Abstract
A total of 53 anatomical specimens of the posterior ethmoid and the adjacent anterior sphenoid sinus wall were examined in reference to the operative guidelines for endonasal sphenoidotomy. Six anatomical points of measurement were defined for clinical orientation, and both the absolute and the relative widths of each third (i.e. of each of three vertical sections) of the pars nasalis and the pars ethmoidalis of the anterior sphenoid sinus wall determined.
The choana proved to be the most valuable regional anatomic landmark. In 43 cases (41%), a pervading ethmoidal cell was found, extending superiorly and medically all the way up to the nasal septum. In contrast with certain guidelines reported in the literature, 18% of the specimen (sides) showed a wider pars nasalis in the vertical middle third of the anterior sphenoid sinus wall as compared to the adjacent pars ethmoidalis. The thickness of the bone in the anterior wall was similar in both areas. The present measurements support Wigand's recommendation (1990) that the anterior sphenoid sinus wall be perforated paramedially, 10 mm superiorly to the choana.
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