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277 Cards in this Set

  • Front
  • Back
The muscles of the iris are derived from
Neural ectoderm
The pars plana functions to
Restore MPS important to the vitreous
The pars plicata functions to
Make aqueous via active transport
Layers of the irisAnterior border layerStromaAnterior epithelium and dilator musclePosterior pigmented epithelium
Part you seeContains sphincter muscleOne cell layerOne cell layer
The dilator muscle consists of
Radial extensions of the unpigmented anterior epithelium
Longitudinal fibers of the ciliary muscle
Arise from anterior choroids and run to the scleral spur
Circular fibers of the ciliary muscle form a
Sphincter around the edge of the CB behind the iris root
Radial fibers of the ciliary muscle form a
Meshwork between the longitudinal and circular fibers
1st synapse of the light reflex pathway occurs in the
Pretectal nucleus
2nd synapse of the light reflex pathway occurs in the
EW nucleus
3rd synapse of the light reflex pathway occurs in the
Ciliary ganglion
From the ciliary ganglion the signals travel down
Short ciliary nerves to the iris sphincter of both eyes
For eyes to dilate, the lack of light sends a signal to
Lateral geniculate body (synapse)
From the LGB the signal travels to the
Cortex (synapse) and hypothalamus and reticular formation
The final synapse for pupil dilation is in the
Superior cervical ganglion
From the superior cervical gangion the signal goes
Through the long ciliary nerves to the iris dilator
During sleep the pupil
Constricts
Stages of anesthesiaStage 1Stage 2Stage 3Stage 4
Excitatory phase – pupil dilationLight anesthesia – pupil dilationDeep anesthesia – pupil constrictionNear death – pupil dilation
Corneal pain causes the pupil to
Constrict – oculopupillary/trigeminal reflex
Prolonged pain causes activation of the
Sympathetic nervous system – pupil dilation
Systemic pain causes the pupil to
Dilate
Number of lashes on upper lid
100-150
Number of lashes on lower lid
50-80
The tarsal plates are made of
Fibrous and elastic tissue – NO cartilage
Meibomian glands are located in the
Tarsal plates
Blood supply to the eyelids Facial system Orbital system
External carotid A > facial A > angular A External carotid A > internal maxillary A > intraorbital ASuperficial temporal AInternal carotid A > ophthalmic A > dorsal nasal A, supratrochlear A, supraorbital A, lacrimal A
Venous drainage of the eyelids Facial system Orbital systems
Angular V > anterior facial V > external jugular V Superior temporal V > retiromandibular vein > external jugular VInfraorbital V > pterygoid venous plexus >internal maxiallary V >external jugularSupraorbital V, Supratrichlear V > superior ophthalmic V > cavernous sinus > internal jugular VLacrimal V > Inferior ophthalmic V > cavernous sinus > internal jugular VAnterior facial V
Lymphatic drainage of the eyelids and conjunctiva Medial portion of eyeLateral portion of eye
Submaxillary or submandibular nodes Preauricular or parotid nodes
Ophthalmic division of CN V receives sensory info from
Upper eye lid
Maxillary division of CN V receives sensory info from
Lower eye lid
Accessory lacrimal glands of Kraus and Wolfring are
Located in the conjunctiva – secrete serous/ aqueous fluid
Blood supply to the conjunctiva is through the
Peripheral arteriole arcades, marginal arteriole arcades and the anterior ciliary artery
Venous drainage of the conjunctiva is through the
Superior and inferior palpebral plexus
Sensory innervation to the conjunctiva is by the
Supratrochlear and Infratrochlear branches of CN V
Corneal diameter
Anterior. 11.7mm (horizontal) 10.6mm (vertical) Posterior 11.7mm circular
Corneal radius of curvature
Anterior 7.8mm, Posterior 6.5mm
Corneal thickness
Central 0.52mm, peripheral 0.67mm
5 layers of the cornea Epithelium Bowman’s layer Corneal stroma Descemet’s membrane Endothelium
Central 5mm has the greatest nerve density Cornea is 72-82% water50um (10% of corneal thickness) – continuous with conjSurface cells with microvilli – Wing cells –polygonal cellsBasal cells – germinal layer – regenerates epithelium Basal lamina – between basal cells an Bowman’s – regeneratesCellular fibrous tissue, made of MPS and GAG –not a true membrane – indistinguishable from stroma – CANNOT regenerate –90% corneal thickness (470um)Lamellae (200-250 – each 2um thick) – half life of each lamella is 100 days – lamellae are held in place by MPS and glycoproteins (ground substanceCells 2-5% stromal volume – fibroblasts synthesize collagen and MPS and bind lamellae in their ordered position – Schwann cells make up nerve sheaths – lymphocytes and macrophages aka posterior limiting membrane – true basement membrane for endothelium – ends at Schwalbe’s line – cen regenerate – sharp differentiation from stroma – made of collagen, MPS and GAGs – thickens with age – not innervatedsingle layer of hexagonal cells – synthesizes Descemet’s membrane – microvilli protrude into anterior chamber – very metabolically active – not innervated – regeneration limited
