Occlusion 2

Question 1

what are the components of occlusion?

Answer 1

• TMJ
• muscle of mastication
• teeth
• nerves
• muscles, ligaments, and bones which affect position of mandible

Question 2

occlusion is described as a what?

Answer 2

tripod where the TMJs are the posterior apices and the teeth are the anterior apex

Question 3

what is the temporomandibular joint anatomically classified as?

Answer 3

bilateral synovial diathrosis-ginglymoid joint

Question 4

what is the articular disc and where does it articulate?

Answer 4

fibrous extention of the capsule that runs between the two articular surfaces of the TMJ

the disc articulates with the mandibular fossa of the temporal bone above and the condyle of the mandible below

Question 5

where is the articular disc attached?

Answer 5

condyle medially and collateral ligaments laterally

anterior disc attaches to the joint capsule and the superior head of the lateral pterygoid

the posterior portion attaches to the mandibular fossa

Question 6

the posterior portion of the articular disc is referred to as what?

Answer 6

retrodiscal tissue

Question 7

what is the capsule and where does it attach?

Answer 7

a fibrous membrane that surrounds the joint

attaches to the articular eminence, the articular disc and the neck of the mandibular condyle

Question 8

TMJ movement is limited by what?

Answer 8

fibrous joint capsule and the boney limits of the glenoid fossa

Question 9

what is the retrodiscal tissue and what does it contribute to?

Answer 9

vascular and highly innervated tissue

major contributor to the pain of temporomandibular disorder particularly where there is inflammation or compression within the joint

Question 10

what is the transverse horizontal axis (hinge axis)? and what is it not based on?

Answer 10

an imaginary line around which the mandible nay rotate within the sagittal plane

very simplified concept of movement not based on the anatomy and physiology of the TMJ

Question 11

what are the principle muscles of mastication?

Answer 11

masseter
temporalis
medial pterygoid (internal)
lateral pterygoid (external)

Question 12

what are the accessory muscles of mastication?

Answer 12

buccinator
digastric
mylohyoid
geniohyoid

Question 13

what are the muscles that close the jaw or position it during closure?

Answer 13

temporalis
massester
medial pterygoid

Question 14

what are the actions of the masseter muscle?

Answer 14

elevation of the mandible
protraction of the mandible (superficial fibers)
retraction of the mandible (deep fibers)

Question 15

what are the actions of the temporalis muscles?

Answer 15

elevation of the mandible
retrusion (pull back) of the mandible (posterior fibers)

Question 16

what would happen if the TMJ was only a hinge joint?

Answer 16

the closing muscles of the jaw would be opposed by the suprahyoid muscles which pull the jaw down

But because of the sliding component of the joint, the opening of the jaw must be assisted by the lateral pterygoid muscle which pulls the condyle forward

Question 17

what are the actions of the medial pterygoid muscles?

Answer 17

elevation of the mandible

protrusion of the mandible (along with lateral pterygoid)

side to side movements of the mandible (chewing) (lateral and medial pterygoid muscles of two sides contract alternately)

Question 18

what are the actions of the lateral pterygoid muscles?

Answer 18

depression of the mandible

protrusion of the mandible

side to side movements of the mandible (chewing) (lateral and medial pterygoid muscles of two sides contract alternately)

Question 19

what happens when there is a bilateral contraction vs a unilateral contraction of the lateral pterygoid?

Answer 19

bilateral contractions will produce protrusion of the jaw

unilateral contractions will produce movement of the jaw to the opposite side