&Posterior Interosseous Nerve Entrapment Syndrome=Posterior interosseous nerve entrapment in the radial tunnel produces discomfort in the proximal lateral portion of the forearm. Pt will be unable to extend thumb or other digits at MCPs. Posterior interosseous nerve, a branch of radial nerve, is primarily a motor nerve, so sensory disturbances are rare. Repetitive activity with forceful supination, wrist extension, or radial deviation against resistance may be a factor. Direct trauma and such non traumatic conditions as a ganglion also have been implicated.