This chapter provides a comprehensive examination of the anatomy and biomechanics of hand pulley systems, emphasizing their role in maintaining tendon function and finger kinematics, as well as implications for surgical repair. The first section reviews the detailed anatomical features of the flexor tendon sheath, including the five annular pulleys, three cruciform pulleys, and the palmar aponeurosis pulley, highlighting variations in pulley morphology across different digits and between the thumb and fingers. It discusses the clinical relevance of anatomical landmarks—such as the variability in A1 pulley confluence and the distinct structure of the A5 pulley—and recent discoveries like the A0 pulley in the thumb. The subsequent section delves into the biomechanics of the pulley system, elucidating how pulleys optimize tendon excursion, moment arm mechanics, and flexion work. It examines factors influencing tendon gliding, including pulley strength, friction, and lubrication mechanisms, and demonstrates the biomechanical consequences of pulley injuries and excisions on joint kinematics, bowstringing, and force transmission. Experimental findings, supported by in vitro studies and cadaveric models, are presented to underscore the critical roles of the A2 and A4 pulleys in preserving finger function and the efficacy of various repair techniques. Together, these insights provide a framework for understanding the interplay between anatomy and biomechanics in the context of hand function and surgical intervention.