In the body, a pair of muscles
working together to allow coordinated movement of the skeletal joints. Muscles can only exert a force and do work by contracting. An example is the antagonistic pair of muscles used in bending and straightening the arm. To bend the arm requires one set of muscles the biceps
to contract, while another set the triceps
relaxes. If the arm is to be straightened, the reverse happens. The individual components of antagonistic pairs can be classified into extensors (muscles that straighten a limb) and flexors (muscles that bend a limb).
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