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What is the disc attached to?
condyle only..no attachment between disc and temporal bone, when condyle moves so does disc
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When palpating the TMJ, how should the motions feel?
smooth and bilaterally symmetrical
any deviations should be noted
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What may a crepitation or clicking be caused by?
- damaged meniscus
- synovial swelling secondary to trauma
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How do you have your patient position their mouth to check if the tmj is dislocated?
open as wide as possible
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What motions does the tmj use to function?
hinge and glide
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The tmj hinges within what? glides forward to what?
- hinges within the mandibular (glenoid) fossa
- glides forward to the eminentia (Articular eminence)
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The tmj joint cavity divides into what 2 portions?
- upper portion for hinge motion
- lower portion for glide motion
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What can asymmetrical dentation or poor occlusion cause?
can overload jt and cause palpable clicking in the external auditory canal
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What is another name for grinding or clenching the teeth?
bruxism
can also overload the jt
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What 5 motions can the tmj perform?
- depression
- protrustion
- elevation
- retrusion
- lateral deviation
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What happens at 1/4 to 1/2 of the beginning of mouth opening?
- condyle rotates anteriorly on the disc
- hinge portion
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What happens at normal mouth opening?
- condyle and disc move as a unit anteriorly and inferiorly on the temporal eminence
- glide portion
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What is the normal amount of mouth opening?
40mm or 3 fingers (35-50)
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What mm. assist in mouth opening?
lateral (external) pterygoid (dual heads- one pulls meniscus forward, other opens the jt)
suprahyoid mm (attach to mandible and th hyoid bone)
gravity
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What mm. assist in mouth closing?
- temporalis
- masseter
- medial pterygoid
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If the tmj disc dislocates, which way does it dislocate?
anteriorly
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What is a click caused by?
a disc that is displaced anteriorly
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Abnormalities may result from what?
- pathology
- improper dentition
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If a pt cant move thru the full ROM, what might they do?
substitute an inefficient, asymmetrical motion for one that was efficient but has since become more restricted or painful
substitution may cause more pain
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What are some inflammatory conditions of tmj?
synovitis/capsulitis
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What are some osseous mobility conditions of the tmj?
hypermobility/dislocations
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What happens with disc displacement with reduction?
- disc pops back into place when mouth opens
- full ROM, may not have pain
- ligaments are stretched out
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What happens with acute and chronic disc displacement without reduction?
- doesnt go back into place
- no click
- painful
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What disorder of the tmj is going to cause limited motion and pain?
arthritic conditions
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What disorder of the tmj is going to cause loss of mobility?
ankylosed conditions
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Where are symptoms of tmj located?
preauricular area (infront of ear)
symptoms are reproduced, increased or decreased with functional and/or parafunctional activities
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What are parafunctional activities?
misuse of jaw (jawbreakers, opening beer bottles with teeth)
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What are the compression/distraction forces of the tmj?
ex: biting a jawbreaker on right side will cause distraction of the tmj on right side and compression on the left side
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What do the symptoms of tmj disorders include?
- pain in preauricular area
- joint noises during mvmts of jaw
- limitation or difficulty in jaw motion
- pain may occur from m. spasm or myofasical pain in masseter, temporalis, or pterygoids (described as headache)
- tension in the mm. of cervical spine may itself be painful or cause reference pain (tension headache)
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What is the decreased vertical dimension of the bite or other dental problems?
malocclusion
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What are faulty jt mechanics?
from inflammation subluxation of the meniscus, dislocation of the condylar head, jt contractures, asymmetric forces from jaw and bite imbalances
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Where do m. spasms of the mastication mm. cause?
abnormal or asymmetric jt forces
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How do postural dysfunctions affect the tmj?
with forward head posture there is a retraction of the mandible and resulting stretch of the anterior and throat mm.
- increased activity in the mm. that close the jaw to counter the changed forces
- mm. and soft tissue in the subocciptal region become tight and nerves and jts become compressed and irritated
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What type of trauma affect the tmj?
- whiplash
- direct blow
- prolonged dental surgery with mouth opened for lengthy periods of time
- excessive stretches such as biting or chewing on lg pieces of hard food
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How do you determine AROM?
open and close mouth- 3 fingers or 35-40mm
protrude far enough that bottom teeth are infront of top teeth
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What is the primary mouth opener for MMT, and how do you test this m.?
lateral pterygoid
apply resistance as pt is trying to open their mouth
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What are the primary mouth closers for MMT, and how do you test these mm.?
masseter, temporalis
trying to force open the closed mouth with the palm of your hand
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What should you do to decrease tmj pain?
modalities, massage, relaxation techniques, soft foods
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What is the normal range for lateral deviation?
8-12mm
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What is the normal range for protrusion?
3-10mm
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