THE DOUBLE SHEATH SYSTEM AND TENDON GLIDING IN ZONE 2C

Anatomical structures, the morphology of gliding tunnel, the gliding a mplitude of tendons and the range of finger motion after sheath incisi on in zone 2C were studied in 40 fingers of ten preserved cadaver hand s, The tendon of FDS in zone 2C courses around that of FDP, and FDS se rves functionally as a second sheath for FDP, This ''double sheath'' s ystem in zone 2C accounts for the poor results of tendon repair in zon e 2C, The tendon repairs in zone 2C glide into zone 2D during finger f lexion, Therefore, the condition of the gliding tunnel of zone 2D is a lso important to the function of tendon repairs in zone 2C, The range of motion was shown to be insignificantly influenced by partial incisi on of the A2 pulley, and this did not decrease the total strength of t he sheath markedly, These suggest that partial incision or enlargement of the A2 pulley can be carried out for tendon repairs in zone 2C wit hout causing mechanical problems of function.