The eminent anatomists who discovered the upper oesophageal sphincter

To discover the anatomist who first identified the upper oesophageal sphincter. The authors searched dozens of antique anatomy textbooks kept in the old section of the 'Vincenzo Pinali' Medical Library of Padua University, looking for descriptions of the upper oesophageal sphincter. The oesophageal sphincter was drawn correctly only in 1601, by Julius Casserius, in the book De vocis auditusque organis historia anatomica… (which translates as 'An Anatomical History on the Organs of Voice and Hearing …'), and was properly described by Antonio Maria Valsalva in 1704 in the book De aure humana tractatus… ('Treatise on the Human Ear …'). Anatomists Casserius and Valsalva can be considered the discoverers of the 'oesophageal sphincter'.