Can the biceps brachii function or moves without the synergist muscles brachialis?
You have different types of muscle tissue, the muscle that you mentioned, the biceps brachii is in the upper arm on the front side of the body. It is a skeletal muscle, a voluntary muscle that is attached to a bone. In this case the underlying bone is the humerus. All skeletal muscle action(contraction) is based on three muscles, the prime mover, the antagonist, and the synergist or synergistic muscle. The prime mover is the muscle contracting or the muscle doing most of the work. The antagonist is the muscle that is anatomically most opposite(on the other side of the structure). The antagonist of the biceps brachii is the triceps. When a prime mover contracts, the antagonistic muscle relaxes. A synergistic muscle is the "helping muscle", the muscle that helps the prime mover to contract. The synergistic muscle of the biceps brachii is the brachialis(located on the side-lateral upper arm). When any muscle contracts, all three must be functional. If any of the three are nonfunctional, the prime mover will not work or contract.