TMJ

Question 1

Prevalence

Answer 1

More common in women than man 2:1

Question 2

Disc Anatomy

Answer 2

Biconcave, highly innervated

Question 3

Muscles of mastication

Answer 3

Pterygoids (Medial and Lateral)
Masseter
Temporalis

Question 4

Lateral Pterygoid

Answer 4

Pulls medially and depresses/protrudes the mandible

Question 5

Lateral Ligament

Answer 5

Reinforces the joint, sprain of this ligament will cause a medial disc migration (unopposed pull from the LP)

Question 6

Biomechanics of Opening

Answer 6

Translation (condyle is moved with the disc as disc is stretched)
Rotation (condyle rolls relative to the disc)

1st 50% of motion is posterior roll/rotation as mandible swings inferior/posterior

2nd 50% Transition from rotation to anterior/inferior translation

MAXIMUM OPENING REQUIRES THAT THE CONDYLE ROTATION > SWING. IF NOT ENOUGH ROTATION THEN POSTERIOR IMPINGEMENT WILL OCCUR.

Question 7

Opening Muscles

Answer 7

Lateral Pterygoid (inferior head)
Suprahyoid group

Question 8

ROM Norms

Answer 8

Adult (50 mm) or 3 PIP joints, lateral deviation is usually 1/4 of opening

Women (39-43 mm)
Men (41-44 mm)

*Most mastication requires 18mm or at least 2 PIP joints

Question 9

Closing Muscles (MMT)

Answer 9

Masseter
Medial Pterygoid
Temporalis

Question 10

Closing Mechanics

Answer 10

Reverse of opening

Posterior superior translation followed by anterior rotation

Question 11

Protrusion Muscles

Answer 11

Lateral Pterygoids
Medial Pterygoids
Masseter

*Important for maximal opening
Normal ROM (3-6 mm)

Question 12

Retraction Muscles

Answer 12

Temporalis
Suprahyoid group

*Important for maximal closing
Normal ROM (3-4 mm)

Question 13

Lateral Deviation

Answer 13

Ipsilateral (Masseter/Temporalis)

Contralateral (Pterygoids)

Question 14

Types of disc derangement

Answer 14

Ant. disc with reduction
Ant.Med. disc with reduction
Ant. disc without reduction or “Closed Lock”
Post. disk displacement or “Open Lock”

Question 15

Ant. disc with reduction

Answer 15

*Disc is pulled forward at rest (already subluxed)

“2 clicks”
1st is upon opening (reduction)
2nd is upon occlusion (subluxation back to resting position)

Question 16

Ant. disc displacement without reduction

Answer 16

Disc is stuck and doesn’t allow mouth to open “Locks” after first click.

*Disc may also progress to point where reduction no longer occurs and thus joint noise becomes absent

Question 17

Deviations with opening and closing

Answer 17

C and Reverse C - Hypomobile to side of convexity
*S and Reverse S - Muscle imbalance or medial disc displacement

Lateral Deviations - Early = Muscle Spasm, Late =Capsulitis or hypomobility

Limited/painful closing = capsulitis (unable to fully translate back to resting position)

Question 18

Tongue Thrust

Answer 18

Normal test Hyoid should move up/down quickly

Abnormal (+) Hyoid moves up only and coupled with suboccipital contraction

Question 19

Clinical Pearls

Answer 19

Pain with full opening is extra-articular
Pain with biting firm objects is intra-articular
OA is characterized by A.M. stiffness which improves

Question 20

Interventions

Answer 20

OMT and TE > Bite guards for pain/ROM
Rocabodo is used for NMR (not much evidence)

Arthroplasty dec. pain but don’t improve function

Question 21

TMJ pain-referral patterns

Answer 21

Medial Pterygoid (sideburns)
Lat. Pterygoid (disc and cheek)
Masseter (front face)
Temporalis (hard palate, temples and forehead)
Occipitofrontalis (eye and back of head)
Digastric (Lateral C/S)

Question 22

Assessment

Answer 22

Mobilization not performed if patient has false teeth
Special Tests (Mouth Breather, Tongue Thrust)

Question 23

What is Trismus

Answer 23

Masseter spasm which often occurs after dental procedure