A sarcomere contains both thin filaments, made up mostly of two light and twisty actin strands, and thick filaments, composed of thicker, lumpy-looking myosin strands.

肌节既包含细丝，主要由两条轻盈而扭曲的肌动蛋白链组成，也包含粗丝，由更厚、看起来块状的肌球蛋白链组成。