TMJ Anatomy and Clinical Presentation

Question 1

the joint capsule of the TMJ is divided into ____ portions. Describe each

Answer 1

two portion

upper → attaches disc to temporal bone

lower → attaches mandibular condyle to disc

the joint capsule itself is thin A/P and thickened/supported M/L by collateral ligaments

Question 2

describe the structure and function of the disc at the TMJ

Answer 2

bi-concave and flexible

oval fibrocartilage plate

made up of A/P and intermediate bands

function is to separate joint cavity into 2 functional components and disperse force

Question 3

where is the disc located in the TMJ?

Answer 3

positioned between the mandibular fossa of the temporal bone and condylar process of the mandible

Question 4

describe the attachments of the disc in the TMJ

Answer 4

posterior attachment → retrodiscal lamina

anterior attachment → lateral Pterygoid (pulls disc forward during mouth closure) and anterior articular capsule

Question 5

describe the structure of the retrodiscal lamina

Answer 5

ligament from temporal bone to the posterior border of the disc

made up of 2 layers divided by a loose connective tissue

has elastic fibers that aid in disc recoil during mouth closing

Question 6

what is the function of the retrodiscal laminae?

Answer 6

1. stabilize the disc
2. prevent excessive translation of the disc over the condyle

Question 7

describe the structure and function of the temporamandibular ligament

Answer 7

• Structure → fan shaped, thickening of anterior joint capsule from neck of mandible to zygomatic arc
• Function
  
  • helps prevent posterior dislocation of the joint
  • prevents medial slippage of disc
  • counters lateral pterygoidpull

Question 8

List the muscles of mastication

Answer 8

1. Temporalis
2. Masseter
3. M/L Pterygoid

Question 9

List the origin, insertion and action of the Temporalis

Answer 9

1. Origin → temporal fossa
2. Insertion → coronoid process on anterior ramus of mandible
3. Action → elevate mandible

Question 10

List the origin, insertion and action of the Masseter

Answer 10

1. Origin → inferior and medial zygomatic arch
2. Insertion → coronoid process of lateral ramus of mandible
3. Action → elevation and protrusion of mandible

Question 11

List the origin, insertion and action of the medial pterygoid

Answer 11

1. Origin
   
   • medial surface of lateral pterygoid plate
   • pyramidal process of palatine bone
   • tuberosity of maxilla
2. Insertion → medial aspect of mandibular ramus
3. Action → elevation and protrusion of mandible

Question 12

List the origin, insertion and action of the lateral pterygoid

Answer 12

1. Origin
   
   • superior head to lateral surface of greater wing of sphenoid
   • inferior head to lateral surface of lateral plate
2. Insertion → neck of mandible and articular disc as well as TMJ capsule
3. Action
   
   • protrude and depress mandible
   • lateral deviation of mandible (unilaterally)

Question 13

What innervates the infrahyoids and what is their gross action?

Answer 13

branches of C1-C3

depress hyoid

Question 14

what is the role of the Digastric?

Answer 14

depress mandible against resistance and elevates hyoid

Question 15

what innervates the muscles of mastication?

Answer 15

Mandibular nerve (V3 → branch of trigeminal)

Question 16

The Mandibular nerve provides sensory info for what areas?

Answer 16

1. Teeth
2. Temporal region
3. external auditory meatus
4. tympanic membrane
5. lower face and lip
6. mucosa anterior 2/3rds of the tongue
7. floor of oral cavity

Question 17

Desribe the arthrokinematics of the TMJ joints

Answer 17

1. 50% of motion occurs as rolling in the lower joint
   
   • condyle on temporal bone
   • disc remains stationary
2. 50% of motion occurs in upper joint as gliding
   
   • begins at mid-opening
   • disc pulled anteriomedially by lateral pterygoid
   • condyle along sigmoid-shaped temporal bone
   • disc slides along w/condyle

Question 18

List the osteokinematic motions and their normative values for the TMJ

Answer 18

1. Opening → 35-50 mm
2. Lateral deviation → 10-15 mm
3. Protrusion → 3-6 mm
4. Retrusion → 3-4 mm

Question 19

what is the resting (open pack) position for the TMJ?

Answer 19

slight opening (tongue resting on roof of mouth)

Question 20

how common is TMD?

Answer 20

65-85% of US population experience some TMD symptoms during their lives

more common in women (8-15%) than men (3-10%)

Question 21

Your differential list for someone who presents with TMJ issues includes what broad categories?

