[Bulla ethmoidalis uncinata: theoretical and practical implications]

The authors describe the previously unknown morphological structure, bulla ethmoidalis uncinata, located at the medial plate of ethmoidal labyrinth that forms the upper part of the lateral wall of the nasal cavity in the region of middle nasal meatus. It was shown that the absence of semilunar hiatus in the nasal cavity may be responsible for fronto-nasal communication through the infundibular opening or the crooked fronto-nasal duct. The discovery of bulla ethmoidalis uncinata substantially extends our knowledge of the structure of human nasal cavity.