Periorbita

The periorbita (orbital periosteum; orbital fascia) is a dense connective tissue membrane that covers the bones of the orbit. It serves as an attachment site for muscles, tendons, and ligaments and is a support structure for the blood supply to the orbital bones.

The periorbita is attached only loosely to the underlying bone except at the orbital margins, the sutures, and the edges of fissures and foramina:

• At the orbital margins, the orbita is continuous with the periosteal covering of the bones of the face

• At the edges of the superior orbital fissure, the optic canal, and the ethmoid canals, the periorbita is continuous with the periosteal layer of the dura mater.

• At the anterior portion of the optic canal, the periorbita splits such that a portion becomes continuous with the dura of the optic nerve and another portion reflects forward to take part in the formation of the common tendinous ring.

• At the inferior orbital fissure the periorbita is continuous with the periosteum of the skull. At the lacrimal crests a sheet of periorbita covers the lacrimal sac, and the periorbita is continuous with the tissue lining the nasolacrimal canal. Another portion of the periorbita covers the lacrimal gland.

Lee Ann Remington OD, MS, FAAO, in Clinical Anatomy and Physiology of the Visual System (Third Edition), 2012