Orbit and optic nerve

Topic Completed: 1 February 2014

Minor changes: 18 February 2020

Copyright: 2004-2020, PathologyOutlines.com, Inc.

PubMed Search: Orbit [title] optic nerve

Nat Pernick, M.D.
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Page views in 2020 to date: 196
Cite this page: Pernick N. Orbit and optic nerve: general. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/eyeorbitgeneral.html. Accessed May 28th, 2020.
Definition / general
  • Orbit contains globe and its fibrous covering (Tenon capsule), lacrimal gland, optic nerve and its meningeal covering, extraocular muscles, cartilaginous trochlea, blood vessels and delicate fibroadipose connective tissue
  • Floor of orbit is roof of maxillary sinus
  • Medial wall of orbit (lamina papyracea) separates orbit from ethmoidal sinuses
  • Proptosis: forward displacement of eyeball (or other organs), due to any disease that increases orbital contents, since orbit is closed medially, laterally and posteriorly
  • Exophthalmos: abnormal protrusion of eyeball
    • Common symptom of orbital disease, although often due to thyroid disease and not biopsied
    • Other common causes of exophthalmos are mucocele from paranasal sinus, hemangioma, inflammatory pseudotumor
  • Optic nerve:
    • Surrounded by meninges; part of central nervous system
    • Not usually biopsied
    • Often has psammoma bodies or drusen (calcified acellular globular concretions of nerve fibers)
    • Site of convergence of one million axons from retinal nerve fiber layer
    • Nerve head accounts for physiologic blind spot in normal visual field
    • Receives blood supply from branches of ophthalmic artery
    • Surrounded on both sides by short posterior ciliary arteries
  • Lamina cribrosa:
    • Site of myelination of optic nerve axons
    • Highlighted with Luxol fast blue or other myelin stains
  • Trochlea:
    • Arc shaped structure through which tendon of superior oblique muscle passes before insertion upon eyeball
    • The only cartilaginous structure in normal orbit
  • Tumors should be reported using formats published for their counterparts elsewhere in body
  • Drainage through submandibular, parotid and cervical lymph nodes through vascular anastomosis
Radiology images

AFIP images

Normal eye and orbital contents
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MR #1 (T1 weighted)

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MR #2 (T2 weighted)

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MR #3 (T1 weighted) shows coronal section
of orbital contents posterior to globe


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Optic nerve

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Extraocular muscles in orbit

Microscopic (histologic) images

AFIP images
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Intraocular and orbital portions of optic nerve

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Cross section of optic nerve parenchyma and meninges

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Optic nerve and fovea centralis

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