Which of the following is NOT one of the major regions of the optic nerve?

Which of the following is NOT one of the major regions of the optic nerve?

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

Answer: (C)

Optic nerve regions are four: intraocular, intraorbital, intracanalicular, and intracranial. The term intralamellar isn’t a recognized regional segment of the nerve—the lamina cribrosa is a sieve-like structure at the optic nerve head, not a separate part of the nerve’s course. So this option isn’t one of the major regions. The intraocular portion lies within the eye from the optic disc to the lamina cribrosa; the intraorbital portion runs from the posterior globe to the optic canal; the intracanalicular portion travels through the optic canal; the intracranial portion continues beyond the canal to the optic chiasm.

Optic nerve regions are four: intraocular, intraorbital, intracanalicular, and intracranial. The term intralamellar isn’t a recognized regional segment of the nerve—the lamina cribrosa is a sieve-like structure at the optic nerve head, not a separate part of the nerve’s course. So this option isn’t one of the major regions. The intraocular portion lies within the eye from the optic disc to the lamina cribrosa; the intraorbital portion runs from the posterior globe to the optic canal; the intracanalicular portion travels through the optic canal; the intracranial portion continues beyond the canal to the optic chiasm.