**Acknowledgements**

The authors would like to acknowledge Dr. Michael Flanagan's numerous contributions to the literature and his seminal writings on the anatomy of the craniocervical junction and the role of cerebrospinal fluid in brain function and health. https://uprightdoctor.wordpress.com/ about-dr-michael-flanaga/

Special thanks to Ron Tribell and Axis Medical Illustrations for the illustrations at **Figures 1**, **3**, **7** and **8**.
