Which TMJ disorder is related to a displaced disc, dislocated jaw, or injury to the condyle (also malocclusion)?

• A. Internal Derangement
• B. Myofascial Pain
• C. Degenerative Arthropathy
• D. Ankylosis

Answer: (A)

The main idea here is a TMJ problem where the joint’s articular disc is out of its normal position relative to the condyle and fossa. When the disc is displaced, especially anteriorly, the jaw’s movement becomes abnormal, which can lead to malocclusion, jaw instability or locking, and sometimes pain. This overall pattern is what clinicians call internal derangement, because the dysfunction comes from the disc-condyle relationship being deranged rather than from muscle pain, wear-and-tear, or joint fusion.

To connect the pieces: a displaced disc or injury to the condyle disrupts how the condyle tracks inside the joint, altering bite and function. Myofascial pain involves muscles of mastication rather than the joint structure itself. Degenerative arthropathy refers to wear-related changes in the joint surfaces. Ankylosis means the joint is fused and movement is severely limited. The description given—displaced disc, dislocated jaw, and malocclusion—directly fits internal derangement.