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
((Glassock ME 3rd, Jackson CG, Dickins JR, Wiet RJ. Panel discussion: glomus jugulare tumors of the temporal bone. The surgical management of glomus tumors. Laryngoscope. 1979 Oct;89(10 Pt 1):1640-54. doi: 10.1002/lary.5540891015. PMID: 228135.)).
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: 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.