TMJ and Muscles of Mastication

Question 1

what are the parts of the mandible

Answer 1

body, ramus, angle, coronoid process, condylar process

Question 2

what is the area between the 2 mandibular processes called

Answer 2

mandibular notch

Question 3

what is the mental protuberance

Answer 3

prominent part of chin

Question 4

what is the mental foramina

Answer 4

foramen for nerves and blood vessels

Question 5

what is the mandibular symphysis

Answer 5

where 2 sides of mandibles fuse

Question 6

where is the mandibular foramina

Answer 6

in the medial side where IAN travels

Question 7

how is the mylohyoid line clinically relevant

Answer 7

if dental infection travels inferior to the line it spreads to floor of mouth and submandibular region causing LUDWIGS ANGINA

dentures also need to stop anterior to the line as it attaches to mylohyoid

Question 8

what is the mylohyoid groove

Answer 8

where the nerve to mylohyoid passes through

Question 9

where does the mandible articulate with the skull

Answer 9

at the mandibular fossa of the temporal bone just anterior to external acoustic meatus

Question 10

what is the TMJ comprised of

Answer 10

mandibular fossa of temporal bone and condylar process of mandible

Question 11

what type of joint is the TMJ

Answer 11

modified hinge synovial joint

Question 12

how is the TMJ an atypical joint

Answer 12

as fibrocartilage covers the bony surfaces instead of hyalinecartilage

Question 13

what are the different cavities of the TMJ

Answer 13

superior and inferior articular cavities

Question 14

what type of dislocation occurs most commonly with the TMJ

Answer 14

anterior dislocation

Question 15

what are the 2 types of ligament in the TMJ and how many of each are there

Answer 15

2 extrinsic and 1 intrinsic

Question 16

what are the 2 extrinsic ligaments of the TMJ

Answer 16

sphenomandibular and stylomandibular

Question 17

what is the intrinsic ligament in the TMJ

Answer 17

lateral ligament

Question 18

what is the function of the sphenomandibular ligament

Answer 18

primary passive support of the mandible, supports movement as acts as fulcrum

Question 19

where does the sphenomandibular ligament attach

Answer 19

spine of sphenoid to lingula on medial side of mandible

Question 20

where does the stylomandibular ligament attach to

Answer 20

styloid process to angle of mandible

Question 21

what is the function of the lateral ligament

Answer 21

strengthens TMJ laterally, prevents dislocation

Question 22

what does the lateral ligament work with to prevent dislocation

Answer 22

postglenoid tubercle

Question 23

when is the TMJ most unstable and why

Answer 23

during depression as condylar processes move anteriorly and lie underneath articular eminences with mandibular head vulnerable to dislocation

Question 24

what are the 5 movements of the mandible

Answer 24

protrusion, retraction, elevation, depression, lateral movements

Question 25

what muscle protrudes the mandible

Answer 25

lateral pterygoid

Question 26

what muscle retracts the mandible and what cavity does it occur in

Answer 26

temporalis, in superior cavity

Question 27

what muscles elevate the mandible and what cavity does it occur in

Answer 27

temporalis, masseter, medial pterygoid, inferior cavity

Question 28

what depresses the mandible and what cavity does it occur in

Answer 28

gravity, suprahyoid, infrahyoid, lateral pterygoid, inferior cavity

Question 29

how do the infrahyoids contribute to the depression of the mandible

Answer 29

they fix/move the hyoid bone to allow suprahyoids to depress the mouth

Question 30

what muscles allow lateral (chewing) movements

Answer 30

temporalis on same side and pterygoids on opposite side

Question 31

when there is no movement, what position is the mandible in

Answer 31

heads in retracted position in mandibular fossa and chin elevated by tone of retractors and elevators

Question 32

what are the gliding movements

Answer 32

protrusion and retraction

Question 33

what happens during dislocation

Answer 33

the mandible slips forward to articular tubercle but slips too far

Question 34

why does dislocation happen

Answer 34

excessive contraction of lateral pterygoids (either yawning/large bite) or a sideways blow to the chin whilst mouth is open

Question 35

what happens once the mandible is dislocated

Answer 35

it remains in a depressed position and cannot close

Question 36

what nerves are of close relationship to the TMJ

Answer 36

facial and auriculotemporal nerves

Question 37

what nerve overlies the TMJ

Answer 37

facial nerve

Question 38

what nerves supply the TMJ

Answer 38

articular branches of the auriculotemporal nerve

Question 39

how do the articular branches of the auriculotemporal nerve get damaged

Answer 39

trauma and rupture of articular capsule or due to surgery

Question 40

what happens if the articular branches of the auriculotemporal nerve get damaged

Answer 40

the jaw is even more lax and unstable

Question 41

what are the muscles of mastication supplied by

Answer 41

CNV3

Question 42

what is the origin and insertion of the temporalis

Answer 42

origin - temporal fossa and fascia insertion - coronoid process of mandible and anterior border of ramus of mandible near last molar

Question 43

what is the function of the temporalis

Answer 43

retracts and elevates mandible

Question 44

what is the temporalis innervated by

Answer 44

deep temporal nerves from anterior trunk of CNV3

Question 45

what is the origin and insertion of the masseter

Answer 45

origin - maxillary process of zygomatic bone and anterior 2/3rd of inferior border of zygomatic arch insertion - angle of lateral surface of ramus of mandible

Question 46

what is the function of the masseter

Answer 46

elevation of the mandible

Question 47

what is the masseter innervated by

Answer 47

masseteric nerve from anterior trunk of CNV3

Question 48

what is the origin and insertion of the medial pterygoid

Answer 48

origin - medial surface of lateral pterygoid plate and maxillary tuberosity and pyramidal process of palatine bone insertion - medial surface of ramus and angle of mandible

Question 49

what is the action of the medial pterygoid

Answer 49

elevates mandible and assists with lateral movements

Question 50

what is the innervation of the medial pterygoid

Answer 50

nerve to medial pterygoid from main trunk of CNV3

Question 51

what is the clinical relevance of the medial pterygoid

Answer 51

when giving an IDB the needle can pierce the medial pterygoid and cause trismus

Question 52

what is the origin and insertion of the lateral pterygoid

Answer 52

origin - infratemporal surface of greater wing of sphenoid bone and lateral surface of lateral pterygoid plate insertion - front of neck of mandible

Question 53

what is the action of the lateral pterygoid

Answer 53

protrudes mandible, assists medial pterygoid with lateral side to side movements and depresses mandible

Question 54

what is the innervation of the lateral pterygoid

Answer 54

nerve to medial pterygoid and buccal nerve from anterior trunk CNV3