A Transverse Groove of Greater Sigmoid Notch Guiding Ridge F UNCTIONAL ANATOMY OF THE ELBOW I 20 I

The humeroulnar joint is a uniaxial, diarthrodial modified hinge joint. Motion ranges from 0° to 150° and occurs through a rotational axis in the center of the trochlea, in the coronal plane. At the extremes of flexion and extension, limited degrees of internal and external rotation are present (1). The distal humerus has two components-the trochlea medially and the capitellum laterally. Diagrams show the distal humerus anterior (Fig. 2A), posterior (Fig. 2B), and axial (Fig. 2C) planes. The trochlea is spool-shaped and is covered with articular cartilage from the edge of the olecranon fossa posteriorly to the coronoid fossa anteriorly, a surface area covering approximately 300° to 330° (2). The