Without these we would not be able to bend our arms or legs.

Muscles can pull bones, but they can't push them back to the original position. So they work in pairs of flexors and extensors. The flexor contracts to bend a limb at a joint. Then, when the movement is completed, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint.

Explanation:

not sure if this helps but yea

i have no idea oh hey