any structural anomaly of the circular aperture (foramen) located in the middle cranial fossa, inferomedial to the superior orbital fissure at the base of greater wing of sphenoid; its medial border is formed by the lateral wall of the sphenoid sinus; it runs downwards and laterally in an oblique path and joins the middle cranial fossa with the pterygopalatine fossa; it transmits the maxillary branch of trigeminal nerve, artery of foramen rotundum, and emissary veins