Glasscock originally defined the corners as the posterior rim of the foramen ovale, the apex of the cochlea, and the posterior border of the mandibular division of the trigeminal nerve ¹⁾.

: posterior rim of foramen ovale and third branch of the trigeminal nerve (anterior border), the line from the arcuate eminence to the posteromedial corner of gasserian ganglion, and the line between the foramen spinosum and arcuate eminence. Through this triangle, the following important structures may be accessed: the great superficial petrosal nerve, the intrapetrous carotid artery (C6), the tensor tympani muscle and the eustachian tube.