Examination of sinus tympani, subtympanic sinus, and facial sinus with MicroCT

This study aimed to determine sinus tympani, subtympanic sinus (STS), facial sinus (FS) morphologies, and type distributions. Type distributions were based on their relations with the facial nerve (FN). A total of 20 right and 20 left temporal dry bones without physical deformation were scanned with a MicroCT device. All measurements were made using MicroCT programs from sections in the axial plane. For the FS, the average depth was measured as 3.485 mm without any classification, and 29 of the 40 bones had Type C radiological morphology. The mean depth for all sinus tympanicus was 2.646 mm, and 22 of the 40 bones had Type B morphology. For the STS, 29 out of 40 samples had no contact with the FN; regardless of the classification, the average depth was measured as 2.376 mm. We reveal the depths of the tympanic cavities and their relationship with the FN. The results of this study may benefit clinicians performing retrotympanum surgeries.