Microsurgical anatomy of the ethmoid.

A description of the constant landmarks of the ethmoidal labyrinth is proposed, based on data from micro-dissection, endoscopy, computed tomography and histology in 12 subjects. In accord with surgical procedure, the identification of these landmarks follows the lateral orbital and superior cranio-frontal aspects. The uncinate process, ethmoidal bulla, middle nasal concha and their septal roots, and the upper wall of the ethmoidal labyrinth in continuity with that of the sphenoidal sinus, form the definitive landmarks for endonasal ethmoidectomy under endoscopic monitoring.