Latin: mus - mouse
Histologically, three different muscular tissues can be distinguished which can be subdivided by their most striking microscopical aspects into two more classes.
The striated muscle tissue shows while observing it via microscope fine, characteristical striae which are responsible for the name of the muscle. There are two different types of muscles which are included in the class of the striated muscle.
The muscles of the skin can be distinguished as another type of striated muscle tissue, which however gets included in the group of skeletal muscles by the most authors.
The smooth muscle does not possess any striae and thus is described as smooth. Furthermore, it is not arbitrarily controllable but innervated and controled by the autonomic nerval system. Examples are vascular muscles or muscles of the gastrointestinal tract.
Movement is generated by the exertion of force onto the macroscopical or histological structures, in which the muscles insert. Muscles can only contract themselves activly by spending energy and relax passively. Contraction and relaxation are caused by forwarded electrical signals (action potential). The force of one muscle can be calculated by its physiological cross section. Referring to a parallel aligned muscle it corresponds to the anatomical cross section.
The musculature consists basically of 4 various protein components:
The force of a muscle is directly proportional to its calibre or diameter. However, it is important to regard that a small muscle with a rather small diameter nevertheless can produce a relatively high amount of force, depending of its intramuscular coordination. The force of the muscular body in total is however first of all determined by biomechanical principes, for example the lever principle.
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