Advances in surgical techniques and instrumentations, utilization of the imaging tools, and understanding the regional anatomy have served to make functional operations with less complications in the paranasal sinus area. In the context of this article, some of these anatomical structures and their variations were reviewed through images. These structures were as follows: course of the anterior ethmoidal artery; roof of the ethmoid; lamina papyracea; uncinate process; optic nerve; and internal carotid artery.