The mechanics of the middle-ear at static air pressures: the role of the ossicular joints, the function of the middle-ear muscles and the behaviour of stapedial prostheses.
The mechanics of the middle-ear at static air pressures: the role of the ossicular joints, the function of the middle-ear muscles and the behaviour of stapedial prostheses.
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静态气压下中耳的力学：听骨关节的作用、中耳肌肉的功能和镫骨假体的行为。
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发表时间：
1988
期刊：
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通讯作者：
K. Hüttenbrink
中科院分区：
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作者：
K. Hüttenbrink
在一项实验研究中，用显微镜和放射放大技术对听骨链在静态气压变化过程中的力学行为进行了分析。几个初步实验用于确定方法学问题，如刺激伪影、存储程序、制备缺陷、开放的中耳腔的气垫效应缺失、迷路压力缺失、光轴与中耳结构的关系以及测量值的统计重复性。外耳道内静气压的变化范围从0到+/-400 mm H2O，会导致锤骨向内向外运动。在正常的中耳，这种运动的方向在听骨链内改变为豆状突起的主要向上-向下方向，这是由于截骨-踝关节的滑动作用。这会导致砧骨关节(IS)表面的滑动运动。通过这种方式，距骨和内耳与鼓膜和锤骨的过度位移分离。这种运动模式的改变解释了许多以前的听骨振动的结果，这些结果是由非生理性的高声压引起的，就像V.Békésy对倾斜踏板的描述一样。然而，如果实验性强直取消了IM关节的滑动功能，这种运动模式就会完全改变。在这种情况下，砧骨和砧骨的主要运动方向也是向内和向外的。到目前为止，这种运动方式一直是听骨链力学中被普遍接受的概念。这种同向运动也发生在颞骨准备的渐进性锻炼中，可以解释为IM关节的关节囊韧带干燥和收缩。因此，可以想象，我们对听骨链的力学概念在一定程度上是基于对不够潮湿的颞骨准备的实验，因为摘除的方法学问题直到最近几十年才为人所知。在进一步的静气压实验中，对重建的听骨链的力学性能进行了研究，即鼓室成形术和砧骨假体。在柱状链重建中，距骨的位移等于强直的IM关节的测量值。这种移位受到环状韧带强度的限制，然而，如果是腓骨假体，环状韧带的功能就被消除了。现在，位移受到脚踏板穿孔处活塞摩擦的限制。
In an experimental study, the mechanical behaviour of the ossicle-chain during changes of the static air pressure was analyzed microscopically and with a radiographic magnification technique in temporal bone preparations. Several preliminary experiments served to pinpoint methodological problems, like exsiccation-artifacts, storage procedures, preparation defects, missing air-cushion effect with the opened middle-ear cavity, absent labyrinthine pressure, relation of the optical axis to middle-ear structures and statistical reproducibility of the measured values. Variations of the static air pressure in the external ear canal ranging from 0 to +/- 400 mmH2O induce an inward-outward movement of the malleus. In the regular middle-ear, the direction of this movement is changed within the ossicular chain into a predominantly upward-downward direction of the lenticular process, due to a gliding function of the incudo-malleal (IM) joint. This results in a gliding movement of the surfaces of the incudostapedial joint (IS). In this way, the stapes and the inner-ear are decoupled from the excessive displacements of the drum membrane and malleus. This change in the mode of motion explains many former results of ossicle vibration, aroused by unphysiologically high sound pressures, like v. Békésy's description of the tilting footplate. This mode of motion, however, changes completely if the gliding function of the IM-joint is cancelled by experimental ankylosis. In that case, the predominant direction of movement at the incus and stapes is inward and outward, too. This mode of motion has been the generally accepted concept of the ossicle-chain mechanics up to now. This isodirectional motion also occurs with progressive exsiccation of the temporal bone preparations, explicable with drying and shrinking of the capsular ligament of the IM-joint. It is conceivable, therefore, that our concepts of the mechanics of the ossicle-chain were partly based on experiments with insufficiently moistened temporal bone preparations, as the methodological problem of the exsiccation became known only during recent decades. In further experiments with static air pressure, the mechanics of the reconstructed ossicle-chain, i.e. tympanoplasty and stapedial prostheses, were studied. In the columella-like chain reconstruction, the displacement of the stapes equals the values measured with the ankylosed IM-joint. This displacement is limited by the strength of the annular ligament, whose function, however, is eliminated in the case of stapedial prostheses. Now the displacement is limited by the friction of the piston at the perforation in the footplate.(ABSTRACT TRUNCATED AT 400 WORDS)