An extensor is a muscle that increases the angle between bones or body parts at a joint, effectively straightening or extending that part of the body. For example, extensors straighten the elbow or knee, or bend the wrist or spine backward

. These muscles oppose flexors, which decrease the angle by bending joints. In humans, extensors are found in various parts of the body, including the arms, hands, legs, and feet. Specific examples include:

• In the forearm and hand: extensor carpi radialis brevis and longus, extensor carpi ulnaris (extend the wrist), extensor digitorum (extends the fingers), extensor indicis (extends the index finger), and extensor pollicis brevis and longus (extend the thumb)

• In the lower limb: extensor digitorum longus and brevis (extend the toes), extensor hallucis brevis and longus (extend the great toe)

Extensors work by pulling on tendons that cross joints, causing the joint angle to increase and the limb or digit to straighten

. This action is essential for movements like straightening the arm or leg, lifting the back of the hand, or extending fingers and toes. In summary, an extensor is a muscle responsible for extending or straightening parts of the body by increasing the angle at a joint