Vessels and nerves of the organ of vision

The eyeball and its accessory organs receive blood from the branches of the ophthalmic artery, which in turn is a branch of the internal carotid artery. Venous blood from the organ of vision flows through the ophthalmic veins into the cavernous sinus. The retina is supplied with blood by the central retinal artery (a. centralis retinae), which penetrates into the eyeball in the thickness of the optic nerve and gives off upper and lower branches in the region of the disk. The central retinal vein and its tributaries are adjacent to the arteries of the same name. In the choroid, short and long posterior and anterior ciliary arteries branch. The branches of these arteries in the thickness of the iris anastomose with each other and form two arterial circles: a large one (circulus arteriosus iridis major) at the ciliary edge of the iris and a small one (circulus arteriosus iridis minor) at the pupillary edge. The sclera is supplied with blood by the posterior short ciliary arteries. From the dense venous network of the choroid proper, 4-6 vorticose veins (vv. vorticosae) are formed, which pierce the sclera and flow into the orbital veins. The anterior ciliary veins collect blood from the ciliary body, iris, and sclera.

The eyelids and conjunctiva receive blood from the medial and lateral arteries of the eyelids, anastomoses between which form the arch of the upper eyelid and the arch of the lower eyelid in the thickness of the eyelids, and the anterior conjunctival arteries. The veins of the same name flow into the ophthalmic and facial veins. The lacrimal artery (a. lacrimalis) goes to the lacrimal gland.

The muscles, fascia, and fat pad of the orbit are also supplied with blood by branches of the ophthalmic artery. Lymphatic vessels from the eyelids and conjunctiva are directed to the submandibular and also to the superficial and deep parotid (preauricular) lymph nodes.

The eye socket contents receive sensory innervation from the first branch of the trigeminal nerve, the ophthalmic nerve. Its branch, the nasociliary nerve, gives rise to long ciliary nerves that reach the eyeball. The lower eyelid is innervated by the infraorbital nerve, which gives off the second branch of the trigeminal nerve. The constrictor pupillae muscle and the ciliary muscle receive parasympathetic fibers of the oculomotor nerve (from the ciliary ganglion as part of the short ciliary nerves). The pupil dilator muscle is innervated by sympathetic fibers of the internal carotid plexus, which reach the eyeball along with the blood vessels. The superior, inferior, and medial rectus muscles, the inferior oblique muscle of the eye, and the muscle that raises the upper eyelid are innervated by motor fibers from the oculomotor nerve, the lateral rectus muscle is innervated by the abducens nerve, and the superior oblique muscle is innervated by the trochlear nerve.