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Coronoid Process (Ulna)

processus coronoideus ulnae

The coronoid process is the anterior projection of the proximal ulna forming the anterior wall of the trochlear notch, articulating with the humerus and providing the anterior stability of the elbow joint. It is fractured in approximately 15 percent of elbow dislocations as the anterior joint surface is sheared off during posterior elbow dislocation. The coronoid is the keystone of elbow stability — without adequate coronoid height the elbow cannot resist the valgus and posterolateral rotation forces of the reconstructed elbow after dislocation.

Region: Upper Arm

Clinical Relevance

Clinical Notes

The terrible triad of the elbow (posterior dislocation + radial head fracture + coronoid fracture) is the most complex elbow injury, requiring surgical fixation of all three components for stability. The O'Driscoll classification of coronoid fractures guides repair — type I (tip fractures less than 2 mm) can be treated non-operatively, while larger fragments and anteromedial facet fractures require fixation. The anterior bundle of the MCL inserts on the sublime tubercle at the coronoid base.