craniomandibular biomechanics

Question 1

What is the lower portion of the complex and what type of joint is it?

Answer 1

• Mandibular condyle and the inferior surface of the articular disc
• Hinge joint

Question 2

What is the upper portion of the complex and what type of joint is it?

Answer 2

• Temporal bone and the superior surface of the articular disc
• Amphiarthrodial (plane) joint

Question 3

What is the primary movement of the lower potion

Answer 3

rotation

Question 4

What is the primary movement of the upper potion

Answer 4

translation

Question 5

how many degrees of freedom does TMJ have

Answer 5

3 degrees of freedom

• depression/elevation
• protrusion/retrusion
• lateral excursion

Question 6

arthokinematics: depression (opening)

Answer 6

1st part (lower): - Anterior Roll (Rotation) 
2nd part (upper): - anterior and inferior glide (Translation)

Question 7

arthokinematics: elevation (closing)

Answer 7

1st part (upper): Posterior and superior glide (translation)
2nd part (lower): posterior roll (rotation)
NOTE: upper is active first!

Question 8

arthokinematics: left lateral deviation

Answer 8

ipsilateral- pivot/rotate toward left side

contralateral-slide/glide anteriorly and pivot/rotate to the left (medial pivot/rotation)

Question 9

arthokinematics: right lateral deviation

Answer 9

ipsilateral- pivot/rotate toward right side

contralateral-slide/glide anteriorly and pivot/rotate to the right (medial pivot/rotation)

Question 10

arthokinematics: protrusion tmj

Answer 10

anterior glide

Question 11

arthokinematics: retrusion tmj

Answer 11

posterior glide

Question 12

ROM of TMJ

Answer 12

depression: 40-55 mm
protrusion: 3-6 mm
retrusion: 3-4 mm
lateral excursion: 10-12 mm

Question 13

TMJ arthrokinematics (closed, open, capsular pattern)

Answer 13

closed: full occlusion (teeth touching)
Open: teeth separated by 2-3 mm
capsular pattern: inferior glide restricted

Question 14

How much ROM (in millimeters) do you need to eat?

Answer 14

18 mm