TMJ Flashcards
TMD incidence
- 50-70% of population experiences U/L TMD at least on 1 occasion
- 33% of population report continuing symptoms
- 5% of population pursue medical care
- Women>men
what is TMD assoicated with
- jaw grinding or clenching (bruxing)
- TMD is multifactorial: realted to physical, functional and psychological disorders
- no gold standard to detect TMD
TMD exam clinical findings
- joint sounds
- limitations of jaw movements
- hypermobility
- pain: joint, capsule/ligaments, disc dysfunction, muscle overuse
TMD classifications
- inflammatory disorders: OA, RA (hyper/hypomobility)
- disc disorders: disc positional changes (derangement-reducing and nonreducing)
- muscle/myofascial pain: overuse
TMD diagnostics
- MRI: most accurate to identify disc disorder, OA, RA
- also X-ray, CT scans, MSK US
- DX tests have little value detecting myofascial pain
- arthroscopy used to detect and treat a disc derangement
Ligaments of the TMJ
- joint capsule
- lateral temporomandibular ligament: limits excessive opening
Arthrology of the joint
- posterior glenoid process: prevents condyle from going too far posterior
- articular eminence: prevents condyle from going too far anterior
two joint spaces
- superior joint space
- inferior joint space
TMJ Disc and attachments
- posterior bands: superior and inferior attach to disc, enclosed retro-discal fat pad
- lateral pterygoid superior head attaches to disc
- anterior capsule has attachment to anterior disc
TMJ movements in superior and inferior joint spaces
- 1st condyles rotate in inferior joint space
- 2nd disc/condyle complex translation in superior joint space
TMJ innervation
- mandibular branch of trigeminal nerve
- mandibule nerve = motor to muscles of mastication, sensory to temptoral region of ear, jaw/cheeck, teeth and tongue
- auriculotemporal n: branch of mandibular n recieves snesory innervation from TMJ capsule, TMJ ligaments, retro-discal fat pad
TMJ osteo/arthrokinematics: opening
- opening normal 35-55 mm
- suprahyoids with stabilization from infrahyoids
- phase 1: condyles rotate on disc in lower joint space
- phase two condyle/disc translates anterior in upper joint space
- posterior bands prevent disc from going too far anteriorly
TMJ
Osteo/arthrokinematics: closing
- temporalis, massester, medial pterygoid
- phase 1: condyles rotates in lower joint space
- phase 2: condyles/disc translates posterior in upper joint space
- upper head lateral pterygoid (tension) prevents disc from going too far posteriorly
TMJ osteo/arthrokinematics
protrusion/retrusion
protrusion
- medial and lateral pterygoid working B/L
- translates anterior in upper joint space (3mm)
retrusion
- temporalis B/L draws mandible backward with massester assisting
Lateral shifting of the TMJ
- 12 mm
- ipslateral condyle rotates = temporalis, massester
- contralateral condyle translates anterior = lateral and medial pterygoids
Explain how lateral shifting is affected with a right sided hypomobile
- L ipsilateral condyle spins
- L temporalis and massester cause rotation
- R contralateral condyle translates anterior
- med/lat pterygiod translates R mandible anterior
if R is hypomobile the right cant translate anterior to allow lateral shift to left
TMJ hypomobility
- opening < 35mm
- capsular tightness bilateral - immobilization, post jaw fracture, jaw wiring
- unilateral hypomobility: opening = deviation to hypomobile Side - gives C curve due to unable to translate forward on hypo side
TMJ Hypermobility
subluxation
factors that increase this risk
- stretched TMJ capsule, ligaments
- anterior articular eminence is flatter and smaller
- condyle translates too far anterior onto articular eminence
- if U/L hypermobility jaw deflexs to opposite side the relative tighter side
TMJ hypermobility
dislocation
- trauma to jaw
- condyle slides over disc, disc acts as block
- jaw cant close
- mouth is open and deflected toward contralateral side
- can be someone who is really hypermobile- EDS
TMJ pathology
synovitis/capsulitis
- inflammation and pain
- bruxing, grinding, gum chewing, overuse
TMJ pathology
Traumatic arthritis
- post trauma or injury
TMJ pathology
OA/RA
- condyle, glenoid fossa, disc
- OA = crepitis, radiographic degeneration changes, osteophyates
- RA: joint erosion, ligament/capsular laxity, hypermobility
TMJ pathology
disc derangement
- displacement
- anteriorly displaced disc
- click w/ opening and closing as condyle slides over disc
TMJ pathology
- synovitis/capsulitis
- traumatic arthritis
- OA/RA
- disc derangment
- MMD
Normal posture resting position of TMJ
in proper C/S posture:
- head and neck in good alignment
- TMJ is in proper resting position
- tongue in light contact with roof of mouth
- there is no occlusal contact between teeth called freeway space
- there is minimal muscle activity
- a resting tone in jaw opening and jaw closing muscles
what happens with the TMJ joint in forward head position
- jaw drops
- jaw recedes
- gravity applies tension
- changes the position of the condyle with the joint
MMD: masticatory muscle disorder
- TMJ and muscle pain due to
- bruxing/grinding teeth,
- muscles over worked
- increase muscle tone/spasm => compression of TMJ joint
- myofascial trigger points in temporalis and masseter
MMD
treatment
- correct posture - C/S retraction
- massage/STM
- appliance from bruxing/grinding