Anatomy of the superior border of the lateral orbital wall: Surgical implications in deep lateral orbital wall decompression surgery

Purpose: To present the anatomical characteristics of the superior border of the lateral orbital wall and thereby reduce the risk of inadvertent dural damage during deep lateral orbital wall decompression. Methods: Twenty-five orbits (13 right and 12 left) of 13 Asian cadavers (6 men and 7 women) aged 61 to 93 years at death (average, 79.5 years) were used. After removing the orbital content, the lateral orbital wall, and the skull and brain, the superior border of the lateral orbital wall was exposed, which was analyzed from an orbital cavity view and an intracranial cavity view. Results: The anterior part of the superior border of the lateral orbital wall is parallel with the orbital roof; however, more posteriorly, as the orbital roof curves inferiorly, they become perpendicular. The cortical bone conspicuously separates the thin superior border from the orbital roof. In the junction between the superior and the posterior borders, a thick bone marrow exists. Complete removal of this bone marrow resulted in penetration in the junction of the anterior and middle cranial fossae. Conclusion: The authors documented the anatomy of the superior border of the lateral orbital wall, including the different relative positions between the superior border and the orbital roof in the anterior and posterior parts of the orbit. To avoid dural exposure, the cortical bone should not be exposed at the junction between the superior and posterior borders of the lateral orbital wall, which corresponds to the junction of the anterior and middle cranial fossae.