Final answer:
The lateral border of the orbit is formed by the zygomatic bone, which is part of the orbit's supporting structure and crucial for lateral peripheral vision.
Step-by-step explanation:
The lateral border of the orbit is formed by the zygomatic bone. This is the bony section on the side of the skull that contributes to the outer wall and lateral floor of the orbit, the bony socket that houses the eyeball.
Along with the zygomatic bone, the orbit's structure is supported by six other skull bones, but for the lateral border specifically, the zygomatic bone is key. Protecting and providing structural support to the eye, this area is significant for its role in ensuring lateral peripheral vision due to the orbit's divergent shape from the midline at a 45° angle.