Blood vessels of the Orbit

• Is a branch of the internal carotid artery and enters the orbit through the optic canal beneath the optic nerve.
• Gives rise to the ocular and orbital vessels , which include the following:

1. Central artery of the retina

• Is the most important branch of the ophthalmic artery.
• Travels in the optic nerve; it divides into superior and inferior branches to the optic disk, and each of those further divides into temporal and nasal branches.
• Is an end artery that does not anastomose with other arteries, and thus its occlusion results in blindness.

2. Long posterior ciliary arteries

• Pierce the sclera and supply the ciliary body and the iris.

3. Short posterior ciliary arteries

• Pierce the sclera and supply the choroid.

4. Lacrimal artery

• Passes along the superior border of the lateral rectus and supplies the lacrimal gland, conjunctiva, and eyelids.
• Gives rise to two lateral palpebral arteries , which contribute to arcades in the upper and lower eyelids.

5. Medial palpebral arteries

• Contribute to arcades in the upper and lower eyelids.

6. Muscular branches

• Supply orbital muscles and give off the anterior ciliary arteries, which supply the iris.

7. Supraorbital artery

• Passes through the supraorbital notch (or foramen) and supplies the forehead and the scalp.

8. Posterior ethmoidal artery

• Passes through the posterior ethmoidal foramen to the posterior ethmoidal air cells.

9. Anterior ethmoidal artery

• Passes through the anterior ethmoidal foramen to the anterior and middle ethmoidal air cells, frontal sinus, nasal cavity, and external nose.

10. Supratrochlear artery

• Passes to the supraorbital margin and supplies the forehead and the scalp.

11. Dorsal nasal artery

• Supplies the side of the nose and the lacrimal sac.

1. Superior ophthalmic vein

• Is formed by the union of the supraorbital, supratrochlear, and angular veins.
• Receives branches corresponding to most of those of the ophthalmic artery and, in addition, receives the inferior ophthalmic vein before draining into the cavernous sinus.

2. Inferior ophthalmic vein

• Begins by the union of small veins in the floor of the orbit.
• Communicates with the pterygoid venous plexus and often with the infraorbital vein and terminates directly or indirectly in the cavernous sinus.