Optic nerve meningioma arises from ?

Ans. is 'd' i.e., ArachnoidOptic Nerve Meningioma :?These are invasive tumoursarising from the arachnoidal villi.Meningiomas invading the orbit are of two types :a) Primary intraorbitalmeningiomasThese are also known as 'optic nerve sheath meningiomas'.These produce early visual loss associated with limitation of ocular movements, optic disc oedema or atrophy, and a slowly progressive unilateral proptosis.b) Secondary orbital meningiomasThese intracranial meningiomas, secondarily invade the orbit, either arise from the sphenoid bone or involve it en route to the orbit.Orbital invasion may occur through: floor of anterior cranial fossa, superior orbital fissure and optic canal.Meningioma affecting the greater and lesser wings of sphenoid and taking origin in the region of pterion, is the most common variety affecting the orbit secondarily.