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Orbital volume and dimensions: = 30 cc, 35(Height) x 45(Width) x 45 mm(medial wall depth), globe 25 x 25 mm
Bones: (F)rontal, (M)axillary,(Z)ygomatic, (L)acrimal, (E)thmoid, (P)alatine, (S)phenoid
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- Bones
- Frontal
- Lesser wing of sphenoid
- Cotnents
- lacrimal gland fossa
- trochlea 4mm posterior to margin for superior oblique tendon
- supraobital notch/foramen
- Clincal Correlations
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- Bones
- Maxillary
- Lacrimal
- Ethmoid - thinest
- Sphenoid
- Contents
- lacrimal sac fossa
- cribiform plate is medial to anterior orbit at the level of fronto-ethmoidal suture
- Clincal Correlations
- Nasoclacrimal duct obstructions./tumors/DCRs
- Medial wall fractures
- subperisteal abscess
- Orbital cellulitis/proptosis from ethmodial extension
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- Bones
- Maxillary- second thinnest, thins posteriorly
- Zygoma
- Palatine
- Conents
- infraorbital foramen
- inferior oblique origin
- slopes 20 degrees down
- suspensory ligament of eyeball,
- Clincal Correlations
- subperiosteal abscess
- blow-out fracturs
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- Bones
- Zygomatic bone
- Greater wing of sphenoid
- Contents
- lateral orbital tubercle is 11mm below F-Z suture,
- serves as attachment of check ligament of lateral rectus
- Clincal Correlations
- Tripod fractures
- Ruptured globes
- Lateral tarsal strips
- adjacent to middle cranial fossa, temporal fossa, and pterygopalatine fossa
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- The medial orbital walls are nearly parrallel and are 25 mm apart
- The orbit is widest not at its entrance, but 1 cm from the orbital rim
- Holes & Fissures
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| Fissures |
Holes/Notches/Canals |
Superior orbital fissure (SOF):
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22 mm long
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separates greater wing of spenoid from lesser wing of sphenoid
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transmits third, fourth, sixth and V1 AND SYMPATHETIC FIBERS
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lateral rectus origin separates into superior and inferior divisions
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Superior division transmits lacrimal, frontal and trochlear nerves
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Inferior division transmits superior and inferior divisions of CN III, nasociliary branch of CN V, CN IV, superior ophthalmic vein, and sympathetic nerve plexus
Venous system: supeior ophthalmic vein
Inferior orbital fissure (IOF )
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located between lateral orbital wall and the orbital floor
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Transmits V 2 ( maxillary) , pterygoid nerves nerve arising from pterygopalatine ganglion
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infraorbital nerve (a branch of V 2 ) enters the infraobital groove and infraorbital canal for sensation to lower eyelid, cheek, upper lid, upper teeth
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Venous system inferior ophthalmic vein
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Nasolacrimal canal
Supraorbital foramen/notch:
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transmits blood vessels
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supraorbital nerve
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Anterior/posterior ethmoidal foramen: transmits ethmoidal blood vessels and nerve
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Zygomatic foramen: transmits zygomaticofrontal and zygomaticotemporal nerves, zygomatic artery
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Nasolacrimal duct (NLD): exits into inferior meatus
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Infraorbital canal: transmits infraorbital nerve (V 2 )
Ethmoidal foramina
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anterior ethmodial artery
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posterior ethmoidal artery
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allows infections and neoplasms to enter to orbit from the sinuses
Optic Canal
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8-10 mm long
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located within the less wing of sphenoid
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separated from SOF by OTIC STRUT
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Transmits. Ophthamic nerve, ophthalmic artery, sympathtic nerves
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