Njeugna E, Eichhorn J L, Kopp C, Harlicot P
Centre Universitaire de Douala, Cameroun.
J Vestib Res. 1992 Fall;2(3):227-34.
Mechanical aspects of the ampullar diaphragm, that is the crista ampullaris and the cupula, related to its thickness, are studied by a numerical method. Numerical methods are able to go beyond the limits of analytical approaches and are the only methods able to take into account this thickness. A finite elements method is applied to the median plane slice of the ampullar diaphragm. One assumes that the cupula sticks firmly without slipping, to the ampullar wall and to the crista ampullaris. The computation takes into account the pressures on the liquid interfaces and the deformations of the ampulla. So the volume swept over by the cupula during quasi-static deformations can be evaluated and the global elasticity coefficient of the human cupula can be calculated. The related value of the long time constant of the semicircular canal is close to the value obtained when measuring, in vivo, the activity on the vestibular nerve in animals. The thick cupula model clearly shows two different spatial distributions of strain on the hairs of the sensory cells, leading to a discrimination between the vestibular inflating pressure and the transcupular pressure difference. This result matches recent neurophysiological data and brings a new insight in the mechanics of the vestibular angular accelerometer and its regulation.
通过数值方法研究壶腹隔膜的力学特性，即壶腹嵴和终帽与其厚度的关系。数值方法能够突破解析方法的局限，是唯一能够考虑该厚度的方法。将有限元方法应用于壶腹隔膜的中间平面切片。假定终帽牢固地附着于壶腹壁和壶腹嵴，不发生滑动。计算考虑了液体界面上的压力以及壶腹的变形。这样就可以评估终帽在准静态变形过程中扫过的体积，并计算出人体终帽的整体弹性系数。半规管长时间常数的相关值与在动物体内测量前庭神经活动时获得的值相近。厚终帽模型清楚地显示了感觉细胞毛上两种不同的应变空间分布，从而区分了前庭膨胀压力和跨终帽压力差。这一结果与最近的神经生理学数据相符，并为前庭角加速度计的力学及其调节带来了新的见解。
