Occlusion 1

Question 1

What is the TMJ

Answer 1

a joint between the condylar head of the mandible and the mandibular fossa of the temporal bone

Question 2

What type of joint is the TMJ

Answer 2

synovial

condylar hinge type joint

Question 3

What type of surfaces does the TMJ have

Answer 3

fibrocartilaginous surfaces and an articular disc that divides the joint into 2 halves

Question 4

What muscle is attached to the articular disc

Answer 4

lateral pterygoid

Question 5

What is the mandibular fossa

Answer 5

an indentation in the cranial base

Question 6

What is the capsule

Answer 6

a fibrous membrane that surrounds the joint and attaches to the articular eminence, articular disc and the neck of the mandibular condyle

Question 7

What is the articular disc

Answer 7

it is a fibrous extension of the capsule that runs between 2 articular surfaces of the TMJ

the disc articulates with the mandibular fossa and the condyle of the mandible below

disc divided the joint into 2 sections each with its own synovial membranes and there are synovial spaces and membranes above and below

Question 8

What is the disc attached to medially, anteriorly, posteriorly and laterally

Answer 8

medially - condyle
laterally - lateral ligaments
anteriorly - joint capsule and superior head of the lateral pterygoid
posteriorly - mandibular fossa (referred to as the retrodiscal tissue)

Question 9

Why is the retrodiscal tissue more responsible for pain

Answer 9

it is more vascular

Question 10

What are the function of the muscles of mastication

Answer 10

involved in depression, elevation, and lateral movements of the mandible

Question 11

What is the function of the supra hyoid muscles

Answer 11

elevate the hyoid bone or depress the mandible

Question 12

What is the function of the temporalis

Answer 12

elevates and retracts the mandible and assists in rotation

Question 13

What is the function of the lateral pterygoid

Answer 13

positions disc in closing (superior - SLP)

protrudes and depresses the mandible and causes lateral movement (inferior - ILP)

Question 14

What is the function of the medial pterygoid

Answer 14

elevates the mandible

lateral movement and protrusion

Question 15

What is the function of the masseter (SMA)

Answer 15

elevates and protracts the mandible

assists in lateral movement

Question 16

What are the mandibular movements

Answer 16

rotation

translation (lateral translation is grouped under this too)

Question 17

What is rotation

Answer 17

small amount of mouth opening (up to 20mm)

Question 18

What happens in rotation

Answer 18

the condyle and disc remain within the articular fossa
no downwards or forwards movement
aka hinge movement

Question 19

What is hinge movement

Answer 19

it is the rotation of the condylar heads around an imaginary horizontal line through the rotational centre of the condyles

Question 20

What is the name given to the imaginary line in hinge movement

Answer 20

terminal hinge axis

Question 21

What does a face bow record

Answer 21

the terminal hinge axis

the distance between condyles

Question 22

What does the face bow allow

Answer 22

it allows us to ensure that we get as accurate a relationship as possible to that in the mouth when mounting the maxillary casts

Question 23

What happens in translation of the condyle

Answer 23

the lateral pterygoid contracts
the articular disc and condyle begin to move
the condyle travels downwards and forwards along the incline of the articular eminence
may also travel laterally (laterotrusive movement)

Question 24

What is Posselt’s envelope

Answer 24

it is the extremes of mandibular movmenet

it shows the border movements of the mandible in the SAGITTAL PLANE

Question 25

What is the order of the envelope starting with ICP and going clockwise

Answer 25

``` ICP E Pr T R RCP ```

Question 26

What is ICP

Answer 26

intercuspal position

Question 27

What is E

Answer 27

edge to edge

Question 28

What is Pr

Answer 28

protrusion

Question 29

What is T

Answer 29

maximum opening

Question 30

What is R

Answer 30

retruded axis position

Question 31

What is RCP

Answer 31

retruded contact position

Question 32

What is ICP

Answer 32

``` it is the tooth position regardless of the condylar position the comfortable bite best fit of the teeth maximum interdigitation of the teeth can be called centric occlusion ```

Question 33

What is edge to edge

Answer 33

it is a tooth position the teeth slide forward from ICP guiding on palatal surfaces of anterior teeth incised edges of upper and lower incisors touch

Question 34

What is protrusion

Answer 34

the condyles move forwards and downwards on the articular eminence only incisors and maybe canines touch there should be no posterior tooth contacts eventually there should be no tooth contacts

Question 35

What is T

Answer 35

no tooth contacts mouth wide open full translation of the condyle over the articular eminence

Question 36

What is retruded axis position

Answer 36

no tooth contacts most superior anterior position of the condylar head in the fossa terminal hinge axis

Question 37

What is the retruded contact position

Answer 37

first tooth contact when the mandible is in the retruded axis position ICP is approximately 1mm anterior to the RCP in 90% of the population

Question 38

Are Rcp and ICP coincident

Answer 38

no | mandible slides forward to achieve ICP

Question 39

What is the working side in lateral translation

Answer 39

the side that the mandible is going to

Question 40

What is the non working side

Answer 40

the side that the mandible is going away from

Question 41

What is lateral translation of the mandible known as

Answer 41

Bennet movement

Question 42

What is lateral movement a result of

Answer 42

contraction of the lateral pterygoid on one side

Question 43

What is Bennet Angle

Answer 43

The path of the nonworking condyle in the horizontal plane during lateral excursion

Question 44

What is bennet movement

Answer 44

The bodily lateral movement or lateral shift of the mandible resulting from the movements of the condyles along the lateral inclines of the mandibular fossae in lateral jaw movements