Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia or epimysium.
Each muscle bundle or fascicle is surrounded by a perimysium.
Each muscle bundle or fascicle contains a number of muscle fibres or myofibers. These are the muscle cells.
The myofibres are covered with endomysium.
Each myofiber is lined by the plasma membrane called sarcolemma enclosing the sarcoplasm.
The muscle fibre is a syncytium as the sarcoplasm contains many nuclei.
The endoplasmic reticulum, i.e., the sarcoplasmic reticulum of muscle fibres is the storehouse of calcium ions.
A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils
Each myofibril has alternate dark and light bands on it
A detailed study of the myofibril has established that the striated appearance is due to the distribution pattern of two important proteins – Actin and Myosin
The light bands contain actin and are called I-band or Isotropic bands, whereas the dark band called ‘A’ or Anisotropic band contains myosin
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Structure of Skeletal Muscle
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