Endoscopic exposure of frontal lobes. The dura of the planum sphenoidale has been opened to show the gyrus rectus, medial fronto-orbital gyrus, olfactory tract, fronto-orbital artery, and interhemispheric fissure. The dura of the olfactory sulci and cribriform plate remains intact. Note that the olfactory bulb, not seen here, is located behind the olfactory sulcus. (Image courtesy of JC Fernandez-Miranda)