Coronoid process of the ulna: paleopathologic and anatomic study with imaging correlation. Emphasis on the anteromedial "facet".

Objective: The purpose of this study was to provide a detailed description of the anatomy of the coronoid process of the ulna and to use magnetic resonance (MR) images and anatomic correlation with cadavers to show the macroscopic configuration of this structure.

Materials And Methods: Photography and high-resolution radiography were performed in 26 ulna specimens from the collection of a local museum. MR imaging of the coronoid process of 11 cadaveric elbows was performed. The images were compared with those seen on anatomic sectioning.

Results: The anteromedial rim of the coronoid process of the ulna had a regular surface, without osseous irregularities or facets in 69.2% of the specimens. In 30.8% of the specimens, the anteromedial rim was not regular and a small ridge could be identified. The insertion site of the joint capsule was onto the anterior aspect of the coronoid process, at an average distance of 5.9 mm distal to the tip. The attachment of the anterior band of the ulnar collateral ligament at the sublime tubercle was flush with the articular margin in 63.6% of the specimens. In 36.4% of the specimens, a more distal attachment, with a separation between the undersurface of the ligament and the adjacent tubercle, was seen. The brachialis tendon was attached to the coronoid process at a mean distance of 12.1 mm distal to the tip.

Conclusion: The coronoid process of the ulna is a small osseous structure with a complex anatomy and presents some anatomical variations.