The brainstem and cerebellum protrude through the foramen magnum in Type II Chiari Malformation. Abnormality highlighted.
Chiari Malformation: Type 2
In Type 2 Chiari Malformation (aka Arnold-Chiari malformation), the cerebellum and brainstem protrude into the foramen magnum; the cerebellar vermis may be absent; and it typically accompanies a myelomeningocele (a form of spina bifida).