FCEM2-1246

A 32-year-old woman experiences a fracture-dislocation of her forearm after tripping and landing on her outstretched hand. As a result, she has developed weakness in her wrist and finger extensors and experiences pain in her proximal forearm. The weakness in her wrist extensors is only partial, but it is observed that wrist extension causes radial deviation of the wrist. There are no sensory abnormalities.
Which nerve has been affected in this case?