muscle
The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.
DEFINITION:
- muscle
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An organ which by contraction produces the movements of an animal organism. Muscles are of two varieties: striated , or striped , including all the muscles in which contraction is voluntary and the heart muscle; unstriated , nonstriated , smooth , or organic , including all the involuntary muscles except the heart, such as the muscular layer of the intestines, bladder, blood vessels, etc.
striated muscles - Striated muscles are covered with a thin layer of connective tissue ( epimysium ) from which septa ( perimysium ) pass, dividing the muscle into bundles of fibers, or fasciculi . Each fasciculus contains a number of parallel fibers separated by connective tissue septa ( endomysium ). Each fiber consists of sarcoplasm which is cross-striated or composed of alternate light and dark portions (whence the name striated muscle ); each contains embedded in it the myofibrils and each is surrounded by sarcolemma .
nonstriated muscles - A type of muscle without transverse striations in its constituent fibers; such muscles are almost always involuntary. Called also smooth muscle (See below).
smooth muscles - Smooth muscles are composed of elongated, spindle-shaped, nucleated cells arranged parallel to one another and to the long axis of the muscle, and these cells are often grouped into bundles of varying size. The muscles, bundles, and cells are enclosed in an indifferent connective tissue material much as is found in striated muscles.
Used in 3 Article abstracts
Used in 3 Article abstracts