There are several reasons for the pain in the arm external meridian: 1, tenosynovitis tenosynovitis is one of the common causes of each arm carpal tendon pain is one of the important reasons, it is a sharp pain, and activities aggravated, slightly reduced after rest, the pain lasts for a poor time, most of which need to be treated. 2, it may be caused by rheumatic diseases such as rheumatism, rheumatoid rheumatism, ankylosing spondylitis and so on, and the pain tends to be symmetric localized redness, swelling, heat and pain. Blood sedimentation is relatively fast, the corresponding characteristic examination is positive. 3, may be caused by trauma, trauma may cause localized swelling and pain. In addition to this, it should also be clarified, is there herpes virus caused by nerve damage and carpal tunnel syndrome, elbow tube syndrome, cervical spondylosis, bone tumors, these diseases can also cause localized pain, so the cause of arm carpal tendon pain depends on different situations.