TMJ Flashcards
describe mandible growth
different parts grow in congruence with each other but in general tends to happen in anterior posterior direction as well as in a flaring direction
what does an overdeveloped ramus/body do to the jaw
flat angle of jaw
what does an underdeveloped ramus/body do to the jaw
steeper incline/angle of the jaw which can lead to crowding
what are the TMJ innervation receptors and what do they each do
-ruffini corpuscles: proprioception
-pacinian corpuscle: dynamic mechnoreception (chewing)
- golgi tendon organs: static mechanoreceptors (rest)
- free nerve endings: detect pain
what is the joint classification of the TMJ
synovial sliding ginglymoid joint
what does a synovial joint do
permits movement between 2 bones
what does the sliding joint classification of the TMJ describe
the second part of jaw opening, sliding anterior of the condyle over the glenoid fossa
what does the ginglymoid joint classification of the TMJ describe
the first part of opening, hinge portion
what is the joint cavity filled with
synovial fluid that is derived from villus cells which line the internal space of the capsule
what does the fibrous disc do
separates the bones preventing damage
how do the condylar neck and head develop
endochondral ossification
what is multidirectional growth capacity
unlike long bones of the body the cartilage cells in the condylar head and neck do not exhibit ordered columns
what does the fibrous capsule encapsulate
the entire joint
what does the superior lateral pterygoid attach to
joint capsule and articular disc
what does the inferior lateral pterygoid attach to
condylar neck in pterygoid fossa
what is the glenoid fossa
bony part of the temporal bone that allows for articular surface of mandibular condyle to fit in
describe the collagen fibers in the glenoid fossa
arranged in multiple directions allowing for a more robust surface of articulation
what are the inner perpendicular collagen fibers on the posterior slope of the TMJs articular eminence responsible for
resisting compression of the mandibular condyle against the articular surface of bone
how do the articulating surfaces of the TMJ change with age
covered with a layer of fibrous tissue, with increasing age the deeper portions of the fibrous covering may exhibit islands of cartilage
how do the condylar heads of the TMJ change with age
the condylar head becomes less cellular
how does the articular disc of the TMJ change with age
becomes more cellular
what is the retrodiscal connective tissue made of
comprised of collagen and elastic fibrous connective tissue, fat cells, and is highly vascular
what does the composition of the retrodiscal connective tissue allow for
mandible to move freely in an anterior motion
is there articulation between the retrodiscal connective tissue and the condyle
no
what do the elastic fibers of the retrodiscal connective tissue insert into posteriorly
petrotympanic fissure
what do the elastic fibers of the retrodiscal connective tissue insert into anteriorly
superior head of the lateral pterygoid
describe anterior dislocation of the disc
the disc is attached to the medial and lateral surfaces of the condyle but not the temporal bone. when the mandible moves the disc moves as well. movement of the disc back and forth can cause asymptomatic clicking sound present in 70% of population
where is all articulation of the disc
on the fibrous portion/dense area
what does the dense area of the disc restrict
the posterior movement of the mandible and maintains the condyle in the anterior part of the glenoid fossa
what is the function of the synovial membrane and where is it located
function: necessary for sliding movement
location: inner surface of the fibrous capsule
what are the 3 distinct layers of tissue in the TMJ synovial membrane
-the most peripheral/external layer is the fibrous capsule of the joint
- the intermediate layer is the vascular subintima
- the most internal layer is termed the intimal layer
what two cell types does the intimal layer contain and what do each do
-type A synovial cells: macrophage like cells that exhibit phagocytic functions and are capable of producing inflammatory cytokines such as interleukins or tumor necrosis factors
-type B synovial cells: fibroblast like cells that synthesize hyaluronate which is a major component of the synovial fluid in the superior and inferior compartments of the joint
what is hyaluronate
major part of slippery synovial fluid that allows for free movement of the joint
what happens in inflammatory joint disease in chronic or acute traumas
type A cells fuse and transform into a mulitnucleated giant cell and function like osteoclasts, resorbing bone and cartilage and elevate cytokine levels
if intense enough what can inflammatory joint disease reaction cause
resorption within spongiosa of head and neck with resorption occurring simultaneously on internal and external surfaces of the condyle
what is the arachidonic acid pathway
trauma -> activation of arachidonic pathway -> leukotrienes, thromboxanes and prostaglandins activate type A cells -> increased IL and TNF -> macrophage/osteoclastic activity -> tissue destruction
what is arthritic degeneration
flattened condylar head occurs due to osteoclastic activity causing an almost bone on bone contact due to lack of cartilage layer
what are found on condylarheads in arthritic degeneration
osteophytes
what is the result of the degeneration of tissue in arthritic degeneration
decreased vascularity found in the retrodiscal area leading to pain on function
what is internal derangement and what does it result in
disc is trapped in the antero medial position leading to limited opening, pain, and clicking upon opening
what is ankylosis
loss of articular coverings and synovial membranes lead to direct bone to bone fusion
what is ankylosis caused by
untreated fracture
what can anklyosis in the TMJ lead to
specific malocclusion issues
what is the result of the activation of leukotrienes, prostaglandins, and thromboxane’s activation of Type A cells
swelling, pain and vasoconstriction
