anatomy

Human Eye AnatomyBasic Human AnatomyCPU-College of Medicine1st Year, Second Semester

Jeffrey J. Gumban, EyeMD

Part I Embyology & Ocular Adnexae

Course OutlinePart IEmbryology & Ocular AdnexaePart IIConjunctiva, Sclera & CorneaPart IIILens, Ciliary Body & VitreousPart IVRetina, Optic Nerves & Pathways


Embryology


Orbital Anatomy7 bones30 cc (35 mm width x 40 mm height)25-30 mm orbital optic nerveRimZygomaticMaxillaryFrontalFloor (3 bones)Zygomatic, maxillary and palatineMedial wall (4 bones)Sphenoid, lacrimal, ethmoid, maxillaryRoof ( 2 bones)Frontal, sphenoidLateral wall (2 bones)Zygomatic, sphenoid (greater wing)


Orbital Anatomy (cont.)Inferior orbital fissureBound by sphenoid, maxillary and palatine bonesTransmits V2 which exits skull through foramen rotundumAnnulus of ZinnFibrous rings formed by rectus musclesDoes not include IV


Orbital Anatomy (cont.)Optic foramen8-10 mmLocated within lesser wing of sphenoidTransmits optic nerve, ophthalmic a. and sympathetic nerves

Superior orbital fissureBound by greater and lesser sphenoid wingsOutside annulus (luscious French tarts)lacrimal, frontal, IVInside annulus (sit naked in anticipation)III-sup, nasociliary III-inf, VI


Superficial Eyelid LandmarksEyebrowPeaks at 9:00 limbus1 cm above orbital rim in youthFlatter in males, more flared in femalesPalbebral FissureHorizontal 28-30 mmVertical 9-11 mm


Superficial Eyelid LandmarksUpper Eyelid MarginPeaks slightly nasal to the pupilupper limbus in youth1.5 - 2.0 mm below in adultLower Eyelid Margininferior limbusMargin above superior limbus or below inferior limbus termed retraction or scleral show


Superficial Eyelid LandmarksLateral commissure5 mm nasal to lateral rim2 mm above medial in males4 mm above medial in femalesMedial commissure


Superficial Eyelid LandmarksUpper Eyelid Crease7 - 8 mm above the margin in males9 - 10 mm above the margin in femalesLower Eyelid Creasepoorly defined5 mm below the margin


Eyelid AnatomyDivided into anterior and posterior lamellaAnterior LamellaSkinOrbicularisPosterior LamellaConjunctivaTarsus


Eyelid Anatomy (cont.)skin and subcutaneous tissueorbicularis muscle and submuscular fibroadipose tissueorbital septumpreaponeurotic fatretractorstarsus and conjunctiva


Skin and Subcutaneous FasciaThinnest of the body (~ 1mm) - thinnest mediallyLittle or no subcutaneous fatSubjected to the most movement; stretching and relaxing


Skin and Subcutaneous FasciaUpper eyelid crease9-10 mm in females, 7-8 mm in malesformed by levator attachments to pretarsal skinlower in Asians because septum joins levator at a lower point allowing inferior fat migrationLower eyelid creasemarks the lower edge of tarsusslopes from 5 mm medially to 7 mm laterally


Eyelid ProtractorsOrbicularis oculi - horseshoe-shaped muscleOrbitalPreseptalPretarsal


Orbital OrbicularisVoluntaryAbove - inserts to the anterior supraorbital margin medial to the supraorbital foramen; shares a common insertion with corrugator supercilli Below - inserts to the anterior infraorbital margin medial to infraorbital foramen


Preseptal OrbicularisInvoluntaryLaterally: continuous overlying lateral canthal tendonMedial insertionanteriorly to medial canthal tendonposteriorly (Jones muscle) to the lacrimal diaphragm; upper may also insert on posterior lacrimal crest


Pretarsal OrbicularisFirmly attached to tarsusLateral - gives rise to lateral canthal tendonMedialSuperficial heads form the medial canthal tendon which inserts to the medial orbital marginDeep heads (Horners muscle) insert into the lacrimal bone at posterior lacrimal crestRiolans muscle forms grey line


Medial Orbicularis Attachments


Orbital SeptumOrbital septum + tarsus = middle lamella of the eyelidOriginates at the arcus marginalis (periosteum)Superior - fuses with the levator aponeurosis 2-5 mm (avg. 3.4 mm) above the superior tarsal border


Orbital SeptumInferior - fuses with inferior border of tarsus, separated from capsulopalpebral fascia by postseptal fatLateral - inserts anterior to lateral canthal tendonMedial - inserts on posterior lacrimal crest (i.e, lacrimal sac is outside orbit)


Orbital Fat PadsUpper Eyelidpreaponeuroticnasal - whiter shadeLower Eyelidnasal - whiter shade central temporal


Eyelid Retractors


Retractors of Upper EyelidLevator palpebrae superiorisOriginates at orbital apexHorizontal (40 mm) and vertical (15-20 mm) componentsChanges from horizontal to vertical at Whitnalls ligamentVertical component has two layerslevator aponeurosissuperior tarsal muscle (Mullers)


Retractors of Upper EyelidLevator Aponeurosisforms lateral and medial horns - attach to respective retinaculaeattaches into the pretarsal muscle and skin and anterior lower 1/3 of anterior tarsal surface


