Final answer:
In an axio-lateral temporomandibular articulation image, the side opposite to the film is best demonstrated as it shows the active lateral movement away from the midline of the jaw.
Step-by-step explanation:
When doing an axio-lateral temporomandibular articulation image, the side best demonstrated is the one opposite the film. An axio-lateral view is taken to evaluate the temporomandibular joint (TMJ), which is responsible for various movements including opening and closing the mouth, as well as lateral excursion. Lateral excursion involves side-to-side movement, or the moving of the mandible away from the midline toward either the right or left side. During this examination, the side of the mandible closest to the film is placed in a position of medial excursion, meaning that it is closer to the midline of the jaw, and hence it is the opposite side that is actively moving laterally away from the midline and is better visualized.