Finger pulley system

The retinacular portion of the finger tendon sheath consists of cruciform, annular, and transverse tissues that facilitate smooth gliding of the tendons and form a pulley system that enables effective finger flexion without displacement of the tendons (ie, "bowstringing"). The retinacular pulley system is comprised of the palmar aponeurosis (PA) pulley (not shown), five annular (A) pulleys, and three cruciform (C) pulleys.