TMJ & Muscles of Mastication

Question 1

function of mandible with regard to muscles

Answer 1

site of attachment for muscles

Question 2

what joins to form the mandible

Answer 2

a vertical ramus and horizontal body

Question 3

2 processes of the mandibular body

Answer 3

coronoid process and condylar process

Question 4

what is the condylar process

Answer 4

the articular process of the TMJ that consists of a head and neck

Question 5

what is found between the 2 processes

Answer 5

the mandibular notch

Question 6

what is the angle of the mandible

Answer 6

where the ramus and body meet posteriorly

Question 7

what forms the prominent part of the chin

Answer 7

mental protuberance

Question 8

what exits the mental foramen

Answer 8

mental nerve and associated blood vessels

Question 9

what is the mandibular symphysis

Answer 9

where the 2 parts of the mandible fuse during development

Question 10

what exits the mandibular foramen

Answer 10

the inferior alveolar nerve and accompanying artery and vein enter into the mandibular canal within the bone via this

Question 11

what muscles attach to the mandible medially

Answer 11

mylohyoid and medial pterygoid

Question 12

what muscles attach to the mandible inferiorly

Answer 12

infrahyoid muscles i.e. sternohyoid, sternothyroid, thyrohyoid, omohyoid

Question 13

what muscles attach to the mandible laterally

Answer 13

masseter

Question 14

what provides the boundary between the oral cavity and the neck

Answer 14

mylohyoid line and mylohyoid raphe

Question 15

what happens if an abscess spreads below the mylohyoid line

Answer 15

it can cause Ludwig’s angina

Question 16

why is mylohyoid line important in dentures

Answer 16

must stop short of mylohyoid muscle as contraction of it will move the denture when eating or speaking

Question 17

why is the buccinator important in dentures

Answer 17

denture must stop short of oblique line otherwise buccinator will interfere with denture

Question 18

mylohyoid groove

Answer 18

this is where the nerve to mylohyoid passes which is a branch of the inferior alveolar nerve which supplies the mylohyoid and digastric

Question 19

where does the mandible articulate with the skull

Answer 19

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

Question 20

what forms the TMJ

Answer 20

the mandibular fossa of the temporal bone and condylar process of the mandible

Question 21

what is the TMJ

Answer 21

a modified hinge (atypical) synovial joint

Question 22

articular surfaces of TMJ are covered in

Answer 22

fibrocartilage NOT hyaline cartilage

Question 23

what is unique about the TMJ

Answer 23

it is intrinsically unstable joint with anterior dislocation most common

Question 24

2 extrinsic ligaments of TMJ

Answer 24

sphenomandibular and stylomandibular

Question 25

name the 3 ligaments of TMJ

Answer 25

1. sphenomandibular ligament 2. stylomandibular ligament 3. lateral ligament

Question 26

intrinsic ligament of TMJ

Answer 26

lateral ligament

Question 27

sphenomandibular ligament

Answer 27

primary passive support of the mandible. runs from spine of sphenoid to lingula of mandible

Question 28

stylomandibular ligament

Answer 28

thickening of the fibrous capsule of the parotid gland. runs from styloid process to angle of mandible

Question 29

lateral ligament

Answer 29

strengthens TMJ laterally and acts to prevent posterior dislocation with the postglenoid tubercle

Question 30

when is TMJ most unstable

Answer 30

during depression

Question 31

why is it most unstable during depression

Answer 31

condylar processes move anteriorly & lie underneath the articular eminences with the mandibular head then vulnerable to dislocation into the infratemporal fossa

Question 32

5 movements of TMJ

Answer 32

1. protrusion 2. retraction 3. elevation 4. depression 5. lateral

Question 33

protrusion + retraction =

Answer 33

gliding movements between temporal bone and articular disc (superior cavity)

Question 34

elevation + depression =

Answer 34

hinge & rotational movements of mandible and articular disc (inferior cavity)

Question 35

lateral movements =

Answer 35

grinding & chewing

Question 36

protrusion caused by

Answer 36

lateral pterygoid assisted by medial pterygoid and masseter

Question 37

retraction caused by

Answer 37

posterior fibres of temporalis, deep part of masseter, geniohyoid and digastric

Question 38

elevation caused by

Answer 38

temporalis, masseter, medial pterygoid

Question 39

depression caused by

Answer 39

gravity, digastric, geniohyoid and mylohyoid

Question 40

how does anterior dislocation happen

Answer 40

when head of mandible pass anterior to articular tubercles through excessive contraction of the lateral pterygoids

Question 41

lateral movement caused by

Answer 41

temporalis of same side, pterygoids of opposite side and masseter

Question 42

nerve supply of muscles of mastication

Answer 42

CN V3 i.e. mandibular division of the trigeminal

Question 43

what are the 4 muscles of mastication

Answer 43

temporalis, masseter, medial pterygoid, lateral pterygoid

Question 44

temporalis origin

Answer 44

temporal fossa & fascia

Question 45

temporalis insertion

Answer 45

coronoid process of mandible (medial surface) anterior border of ramus near last molar

Question 46

temporalis function

Answer 46

retracts and elevates the mandible i.e. assists in closing the mouth

Question 47

innervation of temporalis

Answer 47

deep temporal nerves from anterior trunk of CN V3

Question 48

masseter origin

Answer 48

maxillary process of zygomatic bone anterior 2/3s of inferior border of zygomatic arch (superficial head)

Question 49

masseter insertion

Answer 49

at angle and lateral surface of the ramus of the mandible (superficial head)

Question 50

masseter function

Answer 50

quadrate muscle that elevates the mandible

Question 51

masseter innervation

Answer 51

masseteric nerve from anterior trunk of CN V3

Question 52

medial pterygoid origin

Answer 52

from medial surface of lateral pterygoid (deep head) maxillary tuberosity and pyramidal process of palatine bone (superficial head)

Question 53

medial pterygoid insertion

Answer 53

inserts into medial surface of ramus and angle of mandible

Question 54

medial pterygoid function

Answer 54

elevates mandible and assists with lateral movements. also acts synergistically with masseter

Question 55

medial pterygoid

Answer 55

quadrangular 2 headed muscle with a deep and superficial head

Question 56

medial pterygoid innervation

Answer 56

by nerve to medial pterygoid from anterior trunk of CN V3

Question 57

lateral pterygoid origin

Answer 57

infratemporal surface of greater wing of sphenoid bone (upper head) lateral surface of lateral pterygoid plate (lower head)

Question 58

lateral pterygoid insertion

Answer 58

inserts on to front of the neck of the mandible: - pterygoid fovea for inferior head - capsule of TMJ and articular disc for superior head

Question 59

lateral pterygoid function

Answer 59

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

Question 60

lateral pterygoid innervation

Answer 60

by nerve to lateral pterygoid & buccal nerve from anterior trunk of CN V3