TMJ
“Craniomandibular Joint”: or synovial lined joint
TMJMandibular fossa of temporal bone with condyle of mandible Incongruent surfaces Two joint cavities with articular disc interposed Lower cavity = hinge joint Upper joint = gliding
TMJ
TMJ
Mandible
MandibleTMJ
CapsuleSurrounds the jointEncloses the discAttaches above the margins of the mandibular fossaTo the neck of the mandibleInner aspect of capsule attaches to discAbove disc – capsule looseBelow disc - taut
TMJ Capsule
TMJ CapsuleTMJ
Ligaments Lateral ligament - From zygomatic bone to run inferiorly and posteriorly to blend with the joint capsule to attach to lateral and posterior parts of the neck of the mandible Sphenomandibular Strong thin flat band lying on medial aspect of the joint Passes inferiorly and forwards from the spine of the sphenoid to the lingula Stylomandibular Extends from the apex of the styloid process to the lower part of the posterior border of the ramus of the mandible, near the angle
TMJ Capsule
TMJInnervated by CN V, Mandibular branchMovementsElevation, depression, retraction, protraction, side to sideElevation and depression involves the hinge like rotation of the condyle against the disc in the lower compartmentProtraction and retraction – actions whereby the condyle and disc move as one unit against the mandibular fossa. In protraction the condyle and disc glide forwards so that the condyle rides on the articular eminence – retraction = opposite
CN V Trigeminal
TMJ Motions
TMJ MotionsTMJ
Side to side – grinding movementsMandible is alternately protracted and retracted with the two sides moving in opposite directions so that one side is protracted while the other is retractedActions combined with elevation and depression, rhythmically and alternately
Muscles of Mastication
Masseter Temporalis Lateral pterygoid Medial pterygoid All innervated by CNV Opening of jaw (depression) primarily passive or gravity assistMasseter
TemporalisPterygoids
Pterygoids
A. Temporal BoneCranial component Mandibular fossa Articular eminence Articular surface from superior fossa to the anterior aspect of the eminence, thickest bone.