Orbital Septum Posterior to Medial Canthal Tendon Area

Purpose: To examine the anatomy of the orbital septum posterior to the medial canthal tendon area.

Materials and methods: We performed 3 anatomical dissections in the present study. The first one was a microscopic study in which exenterated specimens from 6 Japanese cadavers (age from 77 to 93 years at death) were cut inferno-horizontally, including the Müller muscle, medial rectus pulley, and lateral rectus pulley, and stained with Masson's trichrome. The second one was also a microscopic study in which the exenterated specimens from 5 Japanese cadavers (age from 73 to 87 years at death) were cut horizontally, 1 mm superior to the upper eyelid margin and 1 mm inferior to the lower eyelid margin, and stained with Masson's trichrome. The third one was a macroscopic study in which exenterated specimens from 5 Japanese cadavers (age from 73 to 91 years at death) were cut horizontally at the medial palpebral commissure.

Results: In the first study, all the specimens showed the orbital septa with close vicinity to the orbicularis oculi muscle in the medial area. The second and third studies both demonstrated the double lamellar structure of the medial canthal tendon area. The anterior one was the fibrous tissue corresponding to the white medial canthal tendon. The posterior one referred to the preseptal orbicularis oculi muscle. The orbital septum was located directly posterior to this muscular structure.

Conclusion: The orbital septum posteriorly lined the preseptal orbicularis oculi muscle, the muscular part of the medial canthal tendon.