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的部分，其中包含两股更小的质——两种不同的丝称和球。

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就像一根由成束质纤维组成的绳子，最小的链是你的和球丝。