[The exit of the chorda tympani nerve through the external surface of the base of the skull].

Current textbooks of anatomy consider the chorda tympani to leave the external surface of the base of the skull through the petrotympanic fissure (of Glaser). In contrast to this view, Krause in 1905 described the sphenopetrosal fissure as outlet structure. The present reexamination of the extracranial course of 33 chordae tympani confirms the latter conception. Thus, the prevailing opinion has to be revised. Clinical impacts are discussed.