Middle Skull Base and Its Openings Viewed from Below

Abstract

The mandibular nerve traverses the foramen ovale, which in our material is 7.2 (2.2–9.9) mm long and 3.7 (1.7–6.5) mm wide. Its long axis is generally oblique, being directed from anteromedially to posterolaterally. The distances between the foramina ovale (and other external openings in the skull base) in adults are pictured in Fig. SA 36. The mandibular nerve is surrounded by a venous plexus called the venous plexus of the foramen ovale, which communicates inferiorly with the pterygoid venous plexus and intracranially with the veins accompanying the middle meningeal artery and with the cavernous sinus. In about 30% of cases a foramen of Vesalius is present which transmits a sphenoidal emissary vein. Generally these openings in the external skull base are found about the upper border of the pterygoid fossa.