Military forces have worn distinctive uniform items for centuries to create a psychological advantage and boost their esprit de corps, but the military use of berets is a relatively recent phenomenon. In the 16th and 17th centuries, the Blue Bonnet became a de facto symbol of Scottish Jacobite forces.
Muscle cells have adapted to their job by contracting and relaxing.  When calcium levels are increased the muscle cells contract. On the  other hand, when calcium levels droâ¦p the muscle cells get relaxed.
Quick Answer. The two main functions of a muscle cell are to produce movement through force and to maintain posture, according to Science360. They are frequently called muscle fibers because the length of a muscle cell is greater than the width. Continue Reading.