Henry Gray

Fracture of the patella may be produced by muscular action or by direct violence. When produced by muscular action, it occurs thus: a person in danger of falling forwards attempts to recover himself by throwing the body backwards, and the violent action of the quadriceps extensor upon the patella snaps the bone transversely across.

English Scientist

The term 'extensor' refers to muscles related to the straightening of a body part.

Body Movements

'Extensor' is used in medical or biological contexts, not in everyday language.

Technical Term

An 'extensor' is often specified by the body part it is associated with.

Location Specific

 They don't really have so many of the extensor muscles that are the weight-bearing muscles; instead, they rely on retractor muscles to pull themselves along. They have long, hooked claws and a high fatigue resistance,