Which of the following is NOT a border movement of the mandible?

Correct answer: D. Habitual (normal) closure

• A. Maximum protrusion is the anterior border of the envelope of motion.
• B. Maximum retrusion (retruded contact position) is the posterior border.
• C. The terminal hinge movement is the superior-posterior border, produced by pure rotation about the terminal hinge axis.
• D. Correct. HABITUAL CLOSURE is a functional movement that occurs WITHIN the envelope of motion, not at its edge. Border movements are the extreme, reproducible limits of mandibular travel — they are determined by ligaments and joint anatomy, which is exactly why they are reproducible and useful for articulator programming. Posselt's envelope is bounded by protrusion, retrusion, lateral extremes and the terminal hinge arc; ordinary chewing and closing paths lie inside it.