TMJ Flashcards
what bones form the TMJ
temporal (squamous portion) and mandible
- mandibular fossa
- articular eminence
- squamotympanic fissure – petrotympanic fissure
how can the articular eminence withstand forces of heavy loading?
made of dense bone
can the roof of the fossa withstand occlusal forces?
no; the bone is too thin
where is fibrocartilage found?
in the mandible and slope of articular eminence
zones of the articular surfaces
- fibrous articular covering
- proliferative layer
- hypertrophic zone
- calcified cartilage
- mixed bone spicules
what does the proliferative layer contain?
chondrocytes, fibroblasts, undifferentiated cells
apoptosis occurs at which zone?
end of the hypertrophic zone going into calcified cartilage
what lies between the 2 bones of the TMJ?
articular disc
articular disc
- attached to joint capsule 360 degrees around
- disc is an extension of the capsule
- made of dense fibrous connective tissue
three functional ligaments of the TMJ
- collateral (discal) ligaments
- capsular ligament
- temporomandibular (lateral) ligament (TML)
two accessory ligaments of TMJ
- sphenomandibular ligament
- stylomandibular ligament
collateral (discal) ligaments
- attach medial and lateral borders of the articular disc to the poles of the condyle
- responsible for dividing the joint into superior and inferior joint cavities
- vascular and innervated – info regarding position and movement
capsular ligament
- attached superiorly to temporal bone
- inferiorly, the fibers attach to neck of condyle
- function–encompass joint, thus retaining synovial fluid
- innervated and proprioceptive
the capsule is lined on its inner surface by—
synovial membrane
temporomandibular ligament
- 2 parts–outer oblique and inner horizontal
- inner horizontal–> limits posterior movement of condyle and disc
- oblique–> resists excessive dropping of the condyle, limiting the extent of mouth opening
most common fracture of mandible–
condyle
sphenomandibular ligament
does not have any significant limiting effect on mandibular movement
stylomandibular ligament
limits excessive protrusive movements of mandible
shape of articular disc
- biconcave shape
- thinnest in center
- thickest posteriorly and anteriorly
- attached to poles of mandible by M & L discal ligaments
- disc moves with mandible
retrodiscal laminae (bilaminar zone)
- superior lamina (attached to squamotympanic fissure)–> elastic fibers
- inferior lamina (attached to condylar neck)–> collagen fibers (more fibrous)
vasculature of TMJ
- arterial–superficial temporal and deep auricular artery
- target–retrodiscal tissue
- drainage via pterygoid venous plexus
innervation of TMJ
primarily–auriculotemporal (V3) nerve to retrodiscal tissue
secondary–by masseteric nerve anteriorly
*general sensory
*primarily to retrodiscal tissue
ruffini’s corpuscle
- posture (proprioception)–dynamic and static balance
- clusters in superficial layers of joint
- active in every position of joint
- signal static position, changes in intraarticular pressure; and direction, amplitude, and velocity of joint movements
pacini’s corpuscle
dynamic mechanoreception movement accelerator and deceleration low threshold deeper onion like
golgi tendon organ
- static mechanoreception
- protection (ligament)
- inactive in immobile joints
- active only when joint is at extremes of range of movement
- only in tendons
free nerve ending
- pain (nociception)
- protection (joint)
- no capsule
- terminal in a joint
- distributed widely
accessory muscles of mastication
suprahyoid and infrahyoid muscles
mechanism in TMJ disorders
neuro-immune-endocrine interaction
- inside retrodiscal tissue
- stress hormones–> sensory nerve–> substance P and CGRP disturb vasculature in TMJ–> accumulate until tissue destruction via elastase and MMP-9
