Definition of extensor in English:

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Pronunciation: /ikˈstensər/ /ikˈstensôr/
(also extensor muscle)


1A 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.
1.1Any of a number of specific muscles in the arm, hand, leg, and foot.
Example sentences
  • The evolution of the modern name for the special extensor muscle of the index finger is provided by Cauldwell, et al. as follows: Albinus recognized the extensor muscle and noted it in his Historia musculorum hominis.
  • Further, the number of both synapses and active zones per length terminal is significantly larger for the tonic axon in the leg extensor muscle.
  • The triangular fibrocartilage complex is completed by the ulnar extensor muscle subsheath and the ulnar collateral ligament.


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

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