Accidents of the Embryo:

Spina Bifida and Variations at Birth

Chapter 8
Arnold Chiari Malformations

& Foramen Magnum Syndrome
The lower part of the brain or cerebellum can be abnormally positioned so that it extends down through the foramen magnum – the opening at the base of the skull. If it crowds the spinal cord in this location, a variety of symptoms including headache and neck pain can result.