Akademik

Smooth muscle

One of the three types of muscle tissue in the body (skeletal, smooth, cardiac). Generally forms the supporting tissue of blood vessels and hollow internal organs such as the stomach, intestine, and bladder. So named because of the absence of microscopic lines called "cross-striations" which are seen in the other two types.

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smooth muscle n muscle tissue that lacks cross striations, that is made up of elongated spindle-shaped cells having a central nucleus, and that is found esp. in vertebrate hollow organs and structures (as the small intestine and bladder) as thin sheets performing functions not subject to direct voluntary control and in all or most of the musculature of invertebrates other than arthropods called also nonstriated muscle, unstriated muscle compare CARDIAC MUSCLE, STRIATED MUSCLE

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(involuntary muscle)

muscle that produces slow long-term contractions of which the individual is unaware. Smooth muscle occurs in hollow organs, such as the stomach, intestine, blood vessels, and bladder. It consists of spindle-shaped cells within a network of connective tissue and is under the control of the autonomic nervous system. Compare striated muscle.

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smooth involuntary muscle a type of muscle without transverse striations in its constituent fibers; it is found in the walls of the viscera and blood vessels and in the dermis and is not under voluntary control. See muscle and see Plate 32.

Medical dictionary. 2011.