Pectoralis Major

The Pectoralis major is a muscle of the chest.

Collectively with the Pectoralis Minor, they maybe referred to as the Pecs.

Anatomical Attachments:

• Origin: Attaches to the clavicle, sternum, costochondral junction of the 2nd to 7th ribs, as well as the superficial aponeurosis of the external oblique.
• Insertion: Attaches to the crest of the greater tubercle of the humerus.

Action: Adducts the arm, pulls it forward and rotates it internally.

Synergist: Pectoralis minor, Subclavius, Serratus anterior, Trapezius, Latissimus dorsi, Rhomboid major and minor, Levator scapulae.

Antagonist: Deltoid, Supraspinatus, Infraspinatus, Teres major and minor, Subscapularis.

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Nerve Supply: Medial and lateral Pectoral nerve (C5, C6, C7, C8, and T1).

Vascular supply: Pectoral branch of the thoracoacromial and the perforating branches of the interior thoracic artery.

Vascular entrapment: While there are no studies depicting neurovascular entrapment by the pectoralis major, Travell and Simon’s state that entrapment of the axillary lymph nodes will result in breast swelling and tenderness.

• Primary: The pain refers to the anterior chest and breast, and may extend down the arm to the fingers.
• Satellite or associated triggers: Latissimus dorsi, Teres major, Subscapularis, Serratus anterior, Coracobrachialis, Rhomboids, Middle trapezius, Infraspinatus, Teres minor, posterior Deltoid.

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Trigger Point Signs and Symptoms: Chest pain; front of shoulder pain; restricted shoulder abduction; subclavicular, arm, breast pain and tenderness.

Trigger Point Activating and Perpetuating Factors: Round shoulder posture, prolonged sitting while riding, slouched posture, heavy lifting, anxiety, sudden cooling of muscle.

Differential Diagnosis: Angina pectoris, Bicipital tendonitis, Costochondritis, Supraspinatus tendonitis, Subacromial Bursitis, Medial epicondylitis, Lateral epicondylitis, Pleurisy, (Segmental, Subluxation, Somatic dysfunction) C5 C6 C7 C8 or T1 Radiculopathy, Intercostal neuritis, Lung cancer, Mastitis, Breast cancer, Menses, Fibrocystic Breast disease, Lymphatic cancer, Lymphedema, Lymphadenopathy, Myocardial infarction, Esophagitis, Gastroenteritis, Hiatal Hernia, Gallbladder Dysfunction, Polyneuropathy, Polymyalgia rheumatica, Fibromyalgia, Polymyositis, Systemic lupus erythematosus, Ankylosing spondylosis, Diabetic neuropathy, Osteoarthritis, Osteoporosis, Eosinophilic fasciitis, Tetanus, Systemic infections or inflammation, Nutritional inadequacy, Metabolic imbalance, Toxicity, Side effects of medication.

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