ORIGIN: spinous processes of C7 & T1. INSERTION: medial border of the scapula. ACTION: Rhomboid minor and Rhomboid major are working together as a whole to perform the movement. retract scapula (squaring shoulders), synergist with middle fibers of Trapezius. rotate glenoid cavity downward (lowering arm against resistance). stabilize scapula. NERVE SUPPLY: Dorsal scapular nerve