Orbital septum

Orbital septum
The right eye in sagittal section, with structures of the orbital septum within blue markings.
Details
Identifiers
Latin	Septum orbitale
TA	A15.2.07.003
FMA	59328
Anatomical terminology []

The orbital septum (Palpebral fascia) is a membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids.

In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate.

When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the medial palpebral ligament, attaches to the lacrimal bone at its posterior crest. The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves.

The septum is perforated by the vessels and nerves which pass from the orbital cavity to the face and scalp.

With age the septum may weaken, and as a result orbital fat may herniate forwards. The operation to correct this is called blepharoplasty.

The orbital septum is an important landmark in distinguishing between orbital cellulitis (inside the septum) and periorbital cellulitis (outside the septum).

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)