Karlan M S, Enoch J M
Otolaryngol Head Neck Surg (1979). 1979 Nov-Dec;87(6):904-10. doi: 10.1177/019459987908700628.
Dissection of the antrum requires judicious visualization of the tegmen, horizontal canal, incus, and facial nerve. Inadvertent contact with the incus by the power drill may cause significant acoustic trauma. An effective "early warning device" accurately predicting exposure of the incus may be constructed with the saline irrigation fluid. The formation of the meniscus at the antrum permits visualization of the image of the incus around the corner of the bony canal wall overhang. A thin-lens model of this phenomenon has been created for first-order analysis of the optics, and it provides useful criteria for using this image. Image minification, displacement, and distortion were analyzed. A more complex model was then created to assess the impact of changing meniscus shape. The latter helped in understanding an added "swinging-door effect" noted as the meniscus was altered. The model predicted accurately the phenomena as observed in the temporal bone preparation. Illustrative examples of the optics and photographic demonstrations of the phenomena are presented.
上颌窦的解剖需要审慎观察鼓室盖、水平半规管、砧骨和面神经。动力钻不慎接触砧骨可能会导致严重的听觉创伤。利用生理盐水冲洗液可以构建一种能够准确预测砧骨暴露的有效“早期预警装置”。上颌窦处弯月面的形成使得能够看到悬于骨管壁拐角处的砧骨影像。已建立此现象的薄透镜模型用于光学的一阶分析，并为使用该影像提供了有用的标准。分析了影像的缩小、位移和畸变。然后创建了一个更复杂的模型来评估弯月面形状变化的影响。后者有助于理解随着弯月面改变而出现的额外“旋转门效应”。该模型准确预测了在颞骨标本中观察到的现象。文中给出了该现象的光学示例及摄影演示。
