Anatomy of the flexor tendon sheath and pulley system: a current review.

The flexor tendon sheath in the fingers is a synovial-lined, fibroosseous tunnel with segmental condensations of fibrous tissue. These fibrous bands or pulleys are: (1) the palmar aponeurosis pulley (formed by the transverse fibers of the palmar aponeurosis), (2) five annular pulleys, and (3) three cruciform pulleys. The second and fourth annular pulleys are the largest, thickest, and most constant in form and incidence. The first, third, and fifth annular pulleys are less constant in shape and incidence as are the cruciform pulleys. No other pulleys have been identified in this study.