Groove in the base of the skull fitting the Eustachian canal
The lateral half of the great wing of the sphenoid bone articulates, by means of a synchondrosis, with the petrous part of the temporal bone. Between these two bones on the under surface of the skull, is a furrow, the 'sulcus of auditory tubule, for the lodgement of the cartilaginous part of the auditory tube.
References
This article incorporates text in the public domain from page 150 of the 20th edition of Gray's Anatomy (1918)