Arm pain is generally caused by a problem in the neck such as a disc herniation or pinched nerve. Shoulder and elbow problems can cause referred pain to the arm. Many of these conditions are covered on the neck, shoulder, and elbow pages. Of course, muscles and joints of the arm can be sources of pain (see Muscle & Joint Pain page) and another source of arm pain may include:
Thoracic outlet syndrome – This is an umbrella term that encompasses three related syndromes that involve compression of the nerves, arteries, and veins in the “thoracic outlet.” The thoracic outlet is the space between your collarbone and your first rib. Tightness in this narrow region of the body can lead to compression of the nerves (brachial plexus) or blood vessels (subclavian artery and vein) that pass through. Compression of these structures leads to lower neck, upper chest, and arm pain as well as tingling, numbness, weakness or blood flow changes in the extremity. The most common cause of tightness in this region involves tightness of the scalene muscles in the neck and/or pectoral muscles in the chest. This generally leads to compression of the brachial plexus – the bundle of nerves located here. More rare causes of tightness include swelling of the blood vessels or presence of an extra rib. Approximately 1 in 500 people have a cervical rib, a congenital abnormality where an extra rib extends from the 7th vertebrae of the neck.