TMJ Anatomy

Question 1

Components of TMJ

Answer 1

• Temporal bone
• Mandible
• Articular Disc
• 2 distinct synovial chambers (upper/lower)

Question 2

Upper Synovial Chamber

Answer 2

-of the articular disc and glenoid fossa

Question 3

Lower Synovial Chamber

Answer 3

-of the articular disc and mandibular condyle

Question 4

Glenoid Fossa

Answer 4

-fossa in temporal bone where mandibular condyle rests

Question 5

Parts of Temporal Bone

Answer 5

(Posterior to anterior)

• posterior glenoid spine,
• glenoid fossa
• articular eminence
• articular tubercle

Question 6

Articular Eminence

Answer 6

• load bearing region for the mandible on the temporal bone

- convex

Question 7

Articular Tubercle

Answer 7

• most anterior aspect of temporal bone of joint

- does not provide a bony stop to translation of mandibular condyle

Question 8

Mandibular Condyles

Answer 8

-typically oriented with medial pole of condyle more posterior to lateral aspect and projects medially 15-20mm from ramus

Question 9

Ramus

Answer 9

• Vertical component of mandible
• has 2 projections (coronoid process and mandibular condyle)
• Sandwiched by Mm (Masseter and medial pterygoid)

Question 10

Coronoid process

Answer 10

• Anterior projection of ramus

- Attachment sight for temporalis and masseter Mm

Question 11

Articular Disc

Answer 11

• Biconcave
• Improve congruency between 2 convex surfaces
• Vascularized and innervated at each end (not in middle)
• Central segment load bearing portion

Question 12

Articular Disc Attachments

Answer 12

Restrict posterior migration of disc:

• Condyles
• Joint capsule (anteriorly)
• Superior/middle heads of lateral pterygoid

Restrict Anterior migration:
-Bilaminar Retrodiscal Pad (superior band: returns disc to neutral; Inferior band: checks anterior translation of disc)

Question 13

Mandibular Movements

Answer 13

• Depression
• Elevation
• Lateral deviation
• Protrusion
• Retrusion

Question 14

Normal Depression ROM

Answer 14

40-50mm

Question 15

Normal Lateral Deviation ROM

Answer 15

8-10mm

Question 16

Normal Protrusion ROM

Answer 16

5-6mm (on slides)

6-9mm (on notes doc)

Question 17

Normal Retrusion ROM

Answer 17

2-3mm

no more than 3mm

Question 18

1st Phase of depression

Answer 18

• Condules rotate anteriorly under the disc

- Mandible depresses 11-25mm

Question 19

2nd Phase of depression

Answer 19

• condyle/disc complex translates anteriorly and inferiorly on articular eminence
• accounts for remainder of opening to 40-50mm

Question 20

Lateral deviation Mechanics

Answer 20

(to right)

• Right condyle rotates R on vertical axis
• Left condyle translates anteroinferiorly on articular eminence

Question 21

Protrusion Mechanics

Answer 21

• Forward translation of condyles
• no rotation
• only in upper joint of TMJ

Question 22

Retrusion Mechanics

Answer 22

-Limited by soft tissue approximation of retrodiscal pad between condyle and posterior glenoid spine as well as TM ligament

Question 23

Chewing

Answer 23

complex combo of elevation, lateral deviation, and protrusion of mandible

Question 24

Muscles of TMJ

Answer 24

• Temporalis
• Masseter
• Medial Pterygoid
• Lateral Pterygoid
• Suprahyoids
• Infrahyoids

Question 25

9 Points of Hypermobility test

Answer 25

``` 1/2: pinky extends >90* 3/4: Thumb to forearm 5/6: hyperextension of elbows >10* 7/8: hyperextension of knees 9: palms flat on floor with knees straight ```

Question 26

Muscles of Elevation

Answer 26

- Masseter - Temporalis - Pterygoids

Question 27

Muscles of Protrusion

Answer 27

- Masseters | - Pterygoids

Question 28

Muscles of Depression

Answer 28

- Eccentric contraction of elevation muscles - Depression against resistance: digastric muscle (concentric) - Other depressors: lat pterygoid and gravity)

Question 29

Muscles of Retrusion

Answer 29

Temporalis

Question 30

Ligaments

Answer 30

- Temporomandibular Ligament - Stylomandibular Ligament - Sphenomandibular Ligament

Question 31

Temporomandibular Ligament

Answer 31

- Attach from articular eminence to neck of condyle - Limits lateral, inferior & posterior movement of mandible - Suspends mandible against gravity

Question 32

Stylomandibular Ligament

Answer 32

- Styloid process to mandibular angle | - appear to be suspensory ligaments

Question 33

Sphenomandibular Ligament

Answer 33

- Sphenoid to mandibular angle | - appear to be suspensatory ligaments

Question 34

Inferior Joint capsule

Answer 34

- joins the disc to the nect of the condyle | - tighter than superior capsule

Question 35

Superior Joint capsule

Answer 35

- Loosely joins the disc to the temporal bone | - Allows for translation of disc on articular eminence

Question 36

CN V

Answer 36

- Trigeminal N - Mm of mastication - Sensory to face, scalp, teeth, oral cavity

Question 37

Auriculotemporal Nerve

Answer 37

- branch of CN V | - innervation of TMJ and some ear symptoms associated with TMJ

Question 38

CN VII

Answer 38

- Facial N - Mm of facial expression - Digastric Mm

Question 39

Unilateral Action of Pterygoids

Answer 39

Deviate to opposite side

Question 40

Unilateral Action of Temporalis

Answer 40

Deviate to same side

Question 41

Active Control of Disc

Answer 41

- Lat pterygoid oriented anteromedially in relationship to condyle and attaches to anterior disc - Ptery silent in opening but active in closing - thought to control eccentric return of disc to neutral position