TMJ

• Joint


  From Latin verb Jungers which means to join
• Articulation


  From Latin term articulare which means to connect
• TMJ


  Articulation between the squamous part of temporal bone & the head of the condyle
• Other terms for TMJ

  • Temporomandibular articulation
  • Mandibular joint
  • Mandibular articulation
  • Craniomandibular articulation
• TMJ


  Ginglymo-arthrodial joint
• Gliding type


  • Occurs between the articular disk & articular surface of temporal bone
• Hinge type


  • Occurs between the inferior surface of the anterior disk & head of the condyle
• Gliding motion


  In the upper compartment of the joint between the disc and the temporal bone
• Hinge movement


  In the lower compartment of the joint between the disc and the condyle
• Temporal bone portion


  • Posterior articular fossa (mandibular fossa)
  • Anterior articular tubercle
• Bony components of TMJ

  • Head of the condyle
  • Articular tubercle
  • Glenoid fossa wall
• Fibrous components


  • Articular fibrocartilage
  • Articular disk
  • Articular capsule
• Outer layer of capsule


  Firm fibrous tissue reinforced by the ligaments associated with the joint
• Inner layer of capsule (synovial membrane)


  Thin connective tissue & contains blood vessels & nerves
• Synovial fluid


  Lubricates the joint & furnishes nourishment to joint parts that are without a blood supply: the fibrous covering of the articulating surfaces of the bones & the center of the disc
• Disc


  Composed of fibrous connective tissue
• Disc in older persons

  May have a few chondrocytes (cartilage cells)
• Anterior & posterior borders of disc

  Thin in the center & thick at the
• Center of disc has no blood supply
• Articular fossa & eminence on temporal bone


  Covered with fibrous connective tissue
• Posterior border of eminence


  Fibrous layer is thicker than in the articular fossa. There are no blood vessels or nerves in this covering
• Mandibular condyle


  Articulating surface is covered with fibrous connective tissue similar to that covering the temporal bone area
• A few chondrocytes may be found in the fibrous layer on the mandibular condyle, but there are no blood vessels or nerves
• Uppermost part of condyle curvature

  Fibrous layer is very thick
• Fibrous connective tissue


  Covering of the bone surfaces of the TMJ that makes this joint different from most other such articulations
• Hyaline cartilage


  Most movable joints have a surface of this rather than of fibrous connective tissue
• Hyaline cartilage beneath fibrous covering of fetal condyle


  Growth center, & in this location it increases almost entirely by appositional growth (new cartilage added to existing cartilage edges)
• Bone


  Gradually replaces the cartilage as development continues
• Compact bone


  Forms under the fibrous connective tissue covering
• Trabecular bone


  Replaces the cartilage within the mandibular head
• Condyle takes on the adult histologic form
• Growth of the condylar cartilage

  Affects the height & length of the mandible & influences the shape of the entire face
• TM capsule


  Reinforced by ligamentous thickening
• Ligaments


  Nonelastic collagenous structures that restrict & limit the movements a joint can make
• Lateral or Temporomandibular ligament

  Fan-shaped reinforcement of the lateral wall of the capsule running obliquely backward & downward from the lateral aspect of the articular eminence to the posterior aspect of the condylar neck
• Lateral or Temporomandibular ligament


  Prevents lateral & medial dislocation of the opposite joint
• Parts of Lateral or Temporomandibular ligament


  • Outer oblique portion
  • Inner horizontal portion
• Outer oblique portion


  Arises from the outer surface of the articular eminence & extending backward & downward to insert into the outer surface of the condylar neck. Limits the amount of inferior displacement that can occur.
• Inner horizontal portion


  With the same origin but inserting into the lateral pole of the condyle & the lateral margin of the disk. Limits posterior displacement of the condyle & disk.
• TM joint


  Sliding "ball and socket" joint, whose parts work smoothly when you open and close your mouth