Embryonal atresia of the fourth ventricle. The cause of "arachnoid cyst" of the cerebellopontine angle.
D016080:Arachnoid Cysts; D001927:Brain Diseases; D002530:Cerebellopontine Angle; D002552:Cerebral Ventricles / Q000002:abnormalities*; D003560:Cysts / Q000209:etiology*; D004194:Disease; D020546:Fourth Ventricle; D006801:Humans
CEREBELLOPONTILE ANGLE/diseases; CEREBRAL VENTRICLES/abnormalities; CYSTS/etiology