The elbow is a trochoginglymus joint with three articulations (the ulnohumeral, radiocapitellar, and proximal radioulnar joints) and two degrees of freedom (flexion/extension and pronation/supination). The congruity of the articulations as well as the medial and lateral collateral ligament complexes account for a majority of the stability of the joint. Muscles play a dynamic role in stabilizing the elbow. Understanding the anatomy and biomechanics of the elbow is essential to diagnosing and treating problems that develop in a patient's elbow.