The orbital septum arises anteriorly from the orbital rim. The paranasal sinuses are either rudimentary or very small at birth, and they increase in size through adolescence. They lie adjacent to the floor, medial wall, and anterior portion of the orbital roof. The orbital walls are composed of 7 bones: ethmoid, frontal, lacrimal, maxillary (maxilla), palatine, sphenoid, and zygomatic. The composition of each of the 4 walls and their location in relation to adjacent extraorbital structures are shown in Figures 1-1, 1-2, and 1-3 and summarized in the following sections.
Roof of the Orbit
The roof of the orbit is composed of the orbital plate of the frontal bone and the lesser wing of the sphenoid bone. It is located adjacent to the anterior cranial fossa and frontal sinus and includes the following important landmarks:
the fossa of the lacrimal gland, which contains the orbital lobe of the lacrimal gland
the fossa for the trochlea of the superior oblique tendon, located 5 mm behind the superonasal orbital rim
the supraorbital notch, or foramen, which transmits the supraorbital vessels and the supraorbital branch of the frontal nerve
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.