These striations are caused by the arrangement of the protein molecules within the fibers that produce shortening or contraction of the fiber.

这些横纹是由纤维内使其收缩的蛋白质分子排列而形成的。

Skeletal muscle is also termed voluntary striated muscles. The name " striated" comes from the characteristic cross striations of the muscle fibers when viewed under a microscope.

骨骼肌也称为随意横纹肌。当在察时，肌纤维上可见特征性横纹，" 横纹肌" 的名称就来源于此。

It is usually found as a sheath of muscle fibers surrounding a tube-like structure. When viewed from a microscope, there is no striation presented in the muscle, so it is called involuntary nonstriated muscle.

它通常作为围绕管样结构的肌纤维鞘而存在。用察时，肌肉上并不存在横纹，所以它被称为非随意的无横纹肌。

Like skeletal muscle fibers, cardiac muscle cells have striations. Like smooth muscle fibers, each cardiac muscle cell has only one nucleus and its contraction and relaxation are not under conscious control. Therefore, it is also called involuntary striated muscle.

像骨骼肌纤维一样，心肌细胞也有条纹。像平滑肌纤维一样，每个心肌细胞只有一个核而且其收缩和舒张不受意识控制。因此，它也被称为非随意横纹肌。