HeadandNeckTheOrbit

Prof.Dr.MohamedElfiky

ProfessorofAnatomyandembryology

Extra-ocularMuscles

1-Levator palpebrae

superioris

2-Superiorrectus.

3-Lateralrectus.

4-Inferiorrectus.

5-Medialrectus.

6-Superioroblique.

7-Inferioroblique.

LevatorPalpabraeSuperioris

1- LevatorPalpabraeSuperioris

.Origin:Fromtheroofoftheorbitinfrontoftheopticcanalinsertion:Formsthreelamellaewhichareinsertedinto:

(1)Theskinoftheuppereyelid.(2)Thesuperiortarsus.(3)Superiorfornixoftheconjunctiva.

Nervesupply:Oculomotornerve.Actions:Elevationoftheupper

eyelid.

Ptosis

SuperiorRectus

LateralRectus

InferiorRectus

MedialRectus

FourRectiSuperior,Inferior,MedialandLateral

AnnulusRingofZinn

Origin:Fromthecommontendinousring(ringofZinn)whichsurroundstheopticcanalInsertion:Therectiareinsertedintothesclerainfrontoftheequatoroftheeyeball.Theaveragedistancesfromthecorneaare:

(a) Superiorrectus:7.7mm.(b) (b)Lateralrectus:6.9mm.(c)Inferiorrectus:6.5mm.(d)Medialrectus:5.5mm.

SuperiorOblique

InferiorOblique

TheTwoObliqueMusclesSuperiorandInferiorOblique

SuperiorobliqueOrigin:Fromthebodyofsphenoidsuperomedialtotheopticforamen.Insertion: Passesforwardsalongthemedialwalloftheorbit.Endsinaslendertendon,whichpassesthroughafibrocartilaginousbully(trochlea)attachedtothetrochlearfossaofthefrontalbone.Thetendonthenpassesdownwards,backwardsandlaterallytobeinsertedintothelateralsurfaceofthesclerabehindtheequator.

Inferioroblique

Origin:Fromtheflooroftheorbitlateraltothelacrimalnotch.Insertion:PasseslaterallybelowtheinferiorrectusandthendeeptothelateralInsertedintothelateralsurfaceofthesclerabehindtheequator.

NerveSupplyoftheExtra-ocularMuscles(SO4 LR6)3

Note:Alltheextrinsicmusclesoftheeyeballaresuppliedbytheoculomotor nerveexcept:(1)Lateralrectus:bytheabducent.

(2)Superioroblique:bythetrochlear.(SO4LR6)3

ActionoftheExtra-ocularMuscles(1)Levatorpalpebraesuprioris:Elevationoftheuppereyelid.

(2)Superiorrectus:(a)Elevation;(b)Adduction;(c)Intortion.

(3)Inferiorrectus:(a)Depression;(b)Adduction;(c)Extorsion

(4)Medialrectus:Adduction.

(5)Lateralrectus:Abduction

(6)Superioroblique:(a)Depression;(b)Abduction;(c)Intortion.

(7)Inferioroblique:(a)Elevation;(b)Abduction;(c)Extorsion.

12o’clock

SuperiorRectus

InferiorRectus

SuperiorObliqueInferiorOblique

MedialRectus

LateralRectus

ThePrimaryPosition

SuperiorRectusInferiorRectusSuperiorObliqueInferiorObliqueMedialRectus

LateralRectusThePrimaryPosition

12o’clock

ActionsoftheExtra-ocularMuscles

Squint

1- OphthalmicArtery

Origin:ItisabranchoftheinternalcarotidarteryCourseandrelations: Enterstheorbitthroughtheopticcanal.

Branches:

(1)Centralarteryoftheretina:mostimportantbranch,itpiercestheopticnerveandrunsthroughit

toreachtheretina.

(2)Lacrimalartery:tothelacrimalgland.

(3)Muscularbranches:totheorbitalmuscles.

(4)Longandshortposteriorciliaryarteries:supplytheeyeball.

(5)Anteriorandposteriorethmoidalarteries:accompanytheanteriorand

teriorethmoidalnerves.

