Muscles that move the humerus

O=clavicle, sternum, cartilages of ribs 1-6, and aponeurosis of external oblique
I=greater tubercle of humerus
A=prime mover of arm flexion
N=lat. & med. pectoral nerves

O=spines of lower 6 thoracic & vert., lumabar vert, crests of sacrum & ilium, lower 4 ribs
I=intertubercular sulcus of humerus
A=prime mover of arm extension; adducts & rotates arm medially; draws arm downward & backward; important in the power stroke
N=thoracodorsal

O=acromial extremity of clavicle & acromion & spine of scapula
I=deltoid tuberosity of humerus
A=ant-flexes & medially rotates humerus; middle-chief abductor of humerus; post-extends & laterally rotates humerus
N=axillary nerve (C5-C6

O=subscapular fossa of scapula
I=lesser tubercle of humerus
A=chief medial rotator of humerus; stabilizes shoulder joint
N=subscapular nerve (C5-C7)

O=supraspinatus fossa of scapula
I=sup. part of greater tubercle of humerus
A=stabilizes shoulder joint; assists deltoid in abducting arm
N=suprascapular nerve

O=infraspinatus fossa of scapula
I=greater tubercle of humerus
A=rotates arm laterally; adducts arm
N=suprascapular nerve

O=lat. border of dorsal scapular surface
I=greater tubercle of humerus
A=rotates arm laterally; extends and adducts arm
N=axillary nerve

O=post. surface of scapula at inf. angle
I=intertubercle sulcus of humerus
A=extends, medially rotates, and adducts humerus; synergist of latissimus dorsi
N=lower supscapular nerve

O=coracoid process of scapula
I=medial surface of humerus shaft
A=flexes & adducts arm; synergist of pectoralis major; prevents shoulder dislocations
N=musculocutaneous nerve