Most of them are caused by puncture wounds on the palmar transverse lines of the fingers, while hematogenous infections are less common. The sheath is rich in synovial fluid, moist and less bloody, which provides favorable conditions for infection. Once infection occurs, the inflammation quickly spreads to the entire sheath. The sheath infection of the thumb and little finger can also spread to the radial or ulnar bursa and may affect the forearm. In the narrow cavity of the fiber sheath, the inflammation itself and the tension of the exudate can destroy the blood circulation of the tendon, leading to tendon necrosis. Even if the tendon does not necrotize, adhesions often occur after the inflammation heals, seriously affecting the function of the finger.