Trauma to the upper extremity presents difficulties in diagnosis because of the complexity of the anatomy and of the structures involved. These injuries are common, representing more that 45% of all injuries coming to a walk-in emergency center. Commonly missed or misdiagnosed injuries are listed below with clinical examples. Posterior dislocation of the shoulder or perilunar dislocations of the carpus are still commonly missed today in spite of ample information in all medically oriented media. This series of articles is tended to warn emergency room practitioners of the these traps for the unwary.