The Pecs attach to the humerus near the shoulder joint and originate on the breastbone in the center of the chest.
The fibers of the Pectoralis muscles run like a fan across the chest. The fan-like structure of the Pecs allows the humerus to move in a variety of planes across the body.
The Pectoralis Minor muscle is located underneath the pectoralis major muscle, attaching to the coracoid process of the scapula and originating on the middle ribs.
The function of the Pectoralis Major is to bring the humerus across the chest. A flye movement is the best example of this action.
The Pectoralis Minor serves to move the shoulder area forward. This can be seen by shrugging your shoulder forward.