Resluts All the 14 cases showed clivus projecting intracranial.posterior displacement of Odontoid Process were found in 3 cases,with 1 case of Atlanto-occipita fusion malformation.

14MR矢状位像均示颅内陷入,3见齿状突后移,1合并寰枕融合畸形,14均清示了延颈髓的形态及与小脑扁桃体的关系。