Bhide A
Arch Otolaryngol. 1977 Dec;103(12):707-11. doi: 10.1001/archotol.1977.00780290043004.
The tympanic membrane meets the posterosuperior bony canal wall at a wide angle and thus makes the posterosuperior quadrant of the eardrum the most vulnerable part against the thrust effect of the air column in the external auditory canal compared with the rest of the pars tensa. The air column thrust effect becomes active when there is a decrease in the middle ear pressure because of Eustachian tube obstruction. The medial displacement of the eardrum exposes the posterosuperior quadrant of the eardrum to the venturi effect in the isthmus tympanicus posticus and the region below. The retraction pocket is the end result.
鼓膜与后上骨质耳道壁呈宽角相交，因此与紧张部的其他部分相比，鼓膜的后上象限在外耳道气柱的推力作用下是最脆弱的部分。当中耳压力因咽鼓管阻塞而降低时，气柱推力作用就会变得活跃。鼓膜的内侧移位使鼓膜的后上象限暴露于鼓室后峡及以下区域的文丘里效应中。最终形成内陷袋。
