Bony orbit

Boundaries and contents of the orbital cavity

1. Thebonyorbit&contents
1GRN
All the information, including the images and pics
collected from various sources is strictly for
teaching and helping the students in learning.
Dr. G. RAVINDRANATH MBBS; MS
PROFESSOR OF ANATOMY,
NRI INSTITUTE OF MEDICAL SCIENCES

2. 2GRN
Learningobjectives
1.Describetheboundariesoforbitalcavity
2.Namethecontentsoftheorbitalcavity

3. Thebonyorbits
•Skeletalcavitieslocated
oneithersideoftherootof
thenose.
•Shape-quadrilateral
pyramidwithitsbaseatthe
orbitalopening&apex
alongaposteromedially
directedaxisattheoptic
canal
•Eachorbithasaroof,
floor,medialandlateral
walls.
3GRN

4. 4GRN

5. Thebonyorbits
•Themedialwallslie
approximately25mmapartin
adultsandareparallel.
•Theanglebetweenthe
medialandlateralwallsis
about45°.
•Eyeballislocatedanteriorlywithintheorbit&thusoccupies
onlyonefifthofthevolumeoftheorbit,theremainderofthe
cavityisfilledwithvesselsandnervesthatarecontainedwithin
andsupportedbyorbitalfatandconnectivetissue.
5GRN

6. Theroofoftheorbit
Formedby:
1.Orbitalplateofthefrontal
bone,
2.Lesserwingofthesphenoid,
Anteromediallyitdisplaysasmall
trochlearfovea,wherethe
cartilaginoustrochlea(pulley)for
superiorobliqueisattached.
Anterolaterallythereisashallow
lacrimalfossawhichhousesthe
orbitalpartofthelacrimalgland. Roofseparatestheorbitalcontents
andthebrainintheanteriorcranial
fossa.
,
GRN 6

7. Theroofoftheorbit
•Theroofslopestowardsthe
apex,joiningthelesserwing
ofthesphenoid.which
completestheroof.
•Theopticcanalliesbetween
therootsofthelesserwing
andisboundedmediallyby
thebodyofthesphenoid.
•Thelateralwallandroofare
separatedposteriorlybythe
superiororbitalfissure
7GRN

8. Themedialwalloftheorbit
Formedby:
1.Frontalprocessofthe
maxilla
2.Lacrimalbone
3.Paperthin,rectangular
orbitalplate(lamina
papyracea)oftheethmoid
bone
4.Bodyofthesphenoid
8GRN

9. Themedialwalloftheorbit
Theorbitalplateoftheethmoidboneseparates
themiddleandposteriorethmoidalaircells
fromtheorbit.
Posteriorly,itarticulateswith
thebodyofthesphenoid,which
formsthemedialwallofthe
orbituptotheapex.
Anteriorlythemedialwallis
formedbythelacrimalbone
whichcontainsafossaforthe
nasolacrimalsac
9GRN

10. Themedialwalloftheorbit
Fossaforthenasolacrimalsac
islimitedinfrontbytheanterior
lacrimalcrestonthefrontal
processofthemaxillaand
behindbytheposterior
lacrimalcrestofthelacrimal
bone(towhichthelacrimalpart
oforbicularisoculiandlacrimal
fasciaisattached).
10GRN

11. Themedialwalloftheorbit
Superiorly,medialwallarticulates
withthemedialedgeoftheorbital
plateofthefrontalboneatasuture
whichisinterruptedbyanteriorand
posteriorethmoidalforamina.
Adescendingprocessofthelacrimal
boneatthelowerendofthe
posteriorlacrimalcrestcontributes
totheformationoftheupperpartof
thenasolacrimalcanal,whichis
completedbythemaxilla.
11GRN

12. Theflooroftheorbit
Formedby
1.orbitalplateofthemaxilla
2.orbitalprocessofthepalatine
bone.
Theflooristhinandlargelyroofs
themaxillarysinus.
Anteriorlythefloorcurvesand
continuesintothelateralwall,but
posteriorlyitisseparatedfromthe
lateralwallbytheinferiororbital
fissure.
12GRN

13. Theflooroftheorbit
Themediallipoftheinferiororbital
fissure,isnotchedbytheinfraorbital
groovewhichpassesforwardsand
sinksintothefloortobecomethe
infraorbitalcanal,whichopensonthe
faceattheinfraorbitalforamen.
Proportionallymoreorbitalfractures
involvethefloor,particularlyinthe
regionoftheinfraorbitalgroove.
The classic‘blowout fracture’leaves
theorbitalrimintactandtypically
entrapssofttissuestructures,leading
todiplopia,impairedocularmotility
andenophthalmos.
Theinferiororbitalfissureconnectsthe
orbitposteriorlytothepterygopalatine
fossa,andmoreanteriorlytothe
GRinNfratemporalfossa. 13

14. Thelateralwalloftheorbit
Formedby:
1.Frontalprocessofthe
zygomaticbone(anteriorly),
2.Orbitalsurfaceofthegreater
wingofsphenoid(posteriorly)
Thebonesmeetatthe
sphenozygomaticsuture.
Thelateralwallisthethickestwall
oftheorbit.
14GRN

15. Thelateralwalloftheorbit
Thelateralwalliscontinuouswiththe
flooranteriorly,butposteriorlyitis
separatedfromthefloorbythe
inferiororbitalfissure.
Similarly,thelateralwallandroofare
continuousanteriorlybutare
separatedposteriorlybythesuperior
orbitalfissure,whichliesbetweenthe
greaterwing(below)andlesserwing
(above)ofthesphenoid,and
communicateswiththemiddlecranial
fossa.
15GRN

16. Thelateralwalloftheorbit
Laterally,thelateralwallseparatesthe
orbitfromthetemporalandthe
infratemporalfossa.
Thezygomatic(lateral)surfaceofthe
lateralwallshowstheopeningsoftwo
minutecanals:
1.Zygomaticofacial(nearthejunction
ofthefloorandlateralwall)and
2.Zygomaticotemporal(ataslightly
higherlevelthantheformer).
16GRN

17. Theorbitaltubercleof
Whitnall,towhichthelateral
palpebralligament,
thecheckligamentoflateral
rectusandtheaponeurosis
oflevatorpalpebraeareall
attached,liesjustinsidethe
midpointofthelateral
orbitalmargin.
17GRN
Thelateralwalloftheorbit

18. 18GRN

19. 19GRN
Note the position of the common annular tendon(CAT) in the orbit

20. 20GRN

21. 21GRN
Cavernous sinus

22. IDENTIFY……
22GRN

23. Contentsoftheorbit
Theorbitcontainsthe:
23GRN
3.Optic,oculomotor,trochlearandabducentnerves,
4.Branchesoftheophthalmicandmaxillarydivisionsof
thetrigeminalnerve;
5.Ciliaryparasympatheticganglion;
6.Ophthalmicvessels;
7.Lacrimalapparatus.
1.Eyeball
2.Extraocularmuscles;

24. THANKYOU
24GRN