anatomy of a skeletal muscle fiber. myofibril structure

muscle anatomy skeletal structure fiber myofibril myosin zline mline actin filaments sarcomere contractile proteins zdisc hzone theory contraction unit junction tension function fibril sarcostyle organelle tendons bone skeleton isometric flat vector myofilaments striated muscular cell health medical science tissue diagram contract line thick atp sarcolemma healthy contracted labeled fibre template education scientific relaxation