Anatomy of the joints of the thumb

The three joints of the thumb differ markedly with respect to anatomy and function. Each contributes its own anatomic personality, and when functioning together, they allow the thumb to move with remarkable versatility and grace yet with the stability necessary to perform a wide variety of tasks. The carpometacarpal and interphalangeal joints allow for thumb mobility while the metacarpophalangeal joint provides stability. Thumb rotation primarily takes place at the CMC joint, although the MP and IP joints each contribute a small amount of pronation with flexion. Although much is known about the static structural anatomy of the thumb, its dynamic anatomy requires further investigation. The fluid, elegant and powerful movements of the thumb are complex, and defining the contributions of the various individual structures is difficult. Hopefully, future investigators using newer techniques will unravel the complexities of the functional anatomy of this remarkable digit.