During assessment of jaw movement, which finding indicates the early phase is dominated by rotation of the condyles?

• A. Anterior translation
• B. Condylar rotation
• C. Lateral deviation
• D. Posterior glide

Answer: (B)

In the very first phase of opening the jaw, the motion is hinge-like: the condyles rotate within the mandibular fossae around a transverse axis, with little forward sliding. This rotational movement is the dominant pattern early on, before the condyles begin to glide anteriorly along the articular eminence. As opening increases, the movement shifts toward translation, where the condyles and disc slide forward, allowing more wide-mouth opening. So observing rotation as the primary early motion reflects this hinge-type opening. An anterior translation would occur later, lateral deviation relates to side-to-side excursion, and posterior glide is part of closing or seating movements rather than the initial opening.