TMJ

Question 1

Osteo/Arthrokinematics

Answer 1

convex - mandibular condyles
concave - temporal fossa
disc interposed between joint partners

Question 2

LPP and CPP

Answer 2

LPP - mouth slightly open (functional rest position)

CPP - teeth clenched or full opening

Question 3

Motion

Answer 3

max/full opening - 40-60 mm
functional opening - 40 mm
ant rot of mandibular condyles - 25 mm
ant translation of condyles - 15 mm (translation begins when mouth has opened 10-15 mm)
lateral deviation - 1/4 opening (8-12 mm)
protrusion - about 3-6 mm

Question 4

Normal Sequencing of Opening/Closing of TMJ

rest, mid-open, functional, full, closure

Answer 4

rest position - LPP of TMJ, disc interposed between condyles and fossa (normally sits slightly ant)
mid-opening rot - ant rot of condyle on disc (now “relatively” post with respect to condyle)
functional opening - disc and condyle glide forward together for short distance
full/max opening - further ant translation
closure - condyle rot post, disc moves into more ant position relative to condyle

Question 5

TMJ Movement

Answer 5

rotation occurs in lower joint space between condyle and inferior surface of disc
translation occurs in upper joint space between superior surface of disc and temporal

Question 6

Pterygoids

Answer 6

lat - opens, medial - closes

when working together on one side, lat deviation to that side

Question 7

Infrahyoid

Answer 7

stabilize hyoid bone to allow action by other hyoid muscles

Question 8

Digastric

Answer 8

primarily mouth opener with lat pterygoid; requires hyoid bone to be stabilized

Question 9

Stylohyoid

Answer 9

initiates and assists opening of mouth

Question 10

Temporalis

Answer 10

mandibular closing and retraction

Question 11

Masseter

Answer 11

primary - mandibular closing

secondary - protrusion (superificial fibers), retraction (deep fibers)

Question 12

Common Symptoms

Answer 12

pain in TMJ area (esp with eating)
joint noise - clicking if disc dysfunction and/or hypermobility, grinding if arthritis of joint
trismus - restriced jaw movement resulting from formation and shrinkage of CTs in post mandibular or temporomandibular region (can result from trauma, infection, surgery, or radiation treatment)

Question 13

Functional Disc Displacement with Reduction

Answer 13

reciprocal clicking indicates an ant disc that reduces (first click) and dislocates again (second click)

Question 14

Disc dislocation without Reduction

Answer 14

disc displacement anteriorly which does not reduce as mouth opns
full opening restricted, jaw may lock

Question 15

Hypermobility Symptoms

Answer 15

joint often goes “out
pt can often self-reduce
may have more than normal functional opening

Question 16

Inflammatory Dysfunctions

Answer 16

OA jt - limited motion, palpable crepitus during active motion
capsulitis/synovitis

Question 17

Capsular Fibrosis

Answer 17

restricted capsule motion
maybe secondary to prior trauma, prolonged immobilization, or microtrauma leading to shortened capsuloligamentous structures