Muscle: Pectoralis major

Proximal Attachment:

• Clavicular head - Anterior surface of medial half of clavicle

• Sternocostal head - Anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle

Distal Attachment: Lateral lip of intertubercular sulcus of humerus

Innervation: Lateral and medial pectoral nerves

                         - Clavicular head (C₅, C₆)

                         - Sternocostal head (C₇, C₈, T₁)

Main Action(s):

• Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly

• Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position