Groups of muscles work together, for example when the biceps muscle contracts to flex (bend) the forearm, the triceps muscle relaxes. To extend (straighten) the forearm the biceps relaxes and the triceps contracts.
Groups of muscles work together, for example when the biceps muscle contracts to flex (bend) the forearm, the triceps muscle relaxes. To extend (straighten) the forearm the biceps relaxes and the triceps contracts.