Transcript
Menatalla M. Elhindawy
Temporomandibular JointTMJ
Classification of joints
Fibrous joints
Cartilaginous joints
Synovial Joints
Classification of joints
SUTURAL Limited or no movement. The articulating surfaces
are covered with osteogenic layer to allow for bone formation.
GOMPHOSIS The movement is only
restricted to intrusion and recovery.
SYNDEMOSIS Intraostious ligament joins
between 2 bones: Radius and Ulna; Tibia and Fibula.
This ligament allows limited movement.
Fibrous Joint
Classification of joints
Limited or no movement
cartilaginous Joint
Classification of joints Allow significant movement. Articular surfaces covered with
hyaline cartilage. Capsulated joint. The capsule forms a cavity;
filled by synovial fluid formed by synovial membrane.
The joint cavity may be divided by an articular disk.
Classified according to number of articulating surfaces or shape of articulating surfaces.
Synovial Joint
Temporomandibular JointTMJ
Development of TMJ
Development of TMJ At 12th WIUL, 2
distinct mesenchymal condensations appear
condylar then temporal blastemata.
Both are apart Condylar blastema grows rapidly and
close the gap
Ossification of temporal blastema
while condylar remains mesenchyme
A cleft is formed above the condylar blastema forming
inferior joint cavity
A 2nd cleft is formed in relation to temporal
blastema after differentiation of
condylar into cartilage
Development of TMJ
Primitive disk is formed
Developing head of lat. Ptegoid ms is attached ot the
ant part of the disk
The disk is attached to the mallous of the
middle ear
Once ptregotympanic fissure is formed this connection is
lost
Early muscle contraction is
important for joint cavitation
Development of TMJ
TMJ
Articulating surfaces
Condylar head
Temporal bone
Articular disk
Capsular ligament
Joint cavity
TMJ.. Articulating surfacesA. Temporal bone
• Articular eminence and glenoid fossa.
• Present on the under surface of the squamous part of the temporal bone.
TMJ.. Articulating surfacesA. Temporal bone A. Fibrous covering “Fibrocartilage”
Un- even thickness.Thin at the glenoid fossa.
Thick at the eminence. Its outer layer fibers run parallel
to the surface and are densely arranged; while in deeper layers it is perpendicular to the surface.
TMJ.. Articulating surfacesA. Temporal bone B. Bone
The glenoid fossa is formed of a thin layer of compact bone.
The articular eminence is formed of thin layer of compact bone covering cancellous bone.
C. Cells No continuous cell layer on the
free surface of the fibrocartilage. Fibroblasts are flattened. Chondrocytes are isolated or in
small groups.
TMJ.. Articulating surfacesB. condylar head
Forms the articulation from below
TMJ.. Articulating surfacesB. condylar head A. Fibrous covering “Fibrocartilage”
Even thickness; composed of: I. Superficial layer… strong bundles
collagen type I fibers, some elastic fibers and fibroblasts inbetween bundles. “chondrocytes may present and may increase with age”
II. Deep layer “reserve cell zone”… rich in UDMCs present as long as hyaline cartilage is present.
By EM.. A layer called lamina splendens is found above the fibrous layer; 1-2 u with smooth outer surface and irregular inner one.
TMJ.. Articulating surfacesB. condylar head B. Bone
thin layer of compact bone covering the cancellous bone.
Cancellous bone trabeculae arranged in a radiating manner to reach the surface at a right angle give maximum strength.
Large marrow spaces decreased with age to increase the thickness of trabeculae.
Red marrow turns to yellow with age.
TMJ.. Articulating surfacesB. condylar head
Cartilagenous plateA layer of hyaline
cartilage is found underneath the fibrous covering.
This layer acts as a growth center until the age of 20.
Ossification takes place in the deep layer of the fibrocartilage.
Remnants of the cartilage may be found in old age.
TMJ.. Articulating surfacesB. condylar head
It is not arranged in parallel rows of cells at the interface between the forming bone and cartilage, therefor it is referred to as a 2ry cartilage.
Its growth aids in the downward and forward growth of the mandible.
TMJ
Articulating surfaces
Condylar head
Temporal bone
Articular disk
Capsular ligament
Joint cavity
TMJ.. Articular diskOval plate.Upper surface is concavo
convex.Lower surface is concave.Divide the joint cavity into:
upper large compartment.lower small compartment.
Medial and lateral blend with the joint capsule;
both blend with medial and lateral poles of the condyle.
so the disk and the condyle move as single unit.
TMJ.. Articular diskAnteriorly
Superior lamella: attached to anterior edge of articular eminence
Inferior Lamella: attached to the anterior surface of the condylar head.
Between the Superior and inferior lamella of superior head of lateral ptrygoid muscles are inserted.
TMJ.. Articular diskPostierioly
Superior lamella: attached to the posterior wall of the glenoid fossa and squamotympanic fissure.
