A muscle the contraction of which causes movement at a joint with the consequence that the limb or body assumes a more straight line, or so that the distance between the parts proximal and distal to the joint is increased or extended; the antagonist of a flexor. See muscle. [L. one who stretches, fr. ex-tendo, to stretch out]
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ex·ten·sor ik-'sten(t)-sər, -sȯ(ə)r n a muscle serving to extend a bodily part (as a limb) called also extensor muscle compare FLEXOR
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n.
any muscle that causes the straightening of a limb or other part.
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ex·ten·sor (ek-stenґsor) [L.] 1. causing extension. 2. [TA] any muscle that extends a joint.Medical dictionary. 2011.