The muscle below the thumb mainly refers to the intertrochanteric, pressing the common causes of soreness are overwork, stenosing tenosynovitis, tenosynovial cysts and so on. 1. Overexertion: when the movement is not appropriate or long time to maintain a fixed position, can lead to interphalangeal muscle group strain and soreness and muscle stiffness, tension and other symptoms, at this time, it is recommended to take appropriate rest, can be through the massage of hot compresses to assist in relieving. 2. Stenosing tenosynovitis: commonly known as stenosing tenosynovitis of the flexor tendon, prolonged mechanical friction can lead to tissue hyperplasia and hypertrophy within the tendon sheath, narrowing of the tendon sheath, tendon sheath and flexor tendon can be edematous, resulting in pain and soreness when pressed on the pisiform muscle group, and in severe cases, symptoms of limited activity can occur. 3. Tendon sheath cysts: These are benign swellings near the tendon of the flexor digitorum longus, mostly caused by excessive friction of the tendon or tendon sheath as a result of prolonged repetitive strain injury. When the cyst compresses the nerves, it can cause soreness and numbness of the fingertips and other pathological manifestations. If the blood vessels are compressed, symptoms such as coldness or pallor of the fingertips may occur. In addition to the above common causes, less common are osteochondroma of the hand, hemangioblastoma, and trauma. When symptoms of muscle pressure soreness below the thumb appear, it is recommended to seek medical treatment in time to avoid delaying the condition.