Muscle tissues

Striated muscle tissues

• They contain certain specialized contractile structures called striated myofibrils consisting of regularly recurring patterns (bands) with different optical properties (birefringence in polarized light)

Skeletal striated muscle tissue

• constitutes skeletal muscles as well as muscle coats in the walls of some digestive system organs (oral cavity, tongue, pharynx, oesophagus, rectum) and vagina
• consists of muscle fibers

A muscle fiber

• comprises the myosyncytium and myosatellite cells
• is surrounded by a sarcolemma (myosyncytial plasma membrane) and a basement membrane
• the myosyncytium contains numerous peripheral nuclei under the sarcolemma and tightly packed striated myofibrils (1-2 thousand) in central parts of the sarcoplasm (each myofibrillar length is equal to the whole muscle fiber length)
• myosatellite cells are cambial cells on the external surface of myosyncytial plasma membrane under the basement membrane
• muscle fiber size differs depending on anatomical features of organs: the diameter is 10-100 μm, the length ranges from several mm to 10-12 cm
• the fibers exhibit a potential for rapid, voluntary, powerful contractions

Skeletal striated muscle tissue

Structure of muscle fiber