Final answer:
The natural arch of the eyebrow follows the frontal bone, which forms the supraorbital margin of the orbit and creates rounded brow ridges.
Step-by-step explanation:
The natural arch of the eyebrow or the curved line of the eye socket follows the frontal bone. The zygomatic bone, also known as the cheekbone, is indeed involved in forming the lateral wall of the orbit and the lateral-inferior margins of the anterior orbital opening.
However, the natural arch that's being referred to in the question is above this, where the frontal bone forms the supraorbital margin of the orbit and is thickened above each margin, creating the rounded brow ridges.