Retractors of Upper EyelidSuperior Tarsal Muscle (Mullers)innervated by cervical sympathetic systeminserts at superior tarsal bordermedially attaches to the medial hornHorners syndrome is due to Mullers muscle paralysis


Retractors of Upper Eyelid


Retractors of Lower Eyelidcapsulopalpebral head given off by inferior rectussplits around inferior oblique and reunites as Lockwoods ligamentcapsulopapebral fascia projects anteriorly from Lockwoods ligament and attaches to inferior tarsal border


Retractors of Lower Eyelidinferior tarsal muscle (mullers) terminates 2.5 mm beneath inferior tarsal border


Tarsus Dense irregular connective tissue - not collagenMeibomian glandsorifices located posterior to lashes and grey line30-40 upper20-30 lowerCilia bulbs - on top of tarsus


Lateral Whitnalls Orbital TubercleLateral retinaculumlateral horn of levator aponeurosislateral canthal tendoninferior suspensory Lockwoods ligamentcheck ligament of lateral rectusWhitnalls ligament inserts 10 mm superior to lateral orbital tubercle (NOT on Whitnalls tubercle)


Posterior Lacrimal CrestMedial ocular retinaculuminferior transverse Lockwoods ligamentmedial rectus check ligamentdeep heads of pretarsal musclemedial horn of levator aponeurosisorbital septum


Vascular Supply


Lymphatic Drainage


Sensory Nerve Supply


Basic SecretorsBasic secretorsdecreases with ageno efferent innervation


Mucin SecretorsGoblet Cellsthroughout the conjunctiva, denser nasallyCrypts of Henleupper 1/3 of upper tarsuslower 1/3 of lower tarsusGlands of Manzcircumcorneal ring of the limbal conj.


Aqueous SecretorsGlands of Krausefornix - subconjunctival40 in upper, 6-8 in lowerGlands of Wolfringupper and lower border of tarsus2-5 in upper, 2 in lower


Oil SecretorsMeibomian glandsin the tarsal plates25-40 in upper, 20 in lowerZeisfollicles of eyelashesMollroot of eyelashes


Basic Secretors - Re-cap


Reflex SecretorsLacrimal gland - main (orbital) and palpebral lacrimal glandsexocrine glands efferent parasympathetic innervation hypersecretion


Main (Orbital) Lacrimal Gland20mm x 12mm x 15mm.78 gm4 ligaments firmly hold gland in placeSommerings ligament - periosteum from roofPosterior - inferior ligament of SchwalbeSuperior transverse Whitnalls ligamentLateral horn of levator aponeurosis


Main (Orbital) Lacrimal GlandLacrimal foramen2 to 6 excretory ducts - pierce conjunctiva 5 mm above lateral margin of the tarsus


Palpebral Lacrimal GlandAbout 30 loosely knit lobules each with a secretory duct that empties into a main excretory ductUpper lobules present at lacrimal foramenCan be prolapsed into viewMay have 1 to 2 main excretory ducts


Reflex SecretorsFifth cranial nerve is the reflex, afferent pathway for the main and palpebral lacrimal glandsOther areas that may initiate a response - retina - thalamus - frontal cortex - hypothalamus - basal ganglia - cervical sympathetic ganglia


Reflex SecretorsVII nerve - parasympathetic/efferent pathwayArise in ponsFibers join sensory route of VIIPass through facial nucleusSynapse in sphenopalatine ganglionPost-ganglionic fibers incorporated in zygomatic nerve (V2)Fibers join lacrimal nerve (V1)


Reflex SecretorsVII nerve - parasympathetic/efferent pathway


Reflex SecretorsSympathetic - efferent pathwayFibers arise in the hypothalamusPass to superior cervical ganglionPost-ganglionic fibers : 3 routesSphenopalatine ganglion and zygomatic nerveAccompany the lacrimal arteryWithin the lacrimal nerve


Distributional SystemEyelids distribute tearsregulate evaporationexpel superfluous tears assist in the formation of the precorneal tear film


Excretory SystemUpper and lower canaliculiLacrimal sacNasolacrimal ductPalpebral parts of the orbicularis oculiApprox. 35 mm in length


CanaliculiCanaliculi - 10 mm in length, 2 mm vertical and 8 mm horizontal Diameter - punctum 0.3 mm - ampulla 2 to 3 mm - canaliculi 0.5 mm Lined by stratified squamous epithelium, surrounded by dense connective tissue


Canaliculi90% have common canaliculus - enters posterior and superiorDilation of common canaliculus is the sinus of MaierValve of Rosenmuller at distal end of common canaliculus


Lacrimal Sac and Nasolacrimal DuctLined double layered columnar epitheliumSingle structure ~ 35 mm in lengthCanaliculi 8-10 mmFundus - 4 mmBody - 8 mmDuct - 12 mm


Nasolacrimal DuctMeatal NLD - 5 mm: guarded by Hasners valve Angled slightly lateral and posteriorOpens into the inferior meatusDistance from the entrance of nose to duct is 35 mm (less in infants)


Lacrimal DiaphragmExtension of orbital periosteumsac within a sacInferior and superior preseptal muscles insert into itThinnest at lower end of anterior lacrimal crest


Lacrimal Pump (cont.)


anatomy

Documents

embyology ocular adnexaeskin

inferior orbital fissurebound

optic foramen8

subcutaneous fasciathinnest

subcutaneous fatsubjected

orbital rim

sphenoid greater wingpart

optic nerves pathwayspart