Measurements of the skull base for transpetrosal surgery

To understand the anatomy and the surgical approaches to the petrous, 19 adult human skulls (38 specimens) were studied. The foramen spinosum, groove for greater petrosal nerve, superior and posterior margins of the internal auditory meatus, fissure for the endolymphatic sac, and anterior margin of the groove for sigmoid sinus were the constant, easily identifiable bony landmarks located strategically; they served as guides during the transpetrosal approach. Measurements between various points helped both to understand the local anatomy better and to decide the degree and direction of safe bony removal during transpetrosal surgery.