Anatomy of the orbit Prof. Pia C Sundgren MD, PhD Department of Diagnostic Radiology, Clinical Sciences, Lund University, Sweden Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lay-out • brief overview of the basic anatomy of the orbit and its structures • the orbit is a complicated structure due to its embryological composition • high number of entities, and diseases due to its composition of ectoderm, surface ectoderm and mesoderm Recommend you to read for more details Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 3 x 3 Imaging technique 3 layers: - neuroectoderm (retina, iris, optic nerve) - surface ectoderm (lens) • CT and / or MR - mesoderm (vascular structures, sclera, choroid) •IOM plane 3 spaces: - pre-septal •thin slices extraconal - post-septal • axial and coronal projections intraconal • CT: soft tissue and bone windows 3 motor nerves: - occulomotor (III) • MR: T1 pre and post, T2, STIR, fat suppression, DWI (?) - trochlear (IV) - abducens (VI) Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Superior orbital fissure • cranial nerves (CN) III, IV, and VI • lacrimal nerve • frontal nerve • nasociliary nerve • orbital branch of middle meningeal artery • recurrent branch of lacrimal artery • superior orbital vein • superior ophthalmic vein Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Roof Mnemonic of the order in which the nerves frontal bone lesser wing of the sphenoid bone passing through the Sup. orbital fissure Floor ”Lazy French tarts sit naked in anticipation” maxilla zygomatic bone Lacrimal nerve (branch of CN V1) Medial wall Frontal nerve (branch of CN V1) ethmoid bone (lamina papyracea) Trochlear nerve (CN IV) lacrimal bone Superior division of the oculomotor nerve (CN III) maxilla Nascociliary nerve (branch of the CN V1) Lateral wall Inferior division of the oculomotor nerve (CN III) greater wing of the sphenoid bone Abducens nerve ( CN VI) zygomatic bone Courtesy Dr C Romanovski Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Orbital fissures and optic canal Inferior orbital fissure Superior orbital fissure: • infraorbital nerve lesser and greater wing of the sphenoid bone • zygomatic nerve • parasympathetics to Inferior orbital fissure: lacrimal gland greater wing of sphenoid • infraorbital artery the maxilla and palatine bone • infraorbital vein Optic canal: • inferior ophthalmic vein at the apex of the orbit branch to pterygoid plexus in the sphenoid bone Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Infraorbital sulcus and foramen The infraorbital sulcus (SIO) crosses the floor of the orbit and carries • infraorbital artery • infraorbital vein • infraorbital nerve from the inferior orbital fissure to the infraorbital foramen NOTE this is a route of spread for infection or maxillary tumors to the orbit and the skull base Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Optic canal Annulus of Zinn • optic nerve • ophthalmic artery • central retinal vein • dural sheath Calcifications of optic nerve www.clinicalgate.com Courtesy Dr A.I Ranchod, SA Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Optic nerve • cranial nerve II • transmits visual information from the retina to the brain optic n. glioma • composed of retinal ganglion cell axons and support cells optic n. meningioma Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 - preseptal “septum” - postseptal intraconal preseptal ”Septum” extraconal soft tissue/edema - med.palpebral lig. “retrobulbar space” - clinical term Courtesy M Annertz/Lund Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Mnemonic intraconal lesions of the orbita Chemosis of the eye ”Mel met Rita mending hems on poor Charlies grave” swelling of the tissue that lines the eyelids and surface of the eye (conjunctiva) Melanoma Meningeoma pseudotumor Episcleral infiltration Metastasis Hemangioma cellulitis Retinoblastoma Optic glioma Graves disease Preseptal infiltration Courtesy Dr P Maly, Malmoe Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Postseptal extraconal Postseptal intraconal Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Scleritis Buphthalmos and coloboma chronic, painful, inflammatory disease characterized by edema and cellular infiltration of the scleral and episcleral Buphthalmos enlargement of the globe due to tissues (outermost coat of the eye) increased intraocular pressure choroid lens anterior chamber • secondary to obstruction of the Schlemm canal • isolated / associated - Sturge Weber -NF type 1 - cobblestone lissencephaly sclera retina Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Cryptophthalmos A rare congenital anomaly in which the skin is continuous over the eyeball, with absence of eyelids. Eye might be normal or abnormal. Courtesy Dr A.I Ranchod, SA Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Retinal detachment occurs when the intraretinal space persists Courtesy Dr. S Andronikou, SA Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Buphthalmos and coloboma Coloboma congenital fissures in the globe due to incomplete closure of the embryonic optic fissure 0.5 to 0.7 per 10,000 births iris coloboma: defect in anterior portion of the embryonic fissure cleft in the iris pigment epithelium retinochoroidal coloboma: arise from the wall of the globe optic nerve coloboma: insertion of the optic disc Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Retinoblastoma Clinical findings • leukoaria (white pupillary reflex) “cat eye reflex” due to replacement of vitreous humor by a white mass www.retinoblastoma.com • reduced vision, eye pain, strabismus Courtesy Dr A Rossi, IT Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Staphyloma Persistent hyperplastic primary vitreous protrusion of the uveal tissue through a thinning of the sclera - weak point in the eyeball severe axial myopia, more common posteriorly anteriorly more common after infection or trauma M Tsatsos and T Eke Eye (2007) 21, 857–858 Courtesy Dr A.I Ranchod, SA Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Bulb laceration Action of the extra-ocular muscles Muscle Action Cranial Nerve Inf. rectus depresses, turns medially III Inf. oblique elevates turns laterally III Sup. obligue depresses, turns laterally IV (n. trochlearis) Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Extra ocular muscles • develop in situ • input from respective cranial nerve (III, IV,VI) 1 month gestation • fully developed at 6 months gestation Thyroid ophthalmopathy www.pinterest.com Annulus of Zinn m. rectus inferior > med >sup > lat a fibrous ring formed by the common origin of the 4 rectus muscles Lund University / Faculty of Medicine