Temporomandibular Joint

Temporomandibular Joint

[Plate 18, Temporomandibular Joint]

The mandible articulates with the temporal bone and in chewing or speaking, it is only the mandible or lower jaw that moves; the upper jaw or maxilla remains stationary. The teeth are contained in the alveolar portion of the mandible.

• Articulation between condylar process of mandible, articular tubercle of temporal bone, and mandibular fossa
• Modified hinge-type synovial joint
• Contains fibrocartilaginous disc, which divides joint cavity into two compartments
  • Gliding movements (protrusion and retrusion/retraction) occur in upper compartment
  • Hinge movements (depression and elevation) occur in lower compartment
• Stabilized by three ligaments:
  • Lateral temporomandibular ligament
    • Lateral thickened parts of articular capsule
    • Prevent posterior dislocation of joint
  • Sphenomandibular ligament
    • Primary passive support
    • Runs from spine of sphenoid to lingual of mandible
    • Serves as swinging hinge and check ligament
  • Stylomandibular ligament
    • Thickening in capsule of parotid gland
    • Runs from styloid process to angle of mandible
• Movements
  • Depression-suprahyoid and infrahyoid muscles, gravity
  • Elevation-temporalis, masseter, and medial pterygoid muscles
  • Protrusion-lateral pterygoid, masseter, medial pterygoid
  • Retraction/retraction-temporalis, masseter
  • Side to side grinding-retractors of same side, protruders of opposite side