Which structure lies anterior to the optic nerve?

• A. Optic canal
• B. Oculomotor nerve
• C. ophthalmic artery
• D. Retina

Answer: (C)

The ophthalmic artery is the correct answer because it branches from the internal carotid artery and enters the orbit through the optic canal, usually lying anterior to the optic nerve. This positioning allows it to supply blood to various structures in the eye and surrounding areas, while the optic nerve, responsible for vision, lies posterior to the ophthalmic artery as it traverses the orbit.

The other structures mentioned do not exhibit this anterior positioning relative to the optic nerve. The optic canal is simply the passageway through which the optic nerve and ophthalmic artery exit the skull into the orbit, making it a more posterior structure when considering their relative positions. The oculomotor nerve, which innervates several extraocular muscles, also lies more medial and anterior to the optic nerve but not necessarily anterior to the ophthalmic artery itself. Finally, the retina is located at the back of the eye, which positions it posteriorly, well behind the optic nerve.