Sesamoid bone of tendon of supinator muscle

The sesamoid bone of tendon of supinator muscle is found in the tendon of origin of this muscle, at the level of the elbow. In the dogs, the supinator muscle originates from the lateral epicondyle of the humerus, by means of a thick tendon. This tendon passes distally to the cranio-lateral aspect of the head of the radius. At this level, an oval-shaped sesamoid bone may develop inside the tendon of the supinator muscle, which articulates with the head of the radius.

In a study of 100 dogs, sesamoid bone of tendon of supinator muscle was visible on CT scan in 26% of cases and bilateral in 76.92% of cases. It was found radiographically in 8.33% of cases. It is important to recognise the presence of the sesamoid bone of tendon of supinator muscle so as not to confuse it with a fragmentation of the head of the radius, for example. A positive correlation has been suggested between elbow disease (dysplasia in particular) and the presence of the sesamoid bone of the supinator tendon.