[The sagittal dimension of the sinus frontalis, its wall thickness, distance from the lamina cribrosa, the depth of the so-called olfactory groove and the ethmoidal canal].

The anterior and the posterior wall of the frontal sinus and its anterior-posterior depth on the deepest area were measured in the sagittal medial plan and 2 cm outside of the median. Also estimated were the distance between the posterior side of the anterior wall of the frontal sinus and the anterior border of the lamina cribrosa (mean value 17.4 mm). The depth of the olfactory rim was measured in the anterior, the middle, and the posterior third of the lamina cribrosa. There was measured also the lower surface of the lamina cribrosa and the level of the ethmoidal canals to the lamina cribrosa and its dehiscences.