SOFT TISSUE MASSES IMMEDIATELY BELOW THE FORAMEN MAGNUM.
D001139:Arnold-Chiari Malformation; D001932:Brain Neoplasms; D014695:Cerebral Ventriculography; D003952:Diagnostic Imaging; D005539:Foramen Magnum; D006801:Humans; D011859:Radiography
ARNOLD-CHIARI DEFORMITY; BRAIN NEOPLASMS; VENTRICULOGRAPHY