Origin: medial half of clavicle, lateral margin of sternum, costal cartilidges 1-7, aponeurosis of external oblique

Insertion: lateral lip of intertuberal groove of humerus

Action: flexes, adducts, and medially rotates humerus "hugging muscle"

Origin: vertebrae T7-L5, lower 3-4 ribs, iliac crest, thoracolumbar fascia

Insertion: floor of intertuberlar groove of the humerus

Action: extends, adducts, and medially rotates humerus "handcuff muscle"

Origin: acromion and spine of scapula, clavicle

Insertion: deltoid tuberosity of humerus

Action: flex and medially rotate humerus, abduct humerus, extend and laterally rotate humerus

Origin: Supraspinous fossa of scapula

Insertion: greater tubercle of humerus

Action: abduction of humerus

Origin: infraspinous fossa of scapula

Insertion: greater tubercle of humerus

Action: rotates humerus laterally

Origin: inferior angle of scapula

Insertion: medial lip of intertubercular groove of humerus

Action: extends and medially rotates humerus

Origin: lateral border and adjacent posterior surface of scapula

Insertion: greater tubercle of humerus

Action: rotates humerus laterally

Origin: subscapular fossa of scapula

Insertion: lesser tubercle of humerus

Action: rotates humerus medially

Origin: coracoid process of the scapula

Insertion: medial aspect of humeral shaft

Action: flexes and medially rotates humerus