Anatomy of the Medial Orbit and Various Approaches to Access It

Background: The medial orbit can be the site of several pathological lesions such as cavernomas, neurinomas, and lymphomas. However, approaching the medial orbit remains a challenging task because of the narrow surgical corridors, surrounding critical neural structures, and complicated vascular relationships.

Objective: To examine the microsurgical anatomy of the medial orbit and compare the various surgical approaches to access it.

Methods Ten adult cadaveric specimens were examined using magnifications ranging from 3× to 40× after perfusion of the arteries and veins with colored silicone. The microsurgical anatomy of the medial orbit and surgical approaches to it were examined. The transsinus approach was performed using 0- or 45-degrees rigid endoscopes, and other approaches were performed using the surgical microscope.

Results: The surgical approaches to the medial orbit can be classified into three categories: (1) transcranial approach; (2) trans-sinus approaches: transethmoidal and transmaxillary approaches; and (3) transorbital approaches: precaruncular and medial orbital approaches. The transcranial approach exposes the superior and medial surfaces of the orbit and the optic apex widely. The trans-sinus approach exposes the medial and inferior surfaces of the orbit and optic nerve. The transorbital approach exposes the anterior and medial surfaces of the orbit, but the surgical corridor to the optic canal and apex in this approach is relatively narrower and deeper compared with that in the previous two approaches.

Conclusion: The knowledge of the microsurgical anatomy of the medial orbit and surrounding critical structures and the selection of an appropriate surgical approach will make surgical procedures safe and precise.

Keywords: medial orbit, orbital tumor, transorbital approach