TMJ Part 2 Flashcards
Phase I
Rotation
Lower Compartment
Phase II
translation
Upper compartment
Phase II Opening
Translate anteriorly
Phase II Closing
translate posteriorly
opening combines movements
closing ____
reverses
Phase I opening
rotation of condyle in lower compartment
first 11-25 mm
Phase II Opening
anterior translation of disk/condyle together in upper compartment
Total excursion
40-50 mm
Closing or elevation occurs in reverse pattern as opening
Translate posteriorly
Roll anteriorly, glide posteriorly
At the end of this phase (I) the disc is more
Posteriorly rotated position in relation to condyle
Superior striatum becomes tight as the condyle and disc
Translate anterior
Disc is affected by its own self seating, disc is rotated further
Posteriorly on condyle
Mandibular Protrusion and Retrusion
Occur in the
upper compartment
Protrusion
mandible juts forward
6-9 mm
Retrusion
mandible pulls back
3 mm
Lateral deviation primary
Ipsilateral condyle spins in transverse plane
Contralateral condyle translates anteriorly
Lateral Deviation Secondary
Ipsilateral condyle spins In the frontal plane about an A-P axis
Contralateral condyle is Displaced inferiorly
Lateral deviation range is
8-11 mm
Issue with lateral deviation, PT should focus on side
contralateral to movement issue
Chewing and Grinding
Combo of all motions at the TMJ
Mandibular Depressors
Gravity
Suprahyoids (anterior/post digastric)
Inferior lateral pterygoid
Inferior lateral pterygoid
Forward translation/protrusion of mandibular condyle in phase II
Mandibular Elevators (Closing)
Temporalis
Masseter
Medial Pterygoid
Superior lateral pterygoid
masseter and medial Pterygoid create a
sling for the TMJ and work synergistically to close
Superior lateral pterygoid plays roles by Keeping disk
slightly forward during closing
- Right Lateral Deviators
Left Medial and Lateral Pterygoids
Right Posterior Temporalis
- Left Lateral Deviators
Right Medial/Lateral Pterygoids
Left Posterior Temporalis
Protruders
Bilateral inferior Pterygoids
assist by medial pterygoids
Retruders
Posterior Temporalis
Posterior Digastric
Deep masseter
Roles of Muscles while chewing
Maintain appropriate alignment between
Disc and mandibular condyle
- High bite resistance between molars (halls cough drop)
reduces pressure ipsilaterally
compress contralaterally
Strong concentric contraction moves disc
anteriorly
Low bit resistance between molars (grape)
Disc in relatively ideal position between
Condyles and articular eminence
Face and skull grow rapidly during
first 6 years
Dimensions of face, including the mandible
Grow more rapidly than those of skull
most pronounced in ramus
During growth and development, mandibular angle decreases from
140-110
Postural forces and actual function of the TMJs will affect development of the
Dentofacial structures
Cervical muscle weakness > subsequent forward head posture, creating
anterior open back
Lengthening of lower part of face and increased Mandibular angle
Lack of dental force equilibrium and alignment >
Change shape of maxilla and mandible and TMJ function
Forward head posture creates passive tension in selected
Suprahyoid and infrahyoid muscles, altering the Resting posture of mandible
Effects of Forward Head Posture on Hyoid Bone and its Attachments
Mandible is pulled
Posteriorly and inferiorly, changing the position of the Condyle within the TMJ
