Disk Displacement Disorders
In a normally functioning TMJ the condyle functions in both a hinge and a sliding fashion. Ouring full openingthe condyle not only rotates on a hinge axis but translates forward to a position near the most Inferior portion of the articular eminence (Fig.30-1l). During function the biconcave disk remains interpositioned between the condyle and fossa, with the condyle remaining against the thin intermediate zone during all phases
of opening and closing. .vntcrior disk displacement with reduction, In ante-. rior disk displacement the disk is positioned anterior and medial to the condyle in the dosed. position. During opening the condyle moves over the posterior band of the’ disk and eventually returns to the normal condyle
. and disk relationship, resting on the thin Intermediate .zone. During closing the condyle then slips posteriorly , and rests on the retrodlscal tissue, with the disk returning to the anterior, medially displaced position (Fig. 30-12).
Examination of the patient usually reveals joint ten-derness, and muscle. tenderness may also exist. Joint noise (i.e., clicking) is commonly heard with opening, when -the condyle moves from the. area posterior to the disk into the thin concave area in the middle of the disk. In some :cases clicking can beheard or palpated during.