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 sideCervical vertebrae
See: Back and Spinal Cord-Bones and Ligaments