Rhomboid Major Muscle

Rhomboid major

ORIGIN:

spinous processes of T2-T5.

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.