TMJ

Question 1

What bones make up the TMJ?

Answer 1

Articulation of mandibular condyle and mandibular fossa of temporal bone

Question 2

What is the purpose of the articular disc at the TMJ?

Answer 2

1. Disc is biconcave allow convex surfaces to remain congruent throughout ROM
2. Increases stability
3. Minimizes loss of mobility
4. Reduces Friction
5. Decreases biomechanical stress

Question 3

What kind of joint is the inferior TMJ?

Answer 3

Simple hinge joint

Question 4

What kind of joint is the superior TMJ?

Answer 4

Functions as a gliding joint

Question 5

What attaches to the articular disc?

Answer 5

1. Medial/lateral poles of condyle
2. Anteriorly - Joint capsule and lateral pterygoid
3. Posteriorly - bilaminar retrodiscal pad

Question 6

What does the superior lamina assist the disc with?

Answer 6

Assists the disc in translating anteriorly with mandibular depression

Question 7

What does the inferior lamina do?

Answer 7

Limits forward translation

Question 8

What is the make up of the joint capsule of the TMJ? Where is it strong? Where is it weak? How does those strength and weaknesses influence dislocations?

Answer 8

1. Firm medially/laterally
2. Thin and loose anterior/posterior
   - Allows for ant translation when mouth is open
   - Predisposes TMJ to ant dislocation due to lack of strength of ant capsule and the incongruence of articular surfaces

Question 9

What are the ligaments of the TMJ? What purpose do they serve?

Answer 9

1. Lateral lig - stabilize lateral portion of capsule
2. Stylomandibular lig - weakest of 3
3. Sphenomandibular lig - swinging hinge that suspends manidle

Question 10

What is the normal resting position of the TMJ?

Answer 10

• Lips closed and teeth several mm a part

- Maintained by temporalis muscle

Question 11

]What are the different movements osteokinematically?

Answer 11

• Depression/elevation
• Protrusion/Retrusion
• Left & Right lateral excursion

Question 12

How and at which part of the joint does the first part of mouth opening occur?

Answer 12

Roll posterior in lower joint

Question 13

How and at which part of the joint does the second part of mouth opening occur?

Answer 13

Glide ant in upper joint

Question 14

How and at which part of the joint does the first part of mouth closing occur?

Answer 14

Glide post in upper joint

Question 15

How and at which part of the joint does the second part of closing opening occur?

Answer 15

Roll posterior in lower joint

Question 16

What happens with the articular disc during mouth opening and closing?

Answer 16

50% rolling in lower joint = disc remains stationary

50% gliding in upper joint = disc slides along with condyle

Question 17

How and at which part of the joint does protraction and retraction occur?

Answer 17

Protraction - anterior/slight inferior glide of condyle/disc

Retraction - post/slight superior glide of condylde/disc

Question 18

What happens with the articular disc during protraction and retraction?

Answer 18

Same as condyle

Question 19

What occurs on the ipsilateral side during lateral excursion?

Answer 19

Glide posterior (retrude)

Question 20

What occurs on the contralateral side during lateral excursion?

Answer 20

Glide anterior (protrude)

Question 21

What muscles and forces act on the TMJ during opening?

Answer 21

• Primarily gravity
• Digastric
• Suprahyoids
• Inferior lateral pterygoid

Question 22

What muscles and forces act on the TMJ during Closing?

Answer 22

• Temporalis
• Masseter
• Medial pterygoids
• Control of disc via superior lateral pterygoids

Question 23

What muscles and forces act on the TMJ during Protrusion?

Answer 23

• Superior masseters
• Medial Pterygoids
• Lateral Pterygoids

Question 24

What muscles and forces act on the TMJ during Retrusion?

Answer 24

• Post. Fibers: Temporalis
• Deep Fibers: Masseter
• Ant. Digastric (some help)

Question 25

What muscles and forces act on the TMJ during Lateral excursion?

Answer 25

- Contralateral Med/Lat Pterygoid (pull condyle forward) | - Ipsilateral Temporalis (pull condyle posterior)

Question 26

What is the normal ROM for the different motions of the TMJ?

Answer 26

1. Opening: 35-50 mm -(25-35 mm: needed for everyday activity) -Functional screen of mandibular depression 2 knuckles=functional 3 knuckles=normal 2. Lateral deviation: 10-15mm 3. Protrusion: 3-9 mm 4. Retrusion: about 3 mm

Question 27

What is TMD?

Answer 27

- Broad/vague term used to describe dysfunctions associated with TMJ - Includes pain, popping, reduced bite force, reduced ROM with mouth opening, headaches, tinnitus trigger points

Question 28

What factors are associated with TMD?

Answer 28

- Stress/emotional disturbance - Daily oral parafunctional habits - Asymmetric muscle activity - Sleep bruxism - Chronic forward head posture - C-spine pathology - Sensitization of the CNS

Question 29

What is deviation of TMJ?

Answer 29

Motion that produces "S" curve with depression or protrusion

Question 30

What is deflection of TMJ?

Answer 30

Motion that produces "C" curve with depression or protrusion

Question 31

Describe what is occurring during mouth opening/closing when there is a disc displacement with reduction? Why is there a click? What is a reciprocal click?

Answer 31

- Full opening - Disc sits anterior - Reciprocal Click: opening click as disc relocates, closing click as disc gets squeezed abnormally & subluxes anteriorly

Question 32

Describe what is occurring during mouth opening/closing when there is a disc displacement without reduction? Why is there not a click?

Answer 32

- Closed lock/no clicking - Partial anterior displacement or dislocation - Mandibular condyle unable to pass over the posterior border of the disc with opening (disc remains bunched anterior to the mandibular condyle) - Disc does not relocate: Blocks translation and limits motion - Deviation toward painful side during opening

Question 33

How does posture and the cervical spine impact the TMJ?

Answer 33

- may affect tension in cervical muscles which can influence the function of the mandible - Forward head = posterior/superior position -> greater stress on TMJ, lateral pterygoid contracture, anterior disk displacement