Summary Notes Kinesiology of the TMJ
CPP- Tight Clench
CP- limited opening
Dislocation- fracture of the mandible body is most common though mediolateral dislocation
most likely dislocation
Reminder: joint type- synovial joints with fibrocartilage
Two separate joint spaces
Superior joint space: Plane synovial joint between intra-articular disc and condylar fossa
Inferior joint space: Hinge synovial joint between intra-articular disc and mandibular condyle
Ligamentous support
Temporomandibular lig- Limits opening, retrusion and lateral deviation
Stylomandibular and sphenomandibular lig- suspends the mandible
Intra-articular disc- firmly attached medial lateral, loosely attached anterior posterior.
Painful clench without tongue depressor suggests discal or tissue involvement
Painful clench without tongue depressor suggests muscular involvement
Movements
Mandibular depression and elevation
Rotation at the inferior joint (anterior rotation of condyle on the disc aka roll and glide
in the opposite direction)
Gliding in the superior joint (disc and condyle move together anteriorly)
Mandibular Protrusion and retrusion
Translatory movement that only occurs in the superior joint (no rotation)
Limited retrusion
Lateral deviation
Observe condylar spinning ipsilaterally
Observe condylar translation contralaterally
Relationship with the cervical spine
Head carriage often affects position of the TMJ
Anterior head- TMJ protrusion (TMJ laxity and increased freeway space)
Military head/Retrusion- TMJ retrusion (Retrodiscal tissue damage and decreased freeway
space)
TMJ function can also be influenced by:
Bruxism
Hard objects cracking
Thumb sucking or mouth breathing
Lengthy dental procedures
Relevant muscles of the TMJ
Digastric (anterior belly mylohyoid, posterior belly facial nerve)
Medial and lateral Pterygoids (trigeminal n)
Lateral contracts concentrically during mandibular depression
Medial contracts concentrically in mouth closing
Temporalis and masseter (trigeminal n)
Assists in protrusion and elevation of mandible