Anatomy of the medial wall of the orbit undergoing an endoscopic endonasal approach: An inferomedial and superomedial approach.

Background: Endoscopic endonasal corridor is valuable for accessing and treating midline skull base pathologies. In the present work, we will discuss the anatomy of the medial wall of the orbit from an endonasal endoscopic perspective.

Methods: Six human cadaveric specimens underwent endonasal endoscopic dissection at the Surgical Neuroanatomy Laboratory of the Mexican Faculty of Medicine of La Salle University. We used a 0°, 4 mm diameter, and 18 cm length rigid endoscope using a 4K high-definition neuro-endoscopic visualization system, specialized surgical instruments for endonasal endoscopic surgery, and a high-speed drilling system.

Results: In the endonasal endoscopic to the medial wall of the orbit, we describe two approaches: the superomedial approach (SMA) and the inferomedial approach (IMA). The SMA is located between the lower border of the superior oblique muscle and the superior border of the medial rectus muscle (MRM), and the IMA is located between the inferior border of the MRM and the superior border of the inferior rectus muscle. The topographic anatomy of the contents of each approach is described.

Conclusion: The endoscopic endonasal corridor safely reaches the medial half of the orbit through the inferomedial and SMAs.