structure of the sarcomere the contractile unit of skeletal muscles. myosin and actin filaments, discs, z-line, myosin heads, m-li

actin anatomical anatomy are band biology contract contracted contractile contraction disc discs drawing education fiber fibre filament filaments heads health human illustration labeled layer line lines mechanism medical medicine muscle muscles musculoskeletal myofibril myofilaments myosin physical physiology relaxed sarcolemma sarcomere sarcomeres science skeletal striated striation structure thin this tropomyosin troponin unit vector zone