27

chewing is what motion?

Answer 27

• Circular

* Contraction of ipsilateral retractors and contralateral protractors

Question 28

subluxation of the TMJ

Answer 28

• dislocation of jaw
• anterior is common
• posterior in uncommon due to bone, head of mandible will break before you dislocate

Question 29

lock jaw

Answer 29

• Going past anterior eminence

- (normal open jaw has head on top of eminence)