1. Stenosing tenosynovitis: It mostly occurs in the tendon sheaths of the extensor hallucis longus and extensor hallucis longus muscles, which is called stenosing tenosynovitis of the radial tuberosity, and it occurs in the flexor tendons of the thumb or fingers, which is called “trigger finger”. Although the synovial membrane of the tendon sheath secretes synovial fluid to lubricate the tendon sheath, repetitive friction is unavoidable with certain specialized movements, such as carpentry, weight lifting, restaurant servers, and manual operators. Since the tendon sheaths mentioned above act as a carriage, the friction is the greatest and most likely to be damaged, manifesting as thickening of the tendon sheaths, which affects the normal movement of the tendons. Stenosing tenosynovitis may also be the result of certain static or subclinical collagen diseases. 2, acute fibrous tenosynovitis: also known as friction tone synovitis. The site of the lesion is in the connective tissue surrounding the synovium, where edema, congestion, and leukocyte and plasma cell infiltration are seen. The disease is characterized by a soft friction sound, which is caused by the protofibers of the connective tissue rubbing around the edematous tendon. The most common site is the upper part of the wrist, characterized by the radial wrist extensor digitorum longus tendon and the muscle belly of the bunion longus, bunion shortus extensorum is most likely to produce, also known as twisting pronation tenosynovitis. 3, acute plasma tenosynovitis: also called rheumatic tenosynovitis, is part of the systemic rheumatism, for acute rheumatic fever a reaction. Patients have high fever, joint pain, swelling, effusion, of which the most important lesion is rheumatic myocarditis. After the fever subsides, the plasma exudation from the tendon sheath is absorbed, and the tenosynovitis is cured. 4, acute septic tenosynovitis: often occurs after trauma, especially puncture wounds, mostly in the flexor tendons of the wrist and fingers. The early stage of infection is synovitis of the tendon sheath, then the tendon loses its luster, turns gray or green, and at the same time is infiltrated with pus and necrosis. The most common is staphylococcus, followed by streptococcus. 5.Tuberculous tenosynovitis: caused by Mycobacterium tuberculosis infection. It first invades the synovial membrane of tendon sheath, and spreads upward from the palm to the forearm along the ulnar and radial bursa through the carpal tunnel. The tendon sheath is hypertrophied due to the infiltration of tuberculous granulomatous tissue, and the sheath contains yellow exudate and yellow granulomas. Gradually, the tendon is also infiltrated by granulation tissue and forms nodular hypertrophy, losing its original smoothness and motility. When the granulation tissue invades other tendon sheaths and nerves, it may cause flexion and sensory deficits.