The antagonist muscles of the pectoralis minor, a muscle that runs across the front of the chest, include the trapezius, rhomboid major and minor, and the levator scapulae, states Wellness Digest. The pectoralis minor protracts the scapula, or moves it away from the spine.
The antagonist muscles to this action are the middle fibers of the trapezius and the rhomboid major and minor.
The pectoralis minor also depresses the scapula, or shoulder blade, states the American Council on Exercise. This is seen when people lower their shoulder blades. The antagonist muscles to this action are the levator scapulae and the trapezius.
A minor function of the pectoralis minor is the downward rotation of the scapula when the arms are lowered. The antagonist muscles of this action are the trapezius and the lower fibers of the serratus anterior.