[Applied anatomic observation on the synovial membrane of the digital sheath]

The synovial membrane of various parts of flexor tendons and sheaths was examined with the aid of light and scanning electron microscopes. The results show that on the compressed sites such as the volar aspect of the tendon and the inner aspect of the pulley, no continuous synovial cell layer and blood vessel existed, indicating that these areas may not closely related to the secretion of synovial fluid. Alternatively, on the areas of lesser burden such as the reflexion of the synovial capsule, the short vincula and the small cul-de-sacs at either end of each pulley, the synovial membrane became thicker and the number of synovial cells greatly increased, and there were exuberant capillary networks underneath the synovial membrane. All these add up to a concept that these areas are closely associated with the secretion of synovial fluid, and should certainly be preserved during operation.