Thousands of tiny, parallel threads called myofibrils squish together to form muscle fibers, which are your actual muscle cells — cells with mitochondria, multiple nuclei, and a cellular membrane called a sarcolemma.

数以千计被称为肌原纤维的微小平行线挤压在一起形成肌肉纤维，这就是你真正的肌肉细胞——具有线粒体、多个细胞核和称为肌膜的细胞膜的细胞。