الفهرس 
Yasser Ibrahim Aglan
Middle ear compartmentsOnly 14 pages are availabe for public view
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Abstract
Middle ear couples sound energy to the cochlea. Ossicular chain serves as an acoustic transformer to match the impedance of the air to the much higher impedance of the cochlear fluids. Middle ear apparatus besides providing physical protection for cochlear fluids, also serves to couple sound preferentially to only one window of the cochlea. Thus producing a differential pressure between the windows required for the movement of the cochlear fluids (1). Both types of chronic suppurative otitis media, tubotympanic as well as atticoantral type may lead to erosion of the ossicular chain. This propensity for ossicular destruction is much greater in cases of atticoantral type, due to the presence of cholesteatoma and granulations (2). The lenticular process and long process of the incus is the most vulnerable part of whole ossicular chain to necrosis because it has a proximal narrow pedicle (3). The proposed mechanism for erosion in chronic middle ear inflammation is due to overproduction of cytokines, Tumor necrosis factor (TNF) alpha, interleukin-2, fibroblast growth factor, and platelet derived growth factor, which promote hypervascularisation, osteoclast activation and bone resorption causing ossicular damage. TNF-alpha also produces neovascularization and hence granulation tissue formation (3).