the rhomboids are muscles located in your upper back. They lie underneath the trapezius muscle. These muscles are responsible for retracting your scapula, or pulling your shoulder blades back. Since poor posture causes the shoulders to round forward, the rhomboids are often strained. When this happens trigger points will form. These points cause deep achy pain to be felt along the shoulder blade. Once trigger points have formed they will not release on there own. A manual release such as trigger point massage is required.