TEMPEROMANDIBULAR JOINT BY DR. VARDENDRA M

1. Temporomandibular
Joint
Dr. Vardendra M
Reader
Dept of Oral Pathology
NDC, Raichur

2. Classification of joints
• Fibrous
Suture
Gomphosis
• Cartilaginous
Primary
Secondary
• synovial

3.  Ginglymo diarthrodial joint.
 Synovial joint between head of the mandible and
mandibular fossa on the under surface of the
squamous part of the temporal bone.
 Separated into upper and lower cavities by
fibrocartilaginous disc within joint.

5. • Artculating surfaces, articular fibrous covering
• Articular capsule
• Articular disc
• Ligaments of TMJ

6. Articulating surfaces

7. Histology of articulating surfaces
• Bony surface of head of the condyle is made of dense
compact bone with cancellous bone in the center.
• Articular fossa is lined by a thin layer of compact
bone.
• Articular eminence has a core of cancellous bone
covered by a layer of compact bone.

9. Articular fibrous covering
• Composed of 4 layers
1. Articular zone
2. Proliferative zone
3. Fibrocartilagenous zone
4. Calcified zone

10. Articlular zone
• Most superficial zone
• Composed of fibrous tissue
consisting of fibroblasts
scattered in a dense type 1
collagen fibers arranged in
bundles

11. Proliferative zone
• Second zone
• Highly cellular and composed
of undifferentiated
mesenchymal tissue
• This layer is responsible
for proliferation of
articular capsule in response
to functional demand

12. Fibrocartilagenous zone
• Bundles of collagen fibers arranged in a crossing
pattern and some in radiating pattern
• This layer provides resistance against compressive
or lateral surfaces

13. Calcified zone
• Made up of chondrocytes and chondroblasts
distributed throughout the articular cartilage
• This zone provides an active site for remodeling
activity as endosteal bone growth proceeds

14. Articular fibrous covering of
articular fossa

15. Articular capsule
• It is a dense collagenous sheet or sac that encloses
the joint space
• It is circumferentially attached to the rim of
glenoid fossa and articular eminence above and to
the neck of the condyle below

16. Histology of articular capsule
• Composed of two layers:
1. Outer fibrous layer of dense connective tissue
2. Inner layer termed synovial membrane

18. Synovial membrane
• Lines the inner aspect of fibrous capsule and
therefore forms the lining of joint cavity
• Consists of two layers:
1. Inner cellular intimal layer
2. Highly Vascular subintimal layer

19. Subintimal layer
• Composed of loose connective tissue containing
blood vessels, scattered fibroblasts, macrophages,
mast cells.

20. Intimal layer
• Consists of few layers (1-4) of synovial cells,
distributed in an amorphous intercellular matrix.
• These cells are not attached to each other and do
not form a continuous layer.
• Three types of cells are mainly seen

21. • Type A cells: macrophage like cells:
- have an irregular outline with plasma membrane
- cytoplasm is rich in mitochondria, golgi apparatus,
lysosomes
- type A cells have phagocytic properties

22. Type B cells (fibroblast like cells or secretory
cells)
• These cells are rich in RER and involved in
synthesis of hyaluronic acid which is added to
synovial fluid
Third type: cells have cellular morphology between
the other two types

24. Synovial fluid
• Joint cavity contains appxomiately 1ml of SF
• Formed by diffusion of plasma from the rich
capillaries of subintimal layer
• Proteins and hyaluronic acid secreted by
fibroblasts is also added
• Also contain few synovial cells and defense cells

25. Functions of synovial membrane
1. Lubrication: by providing a fluid environment for
the joint
2. Nutritive: provides nutrition to avascular fibrous
covering and center part of articular disc
3. Regulatory: controls movement of nutrients,
electrolytes

26. 4. Secretory: intimal cells secrete proteins and
hyaluronic acid to the synovial fluid
5. Phagocytic: Type A cells are phagocytic and
therefore help in debriding

27. ARTICULAR DISC
 Biconcave oval
structure located
between the condyle
and articular surface of
temporal bone.
 The disc is thinnest at
the central zone and
thicker in posterior and
anterior border zone

28.  Thick posterior and anterior band act as wedge
giving the disc a self seating capacity with the
condyle functioning against the intermediate zone
 Contour of the disc with in the thick bands helps to
prevent displacement of the disc from the condyle
during translation

29. • Four distinct regions namely:
1. Anterior band
2. Intermediate zone
3. Posterior zone
4. Bilaminar region

30. • The shape of articular disc conforms to the articular
surfaces which it is opposed
• The upper contour of the disc is concave in the
anterior region to fit under articular eminence.
• Convex posteriorly and loosely rest against articular
fossa
• Lower surface of disc is concave thus adapting the
upper surface of mandibular condyle

32. • Articular disc divides the joint space into
1. Upper compartment called Temporo-discal
which is between disc and temporal fossa
2. Lower compartment called condylo-discal
situated between disc and condyle

33. • Upper joint space allows translatory movement
anteriorly along the slopes of the articular
eminence to produce an anterior and inferior
movement of the jaw.
• Lower joint space allows the rotational movement
of head of the condyle which is also called as hinge
movement

34. Histology of articular disc
• Composed of dense fibrous tissue with tightly
packed interlacing collagen fibers.
• The fibroblasts are elongated with long processes.
• Few elastic fibers may be present
• The center portion of disc is devoid of blood
vessels and nerves while periphery is highly
vascular.

35. Functions of articular disc
• Divide the joint cavity into two compartments and
therefore allowing different types of mandibular
movements
• Since it is soft tissue component between two hard
tissue components of the joint, it prevents rubbing
or friction between these components

36. • Acts as a cushion against heavy load and therefore
helps in shock abosrption
• Stabilizes the condyle by filling up the space
between the articulating surfaces
• Proprioceptive nerve fibers present in the anterior
and posterior portion of disc help in regulating
movements of condyle

37. Ligaments
• Capsular ligament or articular capsule
• Temporomandibular ligament
• Accessory ligaments

38. Temporomandibular ligament or
lateral ligament
• Fan shaped ligament functioning to reinforce the
lateral wall of the articular capsule
• Limits the lateral and posterior movements of the
joint

39. • It is attached superiorly to the articular tubercle and
runs posterio inferiorly and laterally to attach to
neck of mandible

40. Accessory ligaments
• Two accessory ligaments are:
1. Sphenomandibular ligament:
• Extends form the spine of sphenoid to the lingula and
lower margin of mandibular foramen
• It represents residual perichondrium of meckel’s
cartilage
• Overmovements of mandible is limited by this
ligament

41. 2. Stylomanibular ligament:
• Extends from lateral border of the styloid process
to the posterior border of ramus of the manible
above its angle
• It represents the thickened part of the investing
layer of deep fascia of the neck
• Helps in limiting protrusive movement

42. TMJ movements
• Rotation (hinge movements)
• Translation (gliding movements)