Why do muscle work in pars?

Answer 1

All muscles work in pairs to provide movement and stability to the areas they affect. The pairs are located opposite to one another. For example, there are muscles in the front of the shoulders that bring them closer toward the center of the body. You might feel the effect of this when you have been hunched over your computer

for many hours. There are also muscles on the back of the shoulder that open the shoulders away from one another, often providing a goodstrech

.