The Roof of the Anterior Ethmoid: A Place of Least Resistance in the Skull Base

Abstract

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 in the vicinity of the anterior ethmoidal artery, especially where it leaves the dome of the ethmoid medially to reach the ethmoidal sulcus in the olfactory fossa. Complete ethmoidal specimens were investigated by means of histologic serial sections in the frontal plane. Forty anterior ethmoidal arteries were anatomically prepared. Special features of their topography including 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 were studied with regard to their surgical relevance. Of utmost importance is the fact that the bone in the vicinity of the ethmoidal sulcus is up to 10 times thinner than the neighboring roof of the ethmoid sinus. Coronal CT scans demonstrating this most critical point with all its many possible variations are found to be invaluable for the preoperative planning of endoscopic or other ethmoid surgery.