s a unit, the four joints of the elbow provide increased mobility for the hand and wrist. ,This unit also provides stalilitv t o lie proximal upper extremity to allow for skilled o r forceful movements of the hand. These functions are reflected in the elbow's unique anatomy and structure. ARTHROLOGY OF THE ELBOW COMPLEXT h e elbow joint complex, illustrated in Figure 1, is composed of the humeroulnar, radioulnar, and superior and inferior radioulnar articulations. T h e superior and inferior radioulnar joints function essentially as one joint, although only the superior radioulnar joint has a direct association with other elbow coniplex counterparts. T h e elbow proper and the superior radioulnar joint are enclosed by a single joint capsule. Humeroulnar JointT h e humeroulnar joint is a uniaxial, diarthrodial joint, with 1 degree of freedom, flexion, and extension. Although generally described as a hinge joint, the humeroulnar joint is probably more appropriatelv designated a modified hinge joint, with small amounts (approximately 5") of internal and external rotation occurring at the extremes of flexion and extension (26). This joint's rota- Anatomy of the Elbow