Inferior lamella: attached to the posterior wall of the neck of the condyle.
TMJ.. Articular disk Fibers
Collagen type I arranged loosely and randomly EXCEPT in central portion they are arranged more tightly and organized.
Few elastic fibers. Fibroblasts are elongated and send
flat cytoplasmic processes between adjacent bundles.
Chondrocytes appear with advanced age and they increase the resentence and resilience of the fibrous tissue.
TMJ.. Articular disk The disk is well vascularized
and innervated at its periphery BUT not in its central portion
The disk is connected at its posterior margin to the capsule by the retrodiskal pad of loose connective tissue which is well vascularized and innervated.
TMJ
Articulating surfaces
Condylar head
Temporal bone
Articular disk
Capsular ligament
Joint cavity
TMJ.. Capsular ligament Fibrous, non elastic membrane.Unites and convers bones of the
joint.Attachments
Anterior: articular eminence. Posterior: squamotympanic fissure. Superior: margins of the glenoid
fossa. Inferior: neck of the condyle.
Above the disk it is lax; below the disk it is tightly attached to the condyle.
The posterior part of the capsule is thickened to for the tempromandibular ligament.
TMJ.. Capsular ligament Surfaces
anterior surface is faint. Inner surface is smooth and
glistering because of the presence of the synovial membrane lining which doesn't extend on the articular surface of the disk, articular eminence or condyle.
TMJ.. Capsular ligament The TMJ ligament restricts the displacement of
the mandible in 3 different planes: It prevents medial dislocation of one
joint by preventing lateral dislocation of the other.
Its oblique component limits the amount of inferior displacement.
Its horizontal component limits or prevents the posterior displacement.
Sphenomandibular ligament: represents the residues of Meckle's cartilage.
Stylomandibular ligament: runs from spine of the sphenoid to the angle of the mandible.
TMJ.. Capsular ligament The capsule consists of:
outer fibrous layer.Inner synovial layer
(synovial membrane) It is a thin layer of connective tissue which is rich in blood supply.
It lines the entire capsule with folds and villi of membrane protruding into the joint cavity.
TMJ
Articulating surfaces
Condylar head
Temporal bone
Articular disk
Capsular ligament
Joint cavity
TMJ.. Joint cavity
Consists of the synovial membrane which produce the synovial fluid.
Lines the entire capsule with folds or villi that protrude in the joint cavity.
These folds increase in number in cases of old age and pathologic conditions.
The synovial membrane doesn’t cover the articular surfaces or disk EXCEPT its posterior bilaminar region.
TMJ.. Joint cavity
Internal cells which don't form a contentious layer.
Consists of 2 layers: vascular subintema. cellular intema.
TMJ.. Joint cavity subintema
loose C.T containing vascular elements with scattered fibroblasts, macrophages, mast cells and fat cells.
Few elastic fibers. intema
1-4 layers of cells embedded in amorphous fiber free intercellular matrix.
3 types of cells I. A cells :they are mAcrophage like cellsII. B cells: they are fiBroblast like cells. III. Non A non B cells: they have cellular
morphology between A and B cells.
TMJ.. Joint cavityFunction of the synovial membraneI. Production of the synovial fluid. II. varying cell types such as monocytes,
Lymphocytes, free cynovial cells, polymorphnuclear leukocytes and macrophages.
III. Removal of foreign material.Function of the synovial fluid:
viscous fluid composed of Plasma with some added proteins and mucin.
IV. Nutrition to the disk and articular surfaces.V. Liquid environment for joint surfaces.VI. Lubrication to increase the efficiency and
decrease the erosion.
TMJ
Articulating surfaces
Condylar head
Temporal bone
Articular disk
Capsular ligament
Joint cavity
TMJ.. Blood supply
Arterial supplyDeep auricular and superficial temporal branches of the maxillary artery.Venous drainagePtregoid plexus of veins
TMJ.. Nerve supply Sensory supply Auriculotemporal and masseteric branches of
mandibular branch of the trigeminal nerve.Proprioception
I. Ruffini’s endings static and dynamic mechanoreceptors.
II. Pancinian corpuscles dynamic mechanoreceptors.
III. Golgi tendon organs static mechanoreceptors.
IV. Free nerve endings pain receptors.Motor function is derived from joint muscles.
TMJ.. Clinical considerations I. AnkylosisIt is mostly bony union rarely fibrous of the condylar head to the glenoid fossa. It is mainly caused by trauma or infection. It results in disability of the patient to open his mouth. II. Dislocation It is displacement of the condylar head from its position in the glenoid fossa. It is mostly anterior displacement (rarely posterior) caused by wide mouth opening (during yawing), small or short flat articular eminence and weak capsular ligament. It may be uni-lateral or bi-lateral.III. Popping and clicking noisesThe joint has palpable irregularities and produces these noises. However, use of a stethoscope reveals that about 65%of TMJs produce some kind of sound. This feature may not require treatment.
Thank you..
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