They're divided lengthwise into segments called sarcomeres, which contain two even tinier strands of protein — two different kinds of myofilaments called actin and myosin.

它们在纵向上被分成称为肌节的部分，其中包含的白——不同的肌丝称为肌动白和肌球白。

You'd also re-learn that your skeletal muscles are constructed like a rope made of bundles of protein fibers, and that the smallest strands are your actin and myosin myofilaments.

你还会重新了解到你的骨骼肌就像一根由成束白纤维组成的绳子，最的链是你的肌动白和肌球白肌丝。