<Li> Medial margin: ethmoid, lacrimal bone, sphenoid (body of) and maxilla </Li> <Li> Lateral margin: zygomatic and sphenoid (greater wing) </Li> <P> The orbit holds and protects the eye . </P> <P> The movement of the eye is controlled by six distinct extraocular muscles, a superior, an inferior, a medial and a lateral rectus, as well as a superior and an inferior oblique . The superior ophthalmic vein is a sigmoidal vessel along the superior margin of the orbital canal that drains deoxygenated blood from surrounding musculature . The ophthalmic artery is a crucial structure in the orbit, as it is often the only source of collateral blood to the brain in cases of large internal carotid infarcts, as it is a collateral pathway to the circle of Willis . In addition, there is the optic canal, which contains the optic nerve, or cranial nerve II, and is formed entirely by the lesser wing of the sphenoid, separated from the supraorbital fissure by the optic strut . Injury to any one of these structures by infection, trauma or neoplasm can cause temporary or permanent visual dysfunction, and even blindness if not promptly corrected . The orbits also protect the eye from mechanical injury . </P>

What bone contribute to the formation of the orbit