(6)Supraorbital:accompaniesthecorrespondingnervetothescalp

(7)Supratrochlear:oneofthetwoterminalbranches,accompaniestheupratrochlearnerve.

(8)Dorsalnasal:istheotherterminalbranch,passesbelowthetrochleatosupplythenose

InternalCarotidArtery

OphthalmicArtery

OpticCanal

OpticNerve

8-SupratrochlearArtery(terminalbranch)7-DorsalNasalArtery(terminalbranch)

1- OphthalmicArtery

4-Supraorbital

2- LacrimalArtery

3- PosteriorCiliary Arteries

6- AnteriorEthmoidal Artery

5- PosteriorEthmoidal Artery

1- CentralArteryoftheretina

1- OphthalmicArtery

SuperiorOphthalmicVein

InferiorOphthalmicVein

PterygoidPlexusofVeins

AnteriorFacialVein

2- OphthalmicVeins

Nervesoftheorbit

(1) Opticnerve:it isthe1stcranialnerve.Itpassthroughtheoptiv canalanditthenerveofvision.

(2)Oculomotor nerve :

§ Comesoutofthemidbrain.§ Entersthecavernoussinus

§ Dividesintheanteriorpartofthesinusintosuperiorandinferiordivisions,

Distribution:(1)Thesuperiordivision:supplies2muscles:

(a)Superiorrectus. (b)Levator palpebrae superioris.(2)Theinferiordivision:supplies3muscles:

(a)Medialrectus.(b)Inferiorrectus.(c)Inferior obique.

(3)MotorroottotheCiliary ganglion:Carriesparasympatheticfiberstosupply2intraocularmuscles:(a)Ciliary muscle:foraccoummodation.(b)Sphincterpupillae muscle:constrictsthepupil.

Trochlearnerve:Origin:fromthemidbrainattheleveloftheinferiorcolliculus.• Course:Entersthecavernousandintertheorbitthrough

suporbitalfissure• Distribution:Suppliesthesuperiorobliquemuscle.

Abducentnerve:Origin:fromtheponsCourse:RunsforwardsinthefloorofthecavernoussinusEnterstheorbitthroughthesuperiororbitalfissure.Distributions:Suppliesthelateralrectusmusclethroughitsocularsurface.

(5)Ophthalmicdivisionoftrigeminal

Origin:Fromtheconvexanteriormarginofthetrigeminalganglion.Course:· runsforwardsinthelateralwallofthecavernoussinus· Dividesinthesinusinto3branchesBranches:

(A)Frontal.(B)Lacrimal.(C)NasociliaryThethreebranchesentertheorbitthroughthesuperiororbitalfissure.

FrontalnerveBranches:(1)Supratrochlearnerve:(2)Supraorbitalnerve:

LacrimalnerveBranches:· Glandularbranches:tothelacrimalgland(sensory).· Palpebralbranch:totheskinofuppereyelid.

NasociliarynerveBranches:(1)Communicatingbranchtotheciliaryganglion;(2)Twoorthreelongciliarynerves:Containssympatheticfibersforthedilatorpubillae(3)Posteriorethmoidalnerve:(4)Infratrochlear:(5)Anteriorethmoidalnerve:

Ciliaryganglion

Site:Betweentheopticnerveandthetendonofthelateralrectusmuscle.

Roots:(1)Parasympathetic(Motor):fromthenervetoinferioroblique(branchof

oculomotor).Itrelaysintheganglion.(2)Sensoryroot:comesfromthenasociliary nerve.Itcontainssensoryfibersfrontthe

eyeball.Thefibersdonotrelayintheganglion,(3)Sympatheticroot:isabranchfromthesympatheticplexus,aroundtheinternal

carotid(passeswithoutrelay).Branches:Shortciliary nerves :

(a)Sensoryfibers:fromtheeyeball.(b)Sympatheticfibers:forthebloodvesselsof'theeyeball.(c)Parasympatheticpostaganglionic fibers:tothesphincterpupillae andciliarymucles.

Ciliaryganglion

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