In some individuals, an additional nasal vein passes superiorly through a midline aperture (the foramen cecum), in the frontal bone anterior to the crista galli, and joins with the anterior end of the superior sagittal sinus. Because this nasal vein connects an intracranial venous sinus with extracranial veins, it is classified as an emissary vein. Emissary veins in general are routes by which infections can track from peripheral regions into the cranial cavity.