If the anterior attic bone plate and its mucous fold become a bony diaphragm, it is easy to induce epitympamic cholesteatoma in addition to the block of tympanic isthmus.

• 该骨板平均长度5?2mm，平均厚度1?1mm，上鼓室前骨板及其附着的粘膜皱襞随乳突气化的不同，而形态不同，若形成骨性骨膜，易于使鼓岬阻塞的病人出现上鼓室负压，诱发上鼓室胆脂瘤。