Matteo de Notaris1, Alberto Prats-Galino2. 1. Department of Human Anatomy and Embryology, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain; Department of Neurosurgery, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain. Electronic address: matteodenotaris@gmail.com. 2. Department of Human Anatomy and Embryology, Faculty of Medicine, Universitat de Barcelona, Barcelona, Spain.