Answer 21

1. Musculoskeletal
   
   • Myofacial
   • Internal derangement
   • degenerative arthropathy
   • Intra-oral → refer to dentist
   • C-Spine referral
2. Neurogenic
   
   • Peripheral neuralgia (trigeminal normally)
3. Vascular
   
   • cardiac referral (angina, MI)
   • HA
4. Other

Question 22

TMD can be broken down into what 3 broad categories and subcategories?

Answer 22

1. Masticatory Muscle disorders
   
   • with normal opening
   • with limited opening
2. Disc displacements
   
   • with reduction
   • without reduction and with limited opening
   • without reduction and without limited opening
3. Joint Dysfunction
   
   • arthralgia
   • osteoarthritis
   • osteoarthrosis

Question 23

Masticatory Muscle Disorders can be caused by what?

Answer 23

1. Acute → strain
   
   • direct trauma (blow to the face, excessive widening with dental procedure, etc.)
2. Chronic → overuse injury
   
   • parafunctions
   • guarding
3. Centrally mediated pain

Question 24

define parafunctions

Answer 24

clenching, grinding teeth, nail biting, etc

behaviors relating the jaw movements that are not normal

Question 25

what can result from masticatory muscle disorders?

Answer 25

1. reduced motion and altering of occulsion 2. trigger points with pain referral to: * face * teeth * auricular area * temporal area * perioccular area * upper cervical area

Question 26

List some physical exam findings for an individual with masticatory muscle disorders

Answer 26

1. tenderness and increased turgor of muscles of mastication 2. aberrant motion pattern with AROM testing 3. Limited ROM when stretching involved structure * painful at end-range motion 4. pain w/resistance testing to invovled structure 5. pain w/tongue depressor biting on ipsilateral side

Question 27

describe the TMD category of joint dysfunction

Answer 27

invovles the disc, joint surfaces, capsule, ligaments retrodiscal tissue, and/or synovium Mechanisms involve micro/macrotrauma can lead to guarding

Question 28

List the general findings for Disc displacements and Joint Dysfunction

Answer 28

1. Perauricular pain commonly primary complaint 2. painful palpation of joint line 3. pain with tests that place compressive load on joint structures

Question 29

list clinical findings for DDWR

Answer 29

1. audible clicking and/or palpable clicking (1/3 trials) 2. joint motion typically intact

Question 30

list clinical findings for DDWOR

Answer 30

1. report of catching sensation with opening/closing 2. limitations in opening ROM

Question 31

describe the pathomechanics of an C-type curve

Answer 31

anterior displacement of disc (ipsilaterally) without reduction or unilateral muscle hypomobility hypomobility of ipsilateral joint

Question 32

describe the pathomechanics of an S-type curve

Answer 32

muscular imbalance or medial displacement condyle "walks around the disc"

Question 33

describe what is going on during DDWR

Answer 33

1. Clicking: * partial anterior displacement or dislocation of the disc in resting position * opening click indicating reduction of the disc as the mandibular condyle passes over the posterior border 2. Reciprocal clicking (clicking occurs with closing) * condyle slips posteriorly over (anteriorly) displaced disc

Question 34

describe what is occuring during DDWOR

Answer 34

the disc no longer reduces, but remains anteriorly reduced this can limit mouth opening result in compression loading on retrodiscal lamina

Question 35

Describe what occurs with Open Lock

Answer 35

the condyle moves over the anterior rim of the disc at max opening the disc lies posterior to the condyle outside of the fossa which prevents the condyle from sliding back masseter and temporalis guard

Question 36

Describe what occurs with closed lock

Answer 36

disc displacement w/o reduction partial anterior displacement or dislocation of the disc in resting position mandibular condyle unable to pass over the posterior border of the disc with opening (disc remains bunched anterior to the mandibular condyle)

Question 37

what is Joint dysfunction? What are the types that can occur at the TMJ?

Answer 37

inflammation of capsule, ligaments, retrodiscal tissue, synovium of the TMJ structural changes of joint surfaces, 3 types: Degenerative, Osteoarthritis, Osteoarthrosis

Question 38

Describe the clinical presentation for joint dysfunction of the TMJ

Answer 38

1. May report crepitus 2. unilateral vs bilateral 3. deviation with opening, protrusion, contralateral deviation (unilateral)