[The roof of the anterior ethmoid: a locus minoris resistentiae in the skull base].

Because of its special anatomic features, the roof of the anterior ethmoid is a preferred area for frontobasal fractures as well as an area of hazard during ethmoid surgery. As clinical experience proves, the most critical area for lesions to occur is the vicinity of the anterior ethmoidal artery, especially where this leaves the dome of the ethmoid medially to reach the ethmoidal sulcus in the olfactory fossa. Complete ethmoidal specimen were investigated by the means of serial histological sections in the frontal plane. 40 anterior ethmoidal arteries were anatomically prepared and the special features of their topography like connection with the dura, fixation of the dura to the bone of the skull base and the variations of the thickness of the surrounding bony wall studied with regard to their surgical relevance. Not the dome of the ethmoidal roof proves to be the most critical point for lesions to occur, but the area where the anterior ethmoidal artery leaves the ethmoid medially, to enter the olfactory fossa. Here, the bone is tenfold thinner than at the very roof of the ethmoid.