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Published byJohn Thornton Modified over 8 years ago
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W. Abraham White, MD Assistant Professor, KUMC Chief of Ophthalmology, Kansas City VAMC
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No financial interests to disclose The views represented are my own, and do not necessarily represent those of the Federal Government or Department of Veterans Affairs
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Osteology Blood supply Extraocular muscles Nerves Putting it all together
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Pear/cone shaped structure Formed by 7 bones Frontal Zygomatic Maxilla Lacrimal Ethmoid Palatine Sphenoid OpenStax, The Skull. OpenStax CNX. Jun 27, 2013 http://cnx.org/contents/d70fa6d3-5301- 4364-9060-72d7073c2e97@4.
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4 components Orbital process of ethmoid Lacrimal bone Sphenoid body Medial portion of frontal bone Very thin walled Forms barrier between nose and orbit https://quizlet.com/19962294/the-orbit-flash-cards/
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Medial Wall Fractures Transnasal Orbital Decompression Orbital structures can be inadvertently damaged during FESS procedures
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2 Components Frontal Bone Lesser wing of sphenoid Separates Orbit from Brain
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Orbital roof fracture Access point for excision of orbital apex tumors
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2 components Zygomatic Bone Greater wing of the Sphenoid Relatively strong, harder to fracture http://www.slideshare.net/fernferretie/the-orbit
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Lateral wall fractures relatively rare Fracture indicative of significant force Bone can be removed/reflected to allow access to deeper structures
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2 components Zygomatic Bone Maxilla Barrier between the maxillary sinus and orbit
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Orbital blowout fractures Medial portion is thinnest – lamina papyracea Medial wall fracture commonly associated Most common site of entrapment Mostly younger patients “greenstick” phenomenon - trapdoor
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https://quizlet.com/96898905/orbit-flash-cards/
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https://quizlet.com/14750275/the-orbit-flash-cards/
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No lymphatic system is known One reason why facial trauma commonly produces significant periorbital swelling
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4 Rectus Muscles 2 Oblique Muscles Levator Palpebrae Superioris
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Elevation Incyclotorsion Adduction https://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%203/muscles%20with%20figures.htm
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Depression Excyclotorsion Adduction
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Abduction
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Adduction
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Incyclotorsion Depression Abduction
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Excyclotorsion Elevation Abduction
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Elevates the upper eyelid Loss of function causes ptosis http://www.slideshare.net/TheSlaps/dr-b-ch-10lecturepresentation
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Optic Nerve (CN II) Oculomotor Nerve (CN III) Trochlear Nerve (CN IV) Ophthalmic Nerve (CN V1) Maxillary Nerve (CN V2) Abducens Nerve (CN VI)
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Begins in retina Intraocular portion exits through posterior globe (1 mm) Intraorbital segment traverses intraconal space (25 mm) Intracanalicular segment exits the orbit through optic canal (Sphenoid) (~10 mm) Intracranial segment converges with contralateral to form chiasm (10 mm)
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Superior Division – Levator and Superior Rectus Inferior Division – Medial/Inferior Recti, Inferior Oblique, Pupil constrictors (Edinger- Westphal nucleus) Clinical correlation – inferior peribulbar block may not initially reach the superior division, leading to an eye that is persistently elevated. Lesion of complete nerve causes ptosis and an eye that is “down and out”, with dilated pupil
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Innervates Superior Oblique 4 unique features Exits from dorsum of brain Immediately decussates Smallest diameter cranial nerve Longest intracranial course Most commonly injured with head trauma Lesion causes vertical and torsional diplopia
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Superior most branch of CN V, also known as V1 Sensory innervation to the upper face and eye
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Middle branch of CN V, also known as V2 Travels through the infraorbital canal Provides sensation to the midface Often damaged in blowout fractures
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Innervates the lateral rectus muscle May be damaged in trauma or stroke Lesion causes horizontal diplopia
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Intraconal structures Extraconal structures https://www2.aofoundation.org/wps/portal/!ut/p/a0/04_Sj9CPykssy0xPLMnMz0vMAfGjzOKN_A0M3D2 DDbz9_UMMDRyDXQ3dw9wMDAzMjfULsh0VAbWjLW0!/?bone=CMF&segment=Midface&showPage=A& contentUrl=srg/popup/additional_material/92/04-PeriorbitalDissection1.jsp
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