Which portion of the optic nerve is the longest?

• A. Intraocular
• B. Intraorbital
• C. Intracanalicular
• D. Intracranial

Answer: (B)

Understanding how the optic nerve is segmented helps explain why the intraorbital portion is the longest. After the nerve forms from retinal ganglion cell axons, it travels from the back of the eyeball through the orbit to reach the optic canal. This stretch within the orbital cavity is the greatest distance, roughly 25–30 millimeters, making it the longest segment. The portion that goes through the optic canal is much shorter, about 7–10 millimeters, and the intracranial segment is also relatively short, around 10–15 millimeters. The intraocular portion stays within the eye itself and is the shortest. So, the intraorbital path spans the most distance, which is why it’s the longest.