Summary

Objective: To describe the anatomic relationship of the biceps brachii-brachialis muscle complex and the medial compartment of the canine elbow. Study design: Anatomical cadaveric study. Methods: Cadaveric forelimbs, and radius and ulna bones were examined to study the anatomy of the biceps brachii-brachialis complex and its relationship to the medial compartment of the elbow. Results: The biceps brachii and brachialis muscles comprise a large muscular complex. The biceps brachii is a pennate fibred muscle which plays a major role in stabilising the elbow joint during the stance phase and facilitating limb acceleration during the swing phase. Additionally, the insertion of the muscular complex onto the ulnar tuberosity is such that a moment is generated which the authors hypothesise rotates the medial coronoid process against the radial head. The result is a compressive force which generates internal shear stress oblique to the long axis of the medial coronoid process. The authors further hypothesise that this may result in the microdamage or fragmentation of the medial coronoid process. Conclusion: The authors' conclude that contraction of the biceps brachii and brachialis complex may explain an aetiopathogenesis for fragmented medial coronoid process not associated with elbow dysplasia.