The middle trapezius and rhomboid muscles are to blame. This is the first of two releases.
Anatomy of a muscle
The middle section of the trapezius is on the surface of the muscular system. It runs from the spine to the far end of the shoulder blade. The rhomboids are underneath the trapezius and run from the spine to the inner edge of the shoulder blade. These muscles forcefully bring the shoulder blades together and stabilize the shoulder girdle.
Causes of tightness
Bad posture makes these muscles statically contract to protect the ligaments of the spine and the discs. Shortened chest muscles can place demands on these muscles that surpass their capability. To see if you have tight chest muscles, take the pencil test.
Symptoms of Tightness:
Pain and aching between the shoulder blades
Aching toward the front of the shoulder
Numbness between the shoulder blades
Stand with your back against a wall
Take a tennis ball, lacrosse ball or softball and place it between your shoulder blades on one side of your spine
Step away from the wall about 6 to 10 inches or until you feel a pain threshold of between 5 to 8 on a scale of 1 to 10, ten being excruciating. The point here is to cause enough tension on the muscle to release trigger points
Stay on this spot between 30 seconds to 2 minutes or until you feel the muscle release or until there is no pain
If the muscle releases before the 2 minutes is over, find a new spot by moving your body either slightly up or down or in toward your spine or out toward your shoulder blade and hold for the remaining time
To increase the tension on the rhomboid muscle open up the shoulder blade by moving the arm across the body
Enjoy the relief!