TMJ CONSIDERATIONS

Picture1The Temporomandibular joint is part  of of the Stomatognathic System,  comprising teeth, jaws and associated soft tissues. It is referred to as TMJ. There are two TMJs, one on each side, working in unison.

The TMJ is a GINGLYMOARTHRODIAL joint, referring to its dual compartment structure and function (ginglymo and arthrodial).

The condyle articulates with the temporal bone in the mandibular fossa. These two bones are actually separated by an articular disc, which divides the TMJ into two distinct compartments.

The inferior compartment allows for rotation of the condylar head around an instantaneous axis of rotation, corresponding to the first 20 mm or so of the opening of the mouth.

After the mouth is open to this extent, the mouth can no longer open without the superior compartment of the TMJ becoming active. At this point, if the mouth continues to open, not only is the condylar head rotating within the lower compartment of the TMJ, but the entire apparatus (condylar head and articular disc) translates.

 

temporomandibular-joint-anatomy-and-its-prosthodontic-implications-35-638

MANDIBULAR DEPRESSION ARTHROKINETICS:

EARLY PHASE:  Rolling motion – first 2/3 of opening.  The mandible and meniscus move anterior together beneath the articular eminence while opening or closing.

LATE PHASE:  Gliding motion –  translation anteriorly, last 1/3 of mouth opening. It can also slide laterally.

Decreased Opening (3 finger test):

—Early phase: muscular, capsular, and/or disc. (Normal = 20-25mm)

—Late phase : capsular or disc.

Deviation:

—‘C-pattern’ of motion occurs if the joint hypomobility is due to internal derangement.

—The mandible deviates toward the involved side in the midrange of opening before returning to normal.

—‘S-pattern’ of movement while opening the mouth may indicate:

—Normal ROM –  muscle imbalance, with or w/out joint dysfunction.

—Decreased ROM – bilateral muscle imbalance and joint dysfunction /derangement.

Deflection: Lateral movement to one side from onset of opening. Congenital,  internal derangement, or possible ankylosis.

 

COMMON SIGNS & SYMPTOMS:

—CAPSULITIS: Pain with Mandibular Distraction.

—SYNOVITIS:  Capsulitis s/s + Mandibular Elevation pain.

—INTERNAL DERANGEMENT w/ REDUCTION:  Clicking in TMJ during mouth opening & protrusion. Lat. Movement clicking w/  Med/Lat displacement .

—INTERNAL DERANGEMENT w/out REDUCTION: Limited mouth opening @ 26-32mm. Limited protrusion.

—HYPERMOBILITY:  Audible, visible and/or palpable movement of the condyle(s) past the temporal eminence. If unilateral, the condition may be secondary to contralateral joint hypomobility.

 

EXAMINATION:

-Posture

-Kinematics of the Spine, especially the Cervical Spine

-Alignment of jaw

-Active ROM

-Jaw Opening Motion Palpation

-Joint Play

-TMJ muscle tension, tightness, trigger points, and shortening.

 

We cover how to treat dysfunctions found on each of these examination components in the TMJ adjusting seminar.

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