TMJ

Question 1

Where does the articulating disc of the TMJ lack a blood supply and sensory innervation

Answer 1

Its periphery

Question 2

What is the articular disc’s function?

Answer 2

1. Maximizes joint congruency to reduce contact pressure
2. Adds stability to the joint
3. Helps guide the mandibular condyle

Question 3

The posterior region of the articular disc is [convex/concave] superiorly and [convex/concave] inferiorly.

Answer 3

convex; concave

Question 4

What is the retrodiscal lamina attached to?

Answer 4

The extreme posterior region of the articular disc

Question 5

The [superior/inferior] part of the retrodiscal lamina contains collagen rich fibers while the [superior/inferior] part contains elastin rich fibers.

Answer 5

inferior; superior

Question 6

The intermediate region of the articular disc is ______ inferiorly and ______ superiorly.

Answer 6

Concave; flat

Question 7

The anterior region of the articular dis is ______ inferiorly and _______ superiorly

Answer 7

Flat; concave

Question 8

True or False:

In a healthy TMJ the articulating disc stays in the same place when the jaw opens.

Answer 8

False; the disc slides with the translating condyle

Question 9

What is protrusion an important component of? retrusion?

Answer 9

Opening the mouth maximally; closing the widely opened and protruded mouth

Question 10

Technical name for overbite; technical name for underbite

Answer 10

Retronagthic jaw; prognathic jaw

Question 11

Movement that occurs and a side to side motion

Answer 11

Lateral excursion

Question 12

If you have lateral excursion to the left, then on the right side [protrusion/retrusion] occurs, and [protrusion/retrusion] occurs on the left side.

Answer 12

protrusion; retrusion

Question 13

To have typical mastication, the jaw must open_____. How much can the average adult mouth open?

Answer 13

Two knuckles worth (18mm); three knuckles (50 mm)

Question 14

How do the disc and mandibular condyle move during general translational movement? during protrusion? during retrusion?

Answer 14

They slide together; anteriorly together and follow the downward slope of the articular eminence; posteriorly together and follow the upward slope of the articular eminance

Question 15

How does the mandible move during protrusion and retrusion?

Answer 15

anteriorly and slightly downward; posteriorly and slightly upward

Question 16

What occurs during the early phase of depression?

Answer 16

Primarily rotation; condyle rolls posteriorly within the concave inferior surface of the disc

Question 17

What ligament is stretched during the early phase of depression?

Answer 17

Oblique portion of the lateral ligament; check reign ligament - once it is taut, second phase begins

Question 18

Primary ligament reinforcing the TMJ; stabilizes lateral side of capsule; typically described as a combo of horizontal and oblique fibers

Answer 18

Lateral (TM) ligament

Question 19

What occurs during the late phase of depression?

Answer 19

Primarily translation; condyle and disc slide together forward and inferior

Question 20

Where is the axis of rotation in the early phase of depression? during the late phase?

Answer 20

Migrates within the vicinity of the condyles; shifts inferiorly, usually below the neck of the mandible

Question 21

Where is tension increased during the late phase of depression?

Answer 21

The elastic superiorly retrodiscal lamina

Question 22

What does tension in the superior retrodiscal lamina initiate?

Answer 22

the early translational phase of closing the jaw

Question 23

What happens during bilateral contraction of the masseter muscle? unilateral contraction?

Answer 23

Elevation and protrusion; ipsilateral deviation

Question 24

What happens during bilateral contraction of the temporal muscle? unilateral contraction?

Answer 24

elevation and retrusion; ipsilateral deviation (but overall work is to bring it back to neutral

Question 25

What happens during bilateral contraction of the medial pterygoid muscle? unilateral contraction?

Answer 25

Elevation and protrusion; contralateral deviation

Question 26

What happens during bilateral contraction of the lateral pterygoid muscle? unilateral contraction?

Answer 26

Strong protrusion (inferior head is the primary depressor of the mandible while superior head helps control the position of the disc and joint during elevation); contralateral deviation

Question 27

What muscles force-couple to create rotation of the mandible around its axis of rotation to create a CONTROLLED movement to open the mouth?

Answer 27

Lateral pterygoid and the supra hyoid group of muscles

Question 28

True or false: | The superiorly head of the lateral pterygoid is active eccentrically while closing the mouth.

Answer 28

True

Question 29

What are symptoms of TMDs?

Answer 29

1. Muscle or joint pain during movement 2. Joint sounds "popping" 3. Reduced molar bite forces 4. Limited range in mouth opening 5. Headaches 6. Joint locking 7. Referred pain to the face and scalp

Question 30

What are causes of TMDs?

Answer 30

1. Stress 2. Oral habits 3. Asymmetric muscle activity 4. Sleep bruxism (grinding of teeth at night) 5. Chronic forward head posture 6. Abnormal anatomy 7. Trauma 8. Retrognathic or prognathic jaw

Question 31

What does spheno-basilar flexion lead to?

Answer 31

Widening medial to lateral, shortening of AP; creates a wide pallet (widening of the "freeway space")

Question 32

What does spheno-basilar extension lead to?

Answer 32

Elongating AP and raising the roof of the mouth; tall and narrow pallet (raising of "freeway space")

Question 33

What is freeway space important for?

Answer 33

Mastication and phonation