[Round window area temporal bone section versus CT].

Objective: To locate round window area and its related structure on auris transection and CT for anatomical evidence of image diagnosis and clinical operation.

Methods: Fifteen normal head specimen fixed with 10% dehyde were scanned by high-resolution computed tomography on canthomeatal line. CT image (depth 1.00 mm, thick 1.00 mm) was obtained. Temporal bone-centered tissues were taken, decalcified, desiccated and socked with collodion, then embedded and made into sequential transactions (thick 1.00 mm). Lower surface of section was observed by both naked eyes and microscope, then scanned and photographed. Versus CT image, auditory ossicle, osseous semicircular canals, vestibule, round window, niche, cochlea, pyramidal eminence, internal acoustic meatus and cochlear aqueduct were identified respectively.

Results: There were 18-22 layers of temporal transection on CT image. Round window and round window niche always appeared on the 10th layer (R) and the 11th layer (L). The mean of the depth of anterior wall was 0.92 mm (R) and 0.90 mm (L), and depth 1.89 mm (R) and 2.04 mm (L). The average distance from niche to jugular fossa wall was 2.10 mm (R) and 2.39 mm (L). No significant difference among of thickness, depth and distance from niche to jugular fossa wall.

Conclusions: Temporal bone transection specimen had a clear picture of anatomical position between round window area and its related structure. Versus CT, the result contributed to image diagnosis and operation on auris diseases.