Anterior superior transcranial view of ethmoid sinuses, dura mater, and orbit. In this view, the five layers of the scalp are contained in the flap that has been reflected forward off the frontal bone. The deepest layer, the periosteum or pericranium is in view on the reflected flap. A large portion of the frontal bone has been removed to expose the outer, rough layer of the dura mater, the periosteal dura. This layer is largely fused with the inner smooth layer of dura mater, the meningeal dura, which faces the brain. Note also the trilaminar nature of the cut surface of the bone with its outer and inner tables of compact bone and the central diploe consisting of spongy bone and bone marrow. Anteriorly, near the midline, bone of the floor of the anterior cranial fossa has been removed to expose the roof of the ethmoid sinuses, which border medially with the nasal cavity, and laterally with the orbit. The superior margins of the orbits have been removed to show the orbital contents contained within their periorbital lining. Anterolaterally, the temporalis muscles have been reflected off their temporal fossae. Posterior to the frontal bone are the paired parietal bones. The coronal suture forms the fibrous joint connecting these bones. (Image courtesy of AL Rhoton, Jr.)