extensor carpi ulnaris tendon ( RID2382 )
In image 1, despite pronated wrist positioning (note the dorsal ulnar groove points medially, in neutral it would point roughly to 12:00), there is medial dislocation of the intact ECU; this implies chronic ECU subsheath tear. In the Sag images, I believe there is a chronic low grade sprain of the foveal insertion of the dorsal band distal radioulnar ligament (yellow arrows). In the Cor images, there may be fraying of the dorsal aspect of the foveal lamina TFCC. [ Article ]
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