Definition of extensor in US English:

extensor

(also extensor muscle)

noun

Anatomy
  • A muscle whose contraction extends or straightens a limb or other part of the body.

    Often contrasted with flexor
    • ‘To offset well-established volume/area relationships limiting muscle force, larger animals walk on extended limbs and show allometric increases in extensor muscle lever arm lengths.’
    • ‘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.’
    • ‘Then, when you've completed the movement, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint.’
    • ‘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.’
    • ‘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.’

Origin

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

Pronunciation