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extensor Line breaks: ex¦ten|sor
Pronunciation: /ɪkˈstɛnsə/
(also extensor muscle)

Definition of extensor in English:


A muscle whose contraction extends or straightens a limb or other part of the body. Often contrasted with flexor.
Example sentences
  • The limb is supplied with a single extensor muscle and a single flexor, all other joints are considered rigid, and the objective of the CNS is to maintain the position of the limb.
  • The anterior compartment flexor muscles of the arm are innervated by the musculocutaneous nerve, and the large posterior compartment extensor muscle is innervated by the radial nerve.
  • Flexion force applied against long finger (third digit) extension distal to the proximal interphalangeal joint may provoke pain over the extensor muscle mass in the proximal forearm.


Early 18th century: from late Latin, from extens- 'stretched out', from the verb extendere (see extend).

Definition of extensor in:
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