The foramen meningo-orbitale and its relationship to the development of the ophthalmic artery.

The incidence of the foramen meningo-orbitale is reported from a sample of 50 adult dried skulls. The foramen meningo-orbitale is not an inconsistent finding, being identifiable in half of the samples studied. Multiple foramina may exist. Although the location of the foramen meningo-orbitale is not fixed, it lies along or near the suture leading superolaterally from the superior orbital fissure. The foramen represents the remnant of an embryonic conduit for the supraorbital division of the stapedial artery en route to the orbit and the developing ophthalmic artery. An alternative, more medial, pathway exists through the superior orbital fissure. The embryonic anastomosis that occurs between the internal and external carotid systems does not occur at the level of this foramen, but closer to the optic nerve as a portion of the primitive 'ring' artery. The term 'stapedial-ophthalmo-lacrimal' foramen is proposed to proclaim the embryonic significance of this foramen.