Hyrtl fissure is an anatomic landmark allowing a transient embryonic communication between the subarachnoid space and the middle ear. It is an eponym characterized by the absence of a known original description. The aim of this study was to try to find and explain the origin of the use of this eponym. Numerous references and original publications were studied to finally demonstrate that Joseph Hyrtl was not able to describe this fissure in the mid-19th century.