MSK III: TMJ

Question 1

MSK III: TMJ

In the adult the mouth can be opened an average of_____ as measured between the incisal edges of the upper and lower front teeth

Answer 1

50 mm

3 adult knuckles

Question 2

MSK III: TMJ

Functional movement (depression) for eating is about ___ mm or ____ knuckles

Answer 2

18 mm

one knuckle

Question 3

MSK III: TMJ

The early phase of depression of the mandible, constituting the first 35% to 50% of the range of motion, involves primarily ______ of the mandible relative to the cranium.

Answer 3

rotation

the condyle rolls posteriorly

Question 4

MSK III: TMJ

The late phase of opening the mouth consists of the final 50% to 65% of the total range of motion. This phase is marked by a gradual transition from primary rotation to primary ​

Answer 4

translation.

The transition can be readily appreciated by palpating the condyle of the mandible during the full opening of the mouth.

During the translation the condyle and disc slide together in a forward and inferior direction against the slope of the articular eminence

Question 7

MSK III: TMJ

The early phase of elevation of the mandible involves primarily ______ of the mandible relative to the cranium.

Answer 7

translation

in a posterior and superior direction

Question 8

MSK III: TMJ

The late phase of closing (elevation) the mouth is marked by a

Answer 8

rotation

condyle roll anteriorly

Question 9

MSK III: TMJ

protrusion normal ROM

Answer 9

3 mm

Question 10

MSK III: TMJ

Protrusion arthrokinematics

Answer 10

• Condyle and disc translate anteriorly without significant rotation
• Mandible slides slightly downward during protrusion and upward during retrusion
• Extremely important for full opening

Question 11

MSK III: TMJ

lateral excursion normal ROM

Answer 11

11 mm each way

Question 12

MSK III: TMJ

nerve supply to the TMJ

Answer 12

trigeminal nerve - CN V

Mandibular → proprioceptive fibers TMJ

Question 13

MSK III: TMJ

why can sub-occipital compression of C1-C4 nerves present as TMD symptoms in the head and face?

(TMD = temporomandibular disorder)

Answer 13

Because afferent pain fibers from C1-C4 have projections through the spinal nucleus of the trigeminal nerve as it coordinates sensation from the opthalamic, maxillary and mandibular portions.

(because there is a crossing between the trigeminal nerve and C1 to C4 cervical nerve roots)

Question 14

MSK III: TMJ

Categorizing TMJ Disorders:

(all have pain in and around the TMJ, altered mandibular mechanics/motions, +/- joint noises)

Answer 14

• Osteoarthritis: crepitus
• Capsulitis/ligaments: loss of motion all directions
• Internal Derangement:
  
  • Stage I: disc anterior, inconsistent click, mild or no pain
  • Stage II: disc anterior reciprocal click, painful
  • Stage III: reciprocal click, most painful stage
  • Stage IV: click rare, no longer relocates, stays anterior, pain rare
• Psychological

Question 15

MSK III: TMJ

resting position of the TMJ

Answer 15

with tongue resting on the palate and mouth slightly open

Question 16

MSK III: TMJ

Intraoral lateral pterygoid palpation

Answer 16

upper vestibule

Question 17

MSK III: TMJ

intraoral medial pterygoid palpation

Answer 17

bottom lingual aspect of the teeth

Question 18

TMJ

Is there a C-shaped or an S-shaped deviation to the movement?

Answer 18

• C-shaped: hypomobility on side of direction
• S-shaped: motor control problem