The document summarizes the orbital blood supply. The ophthalmic artery is the first main branch of the internal carotid artery and gives rise to numerous branches that supply the orbit and eye. These branches include the central retinal artery, lacrimal artery, muscular branches, and ciliary arteries. The central retinal artery supplies the retina. The lacrimal artery supplies the lacrimal gland and eyelids. Venous drainage is mainly through the superior and inferior ophthalmic veins which drain into the cavernous sinus.