1. Department of Otolaryngology-Head and Neck Surgery, Tohoku University School of Medicine, Sendai, Japan
2. Department of Anatomy, Tokyo Dental College, Tokyo, Japan
3. Department of Anatomy and Embryology, School of Medicine, Complutense University of Madrid, Madrid, Spain
4. Division of Internal Medicine, Cupid Clinic, Iwamizawa, Japan
5. Akita University School of Medicine, Akita, Japan