The orbital margin, or rim, forms a quadrilateral spiral whose superior margin is formed by the frontal bone, which is interrupted medially by the supraorbital notch (Fig 1-2). The medial margin is formed above by the frontal bone and below by the posterior lacrimal crest of the lacrimal bone and the anterior lacrimal crest of the maxillary bone. The inferior margin derives from the maxillary and zygomatic bones. Laterally, the zygomatic and frontal bones complete the rim.
Figure 1-2 Right orbital roof. The orbital roof is composed of 2 bones: (1) the orbital plate of the frontal bone; and (2) the lesser wing of the sphenoid bone. The frontal sinus lies within the anterior orbital roof. The supraorbital foramen/notch, located within the medial one-third of the superior orbital rim, transmits the supraorbital nerve, a terminal branch of the frontal nerve of the ophthalmic division of cranial nerve V (CN V1). Medially, the frontal bone forms the roof of the ethmoid sinus and extends to the cribriform plate.
(Illustration by Dave Peace.)
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.