1. Department of Otolaryngology‐Head and Neck Surgery Tohoku University Graduate School of Medicine Sendai Japan
2. Department of Anatomy, School of Medicine International University of Health and Welfare Narita Japan
3. Department of Anatomy Akita University School of Medicine Akita Japan
4. Division of Internal Medicine Jikou‐kai Clinic of Home visits Sapporo Japan
5. Department of Anatomy and Embryology, School of Medicine Complutense University Madrid Spain
6. Department of Maxillofacial Anatomy Graduate School of Tokyo Medical and Dental University Tokyo Japan