1. W. Abraham White, MD Assistant Professor, KUMC Chief of Ophthalmology, Kansas City VAMC

2.  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

3.  Osteology  Blood supply  Extraocular muscles  Nerves  Putting it all together

4.  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.

5.  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/

6.  Medial Wall Fractures  Transnasal Orbital Decompression  Orbital structures can be inadvertently damaged during FESS procedures

7.  2 Components  Frontal Bone  Lesser wing of sphenoid  Separates Orbit from Brain

8.  Orbital roof fracture  Access point for excision of orbital apex tumors

9.  2 components  Zygomatic Bone  Greater wing of the Sphenoid  Relatively strong, harder to fracture  http://www.slideshare.net/fernferretie/the-orbit

10.  Lateral wall fractures relatively rare  Fracture indicative of significant force  Bone can be removed/reflected to allow access to deeper structures

11.  2 components  Zygomatic Bone  Maxilla  Barrier between the maxillary sinus and orbit

12.  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

13. https://quizlet.com/96898905/orbit-flash-cards/

14. https://quizlet.com/14750275/the-orbit-flash-cards/

15.  No lymphatic system is known  One reason why facial trauma commonly produces significant periorbital swelling

16.  4 Rectus Muscles  2 Oblique Muscles  Levator Palpebrae Superioris

17.  Elevation  Incyclotorsion  Adduction  https://droualb.faculty.mjc.edu/Lecture%20Notes/Unit%203/muscles%20with%20figures.htm

18.  Depression  Excyclotorsion  Adduction

19.  Abduction

20.  Adduction

21.  Incyclotorsion  Depression  Abduction

22.  Excyclotorsion  Elevation  Abduction

23.  Elevates the upper eyelid  Loss of function causes ptosis  http://www.slideshare.net/TheSlaps/dr-b-ch-10lecturepresentation

24.  Optic Nerve (CN II)  Oculomotor Nerve (CN III)  Trochlear Nerve (CN IV)  Ophthalmic Nerve (CN V1)  Maxillary Nerve (CN V2)  Abducens Nerve (CN VI)

25.  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)

26.  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

27.  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

28.  Superior most branch of CN V, also known as V1  Sensory innervation to the upper face and eye

29.  Middle branch of CN V, also known as V2  Travels through the infraorbital canal  Provides sensation to the midface  Often damaged in blowout fractures

30.  Innervates the lateral rectus muscle  May be damaged in trauma or stroke  Lesion causes horizontal diplopia

31.  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