In normal TMJ opening, what is the correct sequence of arthrokinematics?

• A. Anterior rotation followed by posterior translation
• B. Posterior rotation followed by anterior translation
• C. Both posterior rotation and translation
• D. Lateral translation followed by medial rotation

Answer: (B)

In normal temporomandibular joint (TMJ) opening, the correct sequence involves posterior rotation followed by anterior translation. Initially, as the jaw begins to open, the mandibular condyle rotates posteriorly around a horizontal axis, which is an essential component of the initial phase of mouth opening. This rotation occurs primarily within the glenoid fossa of the temporal bone and sets the stage for subsequent movements.

Once this posterior rotation phase is completed, the movement transitions into anterior translation, where the condyle glides forward along the articular surfaces. This translation effectively allows for further mouth opening and is crucial for efficient jaw function. The anterior translation occurs over the articular disc, facilitating the necessary space for the mouth to open fully while maintaining proper joint mechanics.

Understanding this sequence is important in the evaluation and treatment of TMJ disorders, as deviations from this norm can indicate dysfunction or pathology within the joint. Recognition of the correct arthrokinematic movements aids clinicians in diagnosing issues related to restricted motion or pain during TMJ function.