At the smaller scale, these skeletal muscle fibers are comprised of millions of sarcomeres— the smallest contracting unit of muscle tissue.

在较小的尺度上，这些骨骼肌纤维由数百万个肌节组成——肌肉组织的最小收缩单位。

Skeletal muscle fibers are both structurally and functionally separate from each other, meaning that some cells can work while others don't — that's why you can grasp a delicate flower with the same hand that you can use crush a soda can.

骨骼肌纤维在结构和功能上都是相互分离的，这意味着有些细胞可以工作，而有些则不行。这就是为什么你可以用捏碎汽水罐的同一只手去抓一朵精致的花。

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。