A muscle that straightens a joint is called an extensor.
extensor
A flexor is a muscle that causes a joint to bend. In contrast, an extension is a muscle that straightens a joint.
A muscle that straightens a limb at a joint is called an extensor. Extensors work by contracting to increase the angle between the bones at a joint, allowing for movement such as straightening the elbow or knee. In contrast, muscles that bend a limb at a joint are known as flexors. Together, these muscle groups enable a wide range of motion in the body's joints.
To extend a muscle A MOTION IS MADE TO INCREASE AN ANGLE BETWEEN TWO BONES.
extends leg; straightens knee joint
An extensor straightens part of your body.
They're referring to opposite motions, if a muscle bends a joint - it's antagonist straightens it out.
a big one
Extender
Extensor
The extension of the lower arm is a result of the contraction of the triceps muscle, which is located on the back of the upper arm. When the triceps contracts, it straightens the arm by extending the elbow joint.
The main extensor of the arm is the triceps brachii muscle. It is located on the back of the upper arm and is responsible for extending the elbow joint, which straightens the arm.