Book of the Ten Treatises of the Eye the sclera, a thick, hard membrane which protects the inner parts of the nerves from injury. The chorioid, a thin and soft structure filled with veins and arteries, follows next and provides nourishment to the overall structure. Finally, the retina transmits nutrients to the lenses themselves. Hunayn then presents the system responsible for protecting the eye. From the outermost level, these are the conjunctiva, cornea, and uvea. While both the conjuctiva and cornea provide protection with minimizing hindrance to the lenses, the uvea has an extra function of concentrating the pneuma exiting out of the eye to prevent it from
Short ciliary nerves the inner surface of the sclera, and are distributed to the ciliary muscle, iris, and cornea. The short ciliary nerve contains parasympathetic and sympathetic nerve fibers. The parasympathetics arise from the Edinger-Westphal nucleus and synapse in the ciliary ganglion via the oculomotor nerve, the postganglionic parasympathetics leave the ciliary ganglion in the short ciliary nerve and supply the ciliary body and iris. Sympathetics are provided by the superior cervical ganglion and they reach the ganglion either as branches of the nasociliary nerve or directly from the extension of the plexus on the ophthalmic artery (sympathetic branch to ciliary ganglion). Damage