Pectoralis Major - Anatomy

Origin	Clavicular head: anterior surface of medial half of clavicle; Sternocostal head: anterior surface of sternum, superior six costal cartilages, and aponeurosis of external oblique muscle
Insertion	Lateral lip of intertubercular groove of humerus
Action	Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly; Acting alone: clavicular head flexes humerus and sternocostal head extends it
Innervation	Lateral and medial pectoral nerves; clavicular head (C5 and C6, sternocostal head (C7, C8, and T1) (C5, C6, C7, C8, T1)
Arterial Supply	pectoral branch of the thoracoacromial trunk