Waxman S G
Muscle Nerve. 1980 Mar-Apr;3(2):141-50. doi: 10.1002/mus.880030207.
This article reviews the determinants of conduction velocity in myelinated nerve fibers. For fibers exhibiting geometric similarity, conduction velocity is nearly proportional to diameter. However, in classes of geometrically similar fibers, myelin thickness and internode distance are linearly related to diameter. Therefore, it is not possible to assess the relative contributions of each of these factors. The relative effects of changes in each of these parameters on conduction velocity can be assessed from studies on fibers representing different similarity classes or from theoretical parametric studies. These studies show that for a fixed axon diameter, conduction velocity increases with myelin thickness. For a fixed total fiber diameter, there is an optimal ratio of axon diameter to total fiber diameter (and therefore to myelin thickness) at which conduction velocity is maximized. Conduction velocity is dependent on internode distance, with a broad maximum centered around the value observed in normal peripheral fibers. Conduction velocity is also dependent on temperature and the properties of the axonal milieu. Thus, the conduction speed of any given fiber reflects a number of parameters and is not determined by any single structural characteristic.
本文综述了有髓神经纤维传导速度的决定因素。对于表现出几何相似性的纤维，传导速度几乎与直径成正比。然而，在几何相似的纤维类别中，髓鞘厚度和节间距离与直径呈线性相关。因此，不可能评估这些因素各自的相对贡献。这些参数中每个参数变化对传导速度的相对影响可以通过对代表不同相似性类别的纤维的研究或理论参数研究来评估。这些研究表明，对于固定的轴突直径，传导速度随髓鞘厚度增加而增加。对于固定的总纤维直径，存在一个轴突直径与总纤维直径（因此与髓鞘厚度）的最佳比例，此时传导速度最大。传导速度取决于节间距离，在正常外周纤维中观察到的值周围有一个宽泛的最大值。传导速度还取决于温度和轴突内环境的特性。因此，任何给定纤维的传导速度反映了多个参数，并非由任何单一结构特征决定。
