Ulnar nerve compression due to an anomalous muscle in the canal of Guyon.
D000328:Adult; D006801:Humans; D008297:Male; D009132:Muscles / Q000002:abnormalities*; D009408:Nerve Compression Syndromes / Q000209:etiology / Q000601:surgery; D010523:Peripheral Nervous System Diseases / Q000209:etiology*; D014459:Ulnar Nerve; D014953:Wrist / Q000002:abnormalities*