Painful straightening of the right middle finger may be caused by stenosing tenosynovitis, arthritis, insufficient blood supply, or arterial system diseases, etc., and the cause of the pain should be identified in a timely manner. 1. Stenosing tenosynovitis: It may be caused by stenosing tenosynovitis or localized tenosynovial cysts, which can be touched by hard knots and lumps, and accompanied by pain when straightening. 2. Arthritis: For example, rheumatoid arthritis, which is more obvious in the morning after waking up, will be manifested by pain in the middle finger of the right hand. In addition, osteoarthritis can also lead to pain in the middle finger of the right hand, which is mostly caused by chronic strain, degeneration of articular cartilage or the formation of bone spurs, which is manifested as swelling, pain and limited movement of the finger joints. 3. Insufficient blood supply or arterial system diseases: mainly due to insufficient blood supply or arterial system diseases, such as arterial embolism, arteritis, etc., there will also be obvious numbness, and even body checking will also find that the skin temperature is lowered or there is a warm band. Therefore, if the symptoms of straightening pain in the middle finger of the right hand are not relieved within a short period of time, it is necessary to go to the regular hospital in time to improve the relevant examination and choose a reasonable treatment method.