Definition: intra-articular and extra-articular processes may restrictjaw motion severely. Ankylosis of the TMJ is an intra-articular process characterized by fibrous,fibo- -osseous, or osseous obliteration(消失) of the joint space. Extracapsular causes of restricted jaw motion (pseudoankylosis) include but are not limited to coronoid-zygomatic fusion(融合), coronoid hypertropy, and muscular fibrosis