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Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
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
Lay-out
• brief overview of the basic anatomy of the orbitand 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 andmesoderm
Recommend you to read for more details
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
3 layers: - neuroectoderm (retina, iris, optic nerve) - surface ectoderm (lens)- mesoderm (vascular structures, sclera, choroid)
3 spaces: - pre-septal
extraconal
- post-septal
intraconal
3 motor nerves: - occulomotor (III)
- trochlear (IV)
- abducens (VI)
3 x 3
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
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
• CT and / or MR
• IOM plane
• thin slices
• axial and coronal projections
• CT: soft tissue and bone windows
• MR: T1 pre and post, T2, STIR, fat suppression, DWI (?)
Imaging technique
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
Rooffrontal bonelesser wing of the sphenoid bone
Floormaxillazygomatic bone
Medial wallethmoid bone (lamina papyracea)lacrimal bonemaxilla
Lateral wallgreater wing of the sphenoid bonezygomatic bone
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Orbital fissures and optic canal
Superior orbital fissure: lesser and greater wingof the sphenoid bone
Inferior orbital fissure: greater wing of sphenoid the maxilla and palatine bone
Optic canal: at the apex of the orbit in the sphenoid bone
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
Mnemonic of the order in which the nervespassing through the Sup. orbital fissure
”Lazy French tarts sit naked in anticipation”
Lacrimal nerve (branch of CN V1)Frontal nerve (branch of CN V1)Trochlear nerve (CN IV)Superior division of the oculomotor nerve (CN III)Nascociliary nerve (branch of the CN V1)Inferior division of the oculomotor nerve (CN III)Abducens nerve ( CN VI)
Courtesy Dr C Romanovski
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Inferior orbital fissure
• infraorbital nerve
• zygomatic nerve
• parasympathetics to lacrimal gland
• infraorbital artery
• infraorbital vein
• inferior ophthalmic veinbranch to pterygoid plexus
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
The infraorbital sulcus (SIO) crosses the floor of theorbit 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
Infraorbital sulcus and foramen
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Optic canal
• optic nerve
• ophthalmic artery
• central retinal vein
• dural sheath
www.clinicalgate.com
Annulus of Zinn
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
• composed of retinal ganglion cell axons and support cells
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
Courtesy Dr A.I Ranchod, SA
Calcifications of optic nerve
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
optic n. glioma
optic n. meningioma
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
- preseptal
- postseptal intraconal extraconal
“septum”
“retrobulbar space”- clinical term
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Mnemonic intraconal lesions of the orbita
”Mel met Rita mending hems on poor Charlies grave”
Melanoma Meningeoma pseudotumor
Metastasis Hemangioma cellulitis
Retinoblastoma Optic glioma Graves disease
Courtesy Dr P Maly, Malmoe
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
preseptalsoft tissue/edema
”Septum”- med.palpebral lig.
Courtesy M Annertz/Lund
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Episcleral infiltration
Preseptal infiltration
Chemosis of the eyeswelling of the tissue that lines the eyelids and surface of the eye (conjunctiva)
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
lens anterior chamberchoroid
sclera retina
Scleritischronic, painful, inflammatory diseasecharacterized by edema and cellularinfiltration of the scleral and episcleraltissues (outermost coat of the eye)
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 benormal or abnormal.
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Retinal detachment
occurs when the intraretinal space persists
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Buphthalmos enlargement of the globe due toincreased intraocular pressure
• secondary to obstruction of the Schlemm canal
• isolated / associated - Sturge Weber - NF type 1- cobblestone lissencephaly
Buphthalmos and coloboma
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Courtesy Dr A.I Ranchod, SA
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Courtesy Dr. S Andronikou, SA
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
Courtesy Dr A Rossi, IT
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
protrusion of the uveal tissue through a thinningof the sclera - weak point in the eyeball
Staphyloma
severe axial myopia, more common posteriorlyanteriorly more common after infection or trauma
M Tsatsos and T Eke Eye (2007) 21, 857–858
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
• reduced vision, eye pain, strabismuswww.retinoblastoma.com
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Persistent hyperplastic primary vitreous
Courtesy Dr A.I Ranchod, SA
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Bulb laceration
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
www.pinterest.com
Annulus of Zinna fibrous ring formed by the common origin of the 4 rectus muscles
Extra ocular muscles
• develop in situ
• input from respective cranial nerve (III, IV,VI) 1 month gestation
• fully developed at 6 months gestation
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Muscle Action Cranial Nerve
Lat. rectus moves eye laterally VI ( n.abducens)
Med. rectus moves eye medially III (n. oculomotorius)
Sup. rectus elevate, turns it medially III
Action of the extra-ocular muscles
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Muscle Action Cranial Nerve
Inf. rectus depresses, turns medially III
Inf. oblique elevates turns laterally III
Sup. obligue depresses, turns laterally IV (n. trochlearis)
Action of the extra-ocular muscles
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Thyroid ophthalmopathy
m. rectus inferior > med >sup > lat
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
The major nerves
Cranial nerves – motor III oculomotor nIV trochlear nVI abducens n
II optic nerve
Cranial - sensory nervesV trigeminal n – ophthalmic n V1 (the upper eyelid, the conjunctiva and cornea of the eye) and its branches
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
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Ophthalmic nerve
nasociliary nervefrontal nervelacrimal nerve
branches
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
The ophthalmic artery enters the orbit on the inferolateral side of the optic nerve and gives off the central retinal arteryand posterior ciliary arteries near the orbital apex
The ophthalmic artery
http://www.retinareference.com/anatomy/first branch of the a. int car.
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Involvement of the ophthalmic artery in giant cell arteritis
Copyright © 2016 British Society for Rheumatology
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Kumar JB et al EyeNet Magazine May 2015
The orbital veins
NOTE the superior ophthalmic vein is a communicationbetween facial vein and cavernous sinus “Danger Zone”
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Ophthamology.standford.edu
T1 weighted, without fat suppression, showing bilateral enlarged superior ophthalmic veins in carotid cavernous stula
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Orbital phlebograhy
showing left-sided venousfistula
Courtesy Dr. P Maly, Malmoe
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018
Take home message
complicated anatomy and embryology
high number of possible diseases
For correct diagnosis
important to differentiate between the preseptal andpostseptal space
important to differentiate between extraconal andintraconal
Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018PC Sundgren, Spine Infect… ASSR’ 12
Thank you
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