Anatomy of Masticatory structures

Question 1

describe the TMJ joint

Answer 1

hinging movements in one plane (ginglymoid joint) and gliding movement in another plan (arthrodial joint)

Question 1

what type of joint is the TMJ

Answer 1

a ginglymoarthrodial joint

Question 2

with initial opening of the TMJ, the condyle _______

Answer 2

rotates or hinges

Question 3

with wide opening the TMJ, ______ movement occurs

Answer 3

translation or gliding

Question 4

the middle of the condyle should reach the summit of the articular eminence with:

Answer 4

maximum opening

Question 5

articulation is between:

Answer 5

the cranium and the mandible

Question 6

what does the TMJ capsule contain

Answer 6

a fibrous capsule contains the synovial fluid and maintains the relationship between the joint components

Question 7

what does the synovial fluid do

Answer 7

transports nutrients to and waste products from the articular surfaces and lubricates joint

Question 8

synovial fluid is secreted by? and how much is in the joint space

Answer 8

the membrane lining the synovial joint and there is approximately 1cc in each compartment of the joint spaces

Question 9

the disc separates what?

Answer 9

the condyle and mandibular fossa from direct contact and divides joint into superior and inferior joint spaces

Question 10

what are the functions of disc

Answer 10

• distributes loading forces
• decreases wear
• stabilizes condylar movement

Question 11

the disc is composed of:

Answer 11

dense fibrous connective tissue NOT cartilage

Question 12

can the disc repair itself

Answer 12

the disc has some ability to repair itself

Question 13

where is the disc devoid of nerves and where does it articulate

Answer 13

in the intermediate zone which articulates with the supererior aspect of the condyle

Question 14

what is the histology of the disc of the TMJ

Answer 14

• dense, fibrous CT
• non vascular in center
• non innervated in center

Question 15

what is the histology of the posterior attachment

Answer 15

• loose, vascular CT
• richly innervated (auriculotemporal nerve)

Question 16

what is the posterior attachment called

Answer 16

retrodiscal tissue

Question 17

the articulating surfaces are lined with:

Answer 17

dense fibrocartilage

Question 18

what is the importance of the dense fibrocartilage lining the articulating surfaces

Answer 18

allows for a greater ability to heal

Question 19

what covers the articulating surface of the bone

Answer 19

a thin layer of cartilage

Question 20

what is the function of the articular cartilage

Answer 20

plays an important role as a stress absorber during function

Question 21

the compressive loading of the articular cartilage is highest in the:

Answer 21

anteromedial region of the condyle

Question 22

what is the articular cartilage composed of

Answer 22

cells and ECM

Question 23

what do discal ligaments do

Answer 23

allow disc to move in anterior posterior direction during condylar translation

Question 24

discal ligaments may become inflamed and painful because:

Answer 24

they are vascularized and innervated

Question 25

what does the maxillary artery supply

Answer 25

medregion of face

Question 26

what do the sphenomandibular ligament and sytlomandibular ligament do

Answer 26

limits inferior movement of mandible

Question 27

what is the vascular supply to the TMJ

Answer 27

- superficial temporal artery: transverse facial - maxillary artery: deep auricular, masseteric, posterior deep temporal

Question 28

what is the nerve supply to the TMJ

Answer 28

- auriculotemporal (V3) nerve - masseteric nerve

Question 29

what are the masticatory muscles

Answer 29

- masseter - medial pterygoid - temporalis - lateral ptyergoid - digastric muscle

Question 30

what muscles work to elevate (close) the mandible

Answer 30

- masseter - medial pterygoid - temporalis

Question 31

what does the lateral pterygoid do

Answer 31

assists in protrusion (inferior head) and stabilizes the disc/condyle complex ( superior head)

Question 32

what does the digastric muscle do

Answer 32

assists in depression (mouth opening) and retrusion

Question 33

what are the functional behaviors of the masticatory muscles

Answer 33

talking, chewing and swallowing

Question 34

what are the nonfunctional behaviors of the masticatory muscles

Answer 34

- bruxism, clenching or empty mouth chewing movements

Question 35

what is the innervation of the masticatory muscles

Answer 35

V3 mandibular nerve

Question 36

what does the superficial masseter muscle do

Answer 36

elevates the mandible (closes the jaw)

Question 37

what does the deep masseter muscle do

Answer 37

retrudes the mandible

Question 38

what are the actions of the temporalis muscle

Answer 38

- closes the jaw - retrudes the jaw (with posterior and middle fibers) - deviates the jaw to the same side

Question 39

what are the actions of the medial pterygoid msucle

Answer 39

- deviates the jaw to opposite side - helps to elevate the mandible in concert with masseter and temporalis muscles - assists the lateral pterygoid in protrusion

Question 40

what does the superior division of the lateral pterygoid muscle

Answer 40

pulls disc forward and check-reins its backwards movement and assists in closing jaw

Question 41

what does the inferior division of the lateral pterygoid muscle do

Answer 41

- protrudes and depresses (opens) the mandible - deviates jaw to opposite side

Question 42

what are the digastric muscle actions

Answer 42

- depresses (opens) and retrudes the mandible

Question 43

what are TMD disorders

Answer 43

a collective term that includes a number of clinical problems that involve the masticatory muscles, TMJ and associated structures

Question 44

what are the 3 TMD groups

Answer 44

- musculoskeletal disorders - articular disc disorders - inflammatory and non inflammatory disorders