Superior view of cerebrum. Anterior is directed toward the bottom of the image, posterior toward the top. The interhemispheric fissure is widened by retractors to reveal the pericallosal artery coursing along the superior surface of the corpus callosum, which it supplies. This artery is the distal continuation of the anterior cerebral artery. The superomedial portion of the frontal lobe is represented by the superior frontal gyrus, which extends from the frontal pole anteriorly to the precentral sulcus and gyrus posteriorly. The frontal poles have been elevated to expose the floor of the anterior cranial fossa. Most of this is formed by the frontal bone (a portion of the frontal sinus has been opened). The anterior midline is formed by the ethmoid bone, specifically the crista galli for attachment of the falx cerebri and the cribriform plate (lamina cribrosa) on which the olfactory bulbs rest. Posteriorly, the planum sphenoidale of the sphenoid bone is in view. The precentral gyrus or primary motor cortex is the posterior portion of the frontal lobe. It is separated from the postcentral gyrus or primary somatosensory cortex of the parietal lobe by the central sulcus. On the lateral surface of the head is the temporalis muscle overlying the temporal fossa and the external ear. (Image courtesy of PA Rubino)