Final answer:
The frontal bone forms the forehead, the front of the skull's roof, and the roof of the eye socket. It features the glabella, supraorbital margin, and supraorbital foramen, and contributes to the structure and protection of the cranial cavity and orbit.
Step-by-step explanation:
The bone that forms the forehead, the front of the skull's roof, and the roof of the eye socket is the frontal bone. This single bone not only shapes the forehead but also plays a critical role in forming the upper part of the skull, including the eye sockets. One notable feature on the frontal bone is the glabella, a slight depression located between the eyebrows.
Apart from giving structure to the forehead, the frontal bone contributes to the supraorbital margin of the orbit. Just above this margin, the bone thickens, forming the brow ridges, which tend to be more prominent in males. The supraorbital foramen is an opening near the middle of this margin that allows for the passage of a sensory nerve to the forehead. Internally, the frontal bone extends to the back, forming the floor of the anterior cranial cavity and the roof of the orbit. Thus, the importance of the frontal bone extends well beyond aesthetics to functional aspects such as protecting the brain and providing cavities for essential sensory organs like the eyes.