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 brachialis muscle connects the upper arm to the lower arm. It contributes to pain in the upper arm, elbow, thumb pad and thumb. It can also cause tingling and / or numbness in the back of the forearm into the thumb. Bending and straightening the elbow is painful.
The coracobrachialis muscle connects the shoulder to the upper arm. It can contribute to pain in the shoulder, back of the arm, and occasionally the middle finger. Pain is often felt when attempting to put your hand behind your back and or raising your arm over your head.
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.