TMJ Flashcards
what kind of joint is the TMJ
synovial joint (divided into hinge and gliding)
what are the articulations of the TMJ
between head of mandible and mandibular fossa and articular tubercle on the squamous part of the temporal bone
why is the TMJ a modified synovial joint
includes a small disc
what does the small disc in the TMJ permit
gliding movements between the head of the mandible, mandibular fossa and articular tubercle
the TMJ is surrounded by
fibrous capsule
what is the nerve supply of the TMJ
auriculotemporal and masseteric
what covers the articular surfaces of the TMJ
fibrocartilage (membranous ossification)
what ligaments reinforce the TMJ
lateral temporomandibular ligament
sphenomandibular and stylomandibular ligaments (medially)
what muscle attaches to the articular disc and capsule of the TMJ
lateral pterygoid
what movements can take place between the head of the mandible and the mandibular fossa/disc
simple hinge movements
what happens at the TMJ to permit the mouth to open more fully
head of the mandible is pulled forwards towards the articular tubercle by lateral pterygoid
the close the mouth what action must occur
head of mandible is pulled backwards away from the articular tubercle by posterior fibres of temporalis
what muscle causes head of mandible to be pulled backwards away from the articular tubercle
posterior fibres of temporalis
what does the articular disc do to the TMJ
divides the cavity
increases the congruency of the articular surfaces allowing a bigger, smoother movement
the joint cavity of the TMJ is divided by
fibrous articular disc
where does depression and elevation occur at the TMJ
between head of mandible and disc (hinge)
where does protrusion and retraction occur at the TMJ
between disc and mandibular fossa and articular process (gliding)
what happens to close the mouth
elevation and retraction pull condyle backwards
what happens to open mouth
depression and protrusion to slide disc and condyle forwards towards tubercle
what occurs in chewing
asynchronous gliding
what occurs in elevation of the mandible
head of mandible and disc move backward and head rotates on lower surface of disc
what muscles cause elevation of the mandible
temporalis
masseter
medial pterygoid
what occurs in depression of the mandible
head of mandible rotates on undersurface of articular disc and mandible is pulled forward
what muscles cause depression of the mandible
lateral pterygoid
digastric
geniohyoid
mylohyoid
(gravity)
what happens in protrusion of the mandible
articular disc and head of mandible move forward
movement in upper part of cavity
what muscles cause protrusion of the mandible
lateral pterygoid and medial assists
what occurs in retrusion of the mandible
articular disc and head of mandible pulled backward into mandibular fossa
what muscles cause retrusion of the mandible
posterior fibres of temporalis
what occurs in lateral chewing
protrusion and retrusion combined
what muscles cause lateral chewing
pterygoids
what assists in depression of the mandible
gravity and suprahyoid muscles
what muscle does not move the mandible but aids in the process of eating
buccinator
how does buccinator aid in the process of eating
forms the lateral walls of the oral cavity and must be moved during chewing or you will accidentally bite the inside of cheek
