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 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 supinator muscle is located on the thumb side of the elbow. It can contribute to pain in the elbow, forearm, and back of the hand at the base of the thumb. It can also contribute to numbness and tingling in the thumb side of the hand.
The brachioradialis is located on the outside of the arm and is a contributor to tennis elbow. It can cause pain on the outside of the elbow, forearm and often descends down into the wrist and thumb. It can contribute to numbness around the thumb as well as a weakened grip.
The subclavius muscle is found just under the collarbone. It contributes to pain in the area around the clavicle (collarbone), shoulder, upper arm, forearm, thumb and fingers. It can also contribute to tingling and numbness in the arm and hand.