The round window has become a subject of interest recently as a route to treat inner ear diseases.
A study of the anatomy of the round window niche, round .window niche membrane and round window membrane was performed in 205 temporal bones.
1. The round window niche was examined under an operating microscope to determine the presence or absence of the round window niche membrane. Of 100 adult temporal bones, 30 had clear round window niches without round window niche membrane (open type), and 70 had round window niche membranes. The round window niche membranes were classified into three types. The closed type round window niche membrane covers the round window niche without any perforation. The perforated type had one or more perforations and the reticulated type had a lace-like membrane.
2. The measurement of the round window niche and round window membrane was performed by LUZEX 500. The round window niche (32 ears): area 2.85±0.78mm2, maximum length 2.30±0.37mm, width 1.77±0.28mm, superior wall 1.76±0.28mm, anterior wall 1.95±0.34mm, posterior wall 2.08±0.33mm. The round window membrane (45 ears): area 3.56±0.91mm2, maximum length 2.50±0.06mm, width 1.95±0.28mm.
3. The round window membrane consists of 3 layers: the outer layer, middle layer and inner layer. The middle layer occupies the largest part of the membrane (thickness 50-70μm). Collagen fibers in the middle layer run from the crista semilunaris to the margin of the round window like a fan. The round window niche membrane also consists of three layers: epithelial layers and subepithelial connective tissue layer. The latter loosely contains collagen fibers, fibroblasts and capillaries. Thickness of the niche membrane is 15-150μm.
4. The round window membrane is mathematically expressed and is displayed as a computergraphic.
