Pectoralis Major

This course describes the anatomy and integrated function of the pectoralis major muscle (a.k.a. the pec major, and is included in the terms pecs, pectoralis muscle, chest muscles, and pectoral muscles). This muscle has a large, superficial muscle belly on the anterior surface of the chest wall, spanning from the sternum to the anterior deltoid, superficial to the pectoralis minor. This muscle is one of the few muscles that have a significantly larger percentage of type II muscle fibers, when compared to type I muscle fibers. The pectoralis major muscle can be divided into two distinct muscle bellies; the clavicular head originates on the clavicle, and the sternal head originates on the sternum and cartilage of the first six or seven ribs. Both heads invest in a common tendon that inserts into the intertubercle groove of the humerus (upper arm), deep to the anterior deltoid muscle.

The pectoralis major muscle crosses the shoulder joint (glenohumeral joint), is the primary shoulder horizontal adductor, contributes to adduction and internal rotation, the clavicular head contributes to shoulder flexion, and the sternal head contributes to shoulder extension. This course also describes the role of the pectoralis major muscle in glenohumeral arthrokinematics, fascial integration, postural dysfunction, subsystem integration, and synergistic function. For example, the pectoralis major and anterior deltoid contribute to upper limb horizontal adduction and internal rotation, in synergy with the anterior oblique subsystem which aids in rotating the kinetic chain inward, during a wood chop exercise .

Sports medicine professionals (personal trainers, fitness instructors, physical therapists, massage therapists, chiropractors, occupational therapists, athletic trainers, etc.) must be aware of the integrated function of the pectoralis major for the detailed analysis of human movement, and the development of sophisticated exercise programs and therapeutic (rehabilitation) interventions. Further, this course is essential knowledge for future courses discussing human movement analysis, human performance, injury prevention, and physical rehabilitation. For example, the pectoralis major contributes to internal rotation of the upper arm bone in synergy with the anterior deltoid and subscapularis muscles, and the sternal head of the pectoralis muscle contributes to shoulder extension in synergy with the posterior deltoid and latissimus dorsi. Understanding the function of this muscle will aid in the selection of pectoralis major exercises and techniques for enhancing sports performance, especially pushing movements (e.g. hypertrophy and bodybuilding training, pushing a defender out of position, throwing a punch, etc.). And, the pectoralis muscle's role in rehabilitation protocols, including addressing a “tight pec major”, pectoralis muscle tears including complete tears and partial tears, muscle bell tears, pectoralis tendon tears, tendon ruptures, post pectoralis tendon repair, rupture repair surgery, contribution to shoulder joint pain, and shoulder impingement syndrome, etc.

Additional Courses and Techniques:

• Strength Training: Chest Exercises and Pushing Exercise Progressions
• Stretch: Pectoralis Major and Minor Static Stretch (Crucifixion Stretch)
• Vibration: Pectoralis Major and Minor Vibration Release
• Manual: Static Manual Release of the Pectoralis Major

Caption: Dissection of the pectoralis major muscle