the serratus anterior muscle is located on the side of the trunk. It attaches onto the ribs and the scapulae. This muscle assists in scapular motion and stability as well as assisting the movement of the ribs. Trigger points can form in this muscle due to poor shoulder posture. Once formed, these points will cause pain to be felt in the side, under the armpit, and down the inside of the arm. Once formed trigger points will not release on their own, they require a manual technique such as trigger point massage.