What is a muscle?

Muscle - is the body tissue which, because it has the power of contraction, enables the higher animals to move their bodies. Muscles are divided into two great groups, voluntary and involuntary, the former being controlled by the will, while the latter act independently. Most voluntary muscles are attached to the skeleton and range in size and shape to suit the particular jobs they perform. They can get into action within a few hundredths of a second, exert an enormous pull on the bone to which they are attached and, if necessary, support 1,000 times their own weight. Involuntary muscles include heart muscle and the muscles of the digestive system, and the fibres of which they are composed are very much smaller than those of voluntary muscle. Because of its exceptionally rich blood supply, muscle is the most infection-free of the body's basic tissues. If it is over-taxed it tires and will stop contracting altogether, but if used normally will give little trouble. 

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