AOIS posterior muscles acting on shoulder and arm

Trapezius origin

Occipital protuberance, nuchal ligament, spinous process of C7-T12

Trapezius insertion

Clavicle, acromion process, spine of scapula

Trapezius action

Extends and abducts head, rotates and adducts scapula, fixes scapula

Latissimus dorsi Origin

T7-12, L1-5, Sacrum, Iliac crest, ribs 10-12

Latissimus dorsi Insertion

Inter-tubercular groove of humerus

Latissimus dorsi Action

Extends, adducts, and medially rotates arm; depresses shoulder

deltoid origin

clavicle, acromion process, spine of scapula

deltoid insertion

Deltoid tuberosity of humerus (Insertion)

deltoid action

abducts flexes and extends arm, medially and laterally rotates arm

Rhomboideus Major origin

spines of T1-T4

Rhomboideus Major insertion

Inferior medial border of scapula

Rhomboideus Major action

adducts scapula

Rhomboideus minor origin

nuchal ligament, spines of C6- C7

Rhomboideus minor insertion

medial border of scapula at scapular spine

Rhomboideus minor action

Adducts scapula

Levator Scapulae Origin

C1-4

Levator scapulae insertion

Superior angle of scapula

Lavator scapulae action

elevates scapula, abducts and rotates neck

supraspinatus origin

supraspinous fossa

supraspinatus insertion

greater tubercle of humerus

supraspinatus action

abducts arm (stabilizes shoulder joint)

infraspinatus origin

infraspinous fossa

infraspinatus insertion

greater tubercle of humerus

infraspinatus action

extends and laterally rotates arm (stabilizes shoulder joint)

subscapularis origin

subscapular fossa

subscapularis insertion

lesser tubercle of humerus

subscapularis action

extends and medially rotates arm (stabilizes shoulder joint)

teres minor origin

lateral border of scapula

teres minor insertion

greater tubercle of humerus

teres minor action

extends laterally rotates and adducts arm (stabilizes joint shoulder)

teres major origin

lateral border of scapula

teres major insertion

crest of lesser tubercle of humerus

teres major action

extends, adducts, and medially rotates arm

triceps brachii origin

infraglenoid tubercle of scapula, lateral and posterior surface of humerus

triceps brachii insertion

olecranon process of ulna

triceps brachii action

extends, adducts, and medially rotates arm