TMJ Flashcards
Lower portion of joint capsuleattaches ________________ to _______
mandibular condyle to disc
Upper portion joint capsule attaches ______ to _____________
disc to temporal bone
Where is the joint capsule thin and thick?
- thin posteriorly and anteriorly
- thickened/supported laterally/medially by collateral ligaments
What is the thickest and thinnest part of the disc?
- anterior is thickets
- thinnest in middle
What is the disc attached to? (3 total, anterior and posterior)
- joint capsule
- posterior - retrodiscal lamina
- anterior - lateral pterygoid and anterior articular capsule
action of lateral pterygoid
Pulls disc forward (concentrically) during opening and gradually pulls it (eccentrically) during closure
What is the function of the disc?
Separates joint cavity into two functional components
- Upper joint is a plane gliding joint for translation of mandible condyles
- Lower joint is a hinge joint that permits rotation of condyles
What is the retrodiscal lamina? Function?
Fatty layer that is innervated well to help with proprioception
- stabilize disc
prevents excessive translation of the disc over the condyle
What counters the lateral pterygoid pull?
tempromandibular ligament
- helps prevent posterior dislocation of the joint
- prevents medial slippage of disc
What are the muscles of mastication?
- temporalis
- masseter
- medial pterygoid
- lateral pterygoid
What are the suprahyoid muscles?
- stylohyoid
- digastric
- geniohyoid
- mylohyoid
What are the infrahyoid muscles?
- thyrohyoid
- sternothyroid
- sternohyoid
- omohyoid
action of the temporalis
elevate mandible
action of the masseter
elevation and protrusion of mandible
action of the medial pterygoid
elevate and protrude mandible
action of the lateral pterygoid
- protude and depress mandible
- lateral deviation of mandible (unilaterally)
What muscles depress the hyoid? What are their innervations?
infrahyoid muscles
- innervated by branches of C1-C3
What muscles elevate the hyoid?
suprahyoid muscles
action of the diagastric
depresses mandible against resistance and elevates hyoid
opening ROM
35-50 mm
- 3 fingers
lateral deviation ROM
10-15 mm
protrusion ROM
3-6 mm
retrusion ROM
3-4 mm
resting and closed packed position of TMJ
resting - slight opening (tongue resting on roof of mouth)
closed-packed - fully closed
MOI of masticatory muscle disorders
- strain/direct trauma
- overuse injury (grinding, nail binding, etc)
- central mediated pain
physical exam findings of masticatory muscle disorders
- tenderness and increased turger of muscles
- limited ROM - painful at end range
- pain with resistance testing
- pain w/ tongue depressor biting on ipsilateral side
general physical exam findings of joint dysfunction
- perauricular (ear) pain commonly primary complaint
- painful palpation of joint line
- pain w/ compressive load joint testing
disc dysfunction with reduction physical exam findings
- audible clincking and/or palpable clicking
- ROM intact
disc dysfunction without reduction physical exam findings
- report catching sensation with opening/closing
- limitations in opening ROM
pathomechains of c-type curve
- anteior displacement of a disc (ipsilaterally) w/o reduction OR unilateral muscle hypomobility
- hypomobility of ipsilateral joint
pathomechains of s-type curve
- muscular imbalance or medial displacement
- condyle “walks around the disc”
Biomechanics of early and late deviation
early - spasm
late - capsulitis/tight capsule
What is happening when there is a click during opening?
reduction of the disc as the mandibular condyle passes over the posterior border
What is happening when there is a reciprocal click during opening and closing?
Condyle slips posteriorly over (anteriorly) displaced disc
- clicking occurs with closing
T/F: DDWOR do not see a ROM limitation
false - usually see a potential ROM limitation
What curve is expected with DDWOR?
C curve
What may be the issue if the patient reports crepitus?
joint dysfunctions
