The deltoid is the muscle that covers the tip of the shoulder. It contributes to pain in the shoulder and upper arm. One indication of problems with the deltoid muscle is pain is most intense during activity and subsides when resting the shoulder and arm.
The subscapularis muscle is found on the inside of the shoulder blade. It can cause severe pain in the shoulder blade area that can also run down the back of the arm. Pain is also often felt in the wrist, but not the forearm.
The infraspinatus muscle lines the back of the shoulder blade. It is one of the muscles that can contribute to frozen shoulder. The muscle can cause pain in the shoulder, neck, pain down the outside of the arm which descends down into the thumb and hand. Shoulder mobility can be greatly reduced.
The teres major is a shoulder muscle. It can contribute to pain in the shoulder, upper arm, and forearm. An indication of teres major muscle involvement is pain is felt in the shoulder and upper arm skipping the elbow and reoccurring in the back of the forearm.
The serratus posterior superior muscle is a muscle found in the upper back. It contributes to pain in shoulder, shoulder blade region, arm, hand and little finger. It can also contribute to pain in the upper chest.
The pectoralis minor muscle contributes to pain in the chest, shoulder, arm, hand and fingers. Chest pain can be tenderness or sharp, burning stabbing pain. The pec minor can also contribute to pain in the upper back between the shoulder blades.