Minor Arterial Circle of the Iris, Gross Anatomy

Description

Arising within the ciliary body, the long posterior ciliary arteries course anteriorly toward the iris root, where their radial branches (iris arterioles) run centrally through the iris stroma toward the pupillary margin. Near the collarette, these branches interconnect as the minor arterial circle of the iris, an anastomotic ring positioned concentric to the pupil and medial to the peripheral iris. Anteriorly, the cornea and anterior chamber frame the iris, while the lens sits posterior to the pupillary aperture. Posteriorly, the choroid and retina are partially exposed, and the optic nerve exits at the posterior pole. For teaching ocular perfusion, the lesser arterial circle matters because it explains why sectoral iris ischemia follows interruption of the major inflow pathways, and why neovascularization of the iris (rubeosis iridis) often tracks along preexisting stromal vessels toward the pupillary zone. This ring also sits in the operative neighborhood for anterior segment procedures, including iridectomy and iris manipulation during cataract surgery, where bleeding patterns can be predicted by the radial arterioles that feed into the circle. Small circle, real consequences. Use this plate in ophthalmic anatomy courses to contrast the major arterial circle at the iris root with the minor arterial circle nearer the pupil, and in clinical education materials discussing hyphema, uveitis-related vascular congestion, or anterior segment ischemia after ocular trauma. It also suits publishing needs for atlases and journal figures on iris vascular anatomy, angiogenesis, and surgical landmarks in the anterior chamber. Anatomical accuracy verified by SciePro's Medical Advisory Board.