Your lats, or your latissimus dorsi muscles are the largest muscles of the back. They are responsible for adducting and medially rotating the arm. This muscle also produces extension at the shoulder joint. When trigger points for In this muscle, they can refer pain into the back, down the inside of the arm into the hand. These trigger points can also cause pain to be felt into the front of the shoulder. Once formed trigger points will not release on there own. They require a manual release technique like trigger point massage.