Where is the orbit? Definition of orbital septum attachment sites.

Abstract

The orbit is defined as the space posterior to the orbital septum. While the orbital septum's attachment to the bone and soft tissues in the superior and inferior regions has been well documented, its attachment in the medial and lateral canthal areas remains controversial. Consequently, the definition of the orbit in these regions is uncertain. In this study, we aim to precisely define the orbital area.

Superior area: The orbital septum originates from the arcus marginalis and attaches to the levator aponeurosis several millimeters above the upper tarsal plate.

Inferior area: It similarly arises from the arcus marginalis nasally but extends beyond the orbital margin temporally, reaching the anterior surface of the maxillary bone. The space between the orbital septum and the maxillary bone is called the recess of Eisler. The orbital septum's attachment to the lower eyelid retractors is located several millimeters below the lower tarsal plate.

Medial canthal area: The orbital septum originates from the anterior lacrimal crest, not the posterior lacrimal crest. In relation to the medial canthal tendon, it faces the posterior surface of this tendon.

Lateral canthal area: The orbital septum originates from the arcus marginalis and attaches to the levator aponeurosis and lower eyelid retractors around the temporal palpebral commissure. It does not attach directly to the orbital tubercle; instead, a space filled with orbital fat exists between the orbital septum and the levator aponeurosis-lower eyelid retractors.