2020–2021 BCSC Basic and Clinical Science Course™
7 Oculofacial Plastic and Orbital Surgery
Part I: Orbit
Chapter 1: Orbital Anatomy
Vasculature of the Orbit
The blood supply to the orbit arises primarily from the ophthalmic artery (Figs 1-7, 1-8), which is a branch of the internal carotid artery. Smaller contributions come from the external carotid artery by way of the internal maxillary and facial arteries. The ophthalmic artery travels underneath the intracranial optic nerve through the dura mater along the optic canal to enter the orbit. The major branches of the ophthalmic artery are the
branches to the extraocular muscles
central retinal artery (to the optic nerve and retina)
posterior ciliary arteries (long to the anterior segment and short to the choroid)
Terminal branches of the ophthalmic artery travel anteriorly and form rich anastomoses with branches of the external carotid in the face and periorbital region (Fig 1-9).
The superior ophthalmic vein provides the main venous drainage of the orbit (see Figs 1-7, 1-8). This vein originates in the superonasal quadrant of the orbit and extends posteriorly through the superior orbital fissure into the cavernous sinus. Frequently, the superior ophthalmic vein appears on axial orbital CT scans as the only structure coursing diagonally through the superior orbit. Many anastomoses occur anteriorly with the veins of the face as well as posteriorly with the pterygoid plexus.
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.