The biceps brachii muscle is found in the front of the upper arm. It contributes to pain in the shoulder, upper arm and elbow. Straightening the arm when the palm is facing up can be painful and difficult.
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 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 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 supraspinatus muscle is one of the four rotator cuff muscles. It contributes to pain in the shoulder, outside of the arm and elbow. Pain is a deep aching that often persists during rest.
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 teres minor connects the shoulder blade to the upper arm and is one of the rotator cuff muscles.
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.