CASE 4 — Same patient: When passively stretched 5 mm beyond maximum opening, the patient begins to feel pain. What is the most likely source?

Correct answer: C. Left articular disc displacement

• A. A right disc problem would cause deviation to the right, not the left.
• B. DJD (osteoarthritis) typically causes crepitus and pain with loading rather than specifically at end-range passive stretch.
• C. The deviation is to the left, indicating restricted left condylar translation (consistent with left disc displacement without reduction). Passive stretching beyond the deviation point stresses the restricted left TMJ, causing pain from the displaced left articular disc and joint structures.
• D. Muscle pain (myalgia) causes pain with stretch, but given the mechanical deviation pattern, articular disc displacement is the more specific diagnosis.