where are there muscles in a woman's breast?
Your breasts are made up of two major muscles â the Pectoralis Major and Pectoralis Minor as well as many smaller muscles. These muscles lie underneath the breast tissue and on the breastbone, and connect to the humerus (the arm bone closest to your shoulder joint). Your chest plays a major part in helping to bring your arms across your body and your shoulders forward. These exercises target your upper, middle or lower chest muscles and therefore result in a firmer bust. Prev. Next >>.