Abstract:

Objective　To provide anatomic data of the cranio-orbital foramen and the lateral orbital sulcus for the skull base surgery.　Methods　One hundred dry adult skulls (200 sides) and 30 cadaveric heads (60 sides) were observed and measured, for exploring anatomic features and variations of the cranio-orbital foramen and its adjacent structures.　Results　Incidence of the cranio-orbital foramen was 65.5% (131 sides). The cranio-orbital foramen located on the greater wing of the sphenoid bone, or on the frontal bone, at or near the spheno-frontal suture. Usually, 1-3 foramens could be observed. Incidence of the lateral orbital sulcus was 24% (48 sides). No artery was observed to pass through the sulcus of cadaveric heads. The course of the orbital branch of the middle meningeal artery could be divided into 3 types. For typeⅠ, the orbital branch of the middle meningeal artery entered the orbit through the cranio-orbital foramen and anastomosed with the lacrimal artery. For typeⅡ, the paired orbital branches of the middle meningeal artery entered the orbit through the superior orbital fissure and the cranio-orbital foramen and anastomosed with the lacrimal artery. For type Ⅲ, the orbital branch of the middle meningeal artery entered the orbit through the superior orbital fissure and anastomosed with the lacrimal artery.　Conclusions　The cranio-orbital foramen, the lateral orbital sulcus, and their adjacent structures are complex and variable, which need to be taken notice during the surgical procedure in this area.

Key words: Cranio-orbital foramen, Middle meningeal artery, Orbit, Sphenoid bone, Skull base