Openings in the Roof of the Ethmoidal Labyrinth

Abstract

During the period from 9 to 35 years of age, the ethmoidal cells form completely or partly the bottom of the anterior cranial fossa on both sides of the cribriform plate. These cells, not covered by the frontal bone, form a thin bony wall covered by the dura mater. This roof may show different shapes. In our material, consisting of 32 specimens from human skulls, the following variations were found: (1) openings with a smooth margin; (2) rarefactions; (3) openings with an irregular margin, and (4) cells with a thin wall. The openings with a smooth margin (5 specimens) had dimensions of 2–10 mm. They occurred as single or multiple formations on one or both sides of the ethmoidal roof. Rarefactions and openings with an irregular margin were found in seven specimens. Openings with an irregular margin could be an artefact due to destruction or maceration. In the openings with a smooth margin, a close contact between nasal mucous membrane and dura has to be expected. This fact may play an important role in inflammation of the ethmoidal labyrinth as well as in surgical interventions. A thin wall of the roof of ethmoidal cells and rarefactions may also present a danger during surgery.