Computed tomographic and anatomical analysis of the basal lamellas in the ethmoid sinus.

OBJECTIVES: To investigate the exact anatomical structure of the lamellas in the ethmoid sinus by computed tomography (CT) and anatomical analysis. STUDY DESIGN: Cadaver dissections and CT scans were used to compare lamellar structures and their radiological images. METHODS: Anatomical microdissection of 100 midsagittal sections from adult cadaver head specimens were examined and compared with those of sagittal CT scans at 1-mm intervals. RESULTS: The posteroinferior end of the uncinate process attaching to the inferior turbinate divided the fontanelle into the anterior and posterior portions in the majority of cases. The basal lamellas of the bulla ethmoidalis were subdivided into three major types. The posteroinferior portion of its basal lamella was connected to the lower horizontal portion of the third basal lamella in all cases. The anterior indentation of the third lamella was identified in nine cases, but there was no indentation in the posterior direction. The basal lamella of the superior turbinate was attached to the skull base superiorly either separately or fused to the third lamella, and its posteroinferior portion was attached to the lowest portion of the anterior wall of the sphenoid sinus. The supreme turbinate existed in 50 cases; however, its basal lamella was identified in only 15 cases. CONCLUSIONS: Our results indicate that the lamellas of the ethmoid sinus have relatively uniform patterns, although there is variability in shape. It is hoped that this study will provide surgeons with a more detailed structure of the basal lamellas for better surgical results and lower complication rates.