The meningo-orbital foramen in a Scottish population.

The meningo-orbital foramen is a small opening in the orbit lateral to the lateral end of the superior orbital fissure. It is widely reported to contain an orbital branch of the middle meningeal artery. The foramen may be single or multiple and may occur in the posterosuperior part of the lateral orbital wall or in the posterolateral part of the orbital roof. There is a lack of clarity in the literature as to whether foramina occurring in the orbital roof are the same entity as those occurring in the lateral wall. The disposition of the lesser wing of the sphenoid at the anterior limit of the middle cranial fossa makes it difficult to see how a foramen communicating with the anterior cranial fossa could transmit a branch of the middle meningeal artery. Our study contained 16 meningo-orbital foramina in the orbital roof that would transmit a fine probe. Fourteen of these passed into canals that tracked posteriorly in the bone to open into the middle cranial fossa close to the lateral extremity of the superior orbital fissure. The other two of these foramina communicated with the anterior cranial fossa and both were associated with a more posterior foramen that communicated with the middle cranial fossa. We hope this study clarifies an issue with relevance to surgery in the anterior cranial fossa.