Hassal Henle warts are
Localized thickening in the peripheral cornea – seen as dark spots of holes in the endothelium
Radius of curvature of the sclera is
11mm
The sclera is thinnest
Posterior to the insertion of the recti muscles (0.3mm)
The sclera is thickest near the
Optic nerve (1.0mm)
Sclera contains
65% water
Tenon’s capsule is between the
Conjunctival stroma and underlying episcleral tissue
Episcleral space is the potential space between
Tenon’s capsule and the episclera
Suprachoroidal space is between the
Sclera and choroid and is where the long and short posterior ciliary nerves travel
Three layers of the sclera EpiscleraScleral stromaLamina fusca
Dense, vascular connective tissue Bundles of collagen and fibroblasts and ground substanceIncreased pigment
Volume of the anterior chamber
0.25ml
Anterior chamber depth
Women 3.41- 3.65mm – men 3.61-3.70mm
The internal scleral sulcus is mostly occupied by
Trabecular meshwork
The Apex of trabecular meshwork is located near
Schwalbe’s line (end of Descemet’s) – 3-5 layers thick
The Base of trabecular meshwork is formed by the
Scleral spur and the ciliary body – 15-20 layers thick
3 sections of trabecular meshwork Corneoscleral meshwork Uveal meshwork Pectinate fibers
Flat fenestrated sheets of tissue – filtering holes called intratrabecular spaces – larger holes are called “spaces of Fontana”, decrease in size toward Schlemm’s canal Most internal component – most anterior extension of the uvea – aka uveal “chords” – Aka iris processes – extend from iris root to the uveal meshwork – bridge the ACA – about 100 present per eye
Schlemm’s canal is a
Circular venous channel – lies on the outer portion of the internal scleral sulcus
Internal collecting channels of Schlemm’s canal are
Internal collector channels of Sondermann
Aqueous flow…
Trabecular meshwork (diffusion) > Schlemm’s canal (active transport) > deep scleral plexus > intrascleral venous plexus > aqueous veins of Asher > episcleral veins > anterior ciliary veins
The inner wall of Schlemm’s canal is called the
Justacanalicular tissue – lined with endothelium
The iris is thickest at the
Collarette (0.6mm) site of minor arteriole circle of the iris
Diameter of the iris =
12mm
Circumference of the iris =
37.5mm
The only pigment found in the iris is
Melanin
Blood supply to the iris Major arterial circle Minor arterial circle
In the ciliary body along iris border – anastomoses between Anterior ciliary and Long Posterior ciliary arteries Located at the level of the collarette – formed by radial branches from the major circle
Microscopic anatomy of the iris Anterior border layer Stroma Sphincter muscleAnterior epithelium Dilator musclePosterior pigment epithelium
Condensation of stromal tissue – fibroblasts and melanocytes – few collagen fibers Loose collagenm ground substance, elastin – continuous with CB stroma – melanocytes, lymphocytes, fibroblasts, mast cells – Clump cells (pigmented macrophages in papillary region)In pupillary portion of the stromaContinuous with the external pigment epithelium of the CB – contains myoepithelial cells – muscular processes make up the dilator muscle Developed from and an integral part of the anterior epithelium Single row, heavily pigmented columnar epithelial cells – basal surface contacts aqueous humor of post chember
Posterior chamber volume =
0.06ml (decreases with accommodation and dilation)
3 divisions of the posterior chamber Posterior chamber properZonular portion (Canal of Hanover)Retrozonular portion
Posterior to iris – anterior to lens zonules Space between zonule fibersPosterior to zonules – anterior to anterior hyloid of vitreous
The Pars plana (orbicularis ciliaris )portion of the CB
Runs from ora to ciliary processes -
The Pars plana produces
MPS for vitreous
The Pars plicata (corona ciliaris) produces
Aqueous humor
Layers of the CB include Unpigmented epithelium pigmented epitheliumstroma supraciliaris
Most internal layer – one cell thick – continuous anteriorly with the pigmented epithelium of iris and posteriorly with the nervous retina at ora Continuous anteriorly with unpigmented epithelium of iris and posteriorly with RPE at ora – thickens with ageInner connective tissue layer – loose tissue external to the basement membrane – collagen, blood vessels, nerves, fibroblasts and mast cells – contains ciliary muscle Most external layer – lies next to lamina fusca of sclera – fibroblasts and melanocytes
The ciliary stroma becomes choroids at the
Ora serrata
At ora the supraciliaris of the CB becomes the
Suprachoroid
At ora the external pigmented epithelium of CB
Becomes pigmented epithelium of the retina
The unpigmented epithelium of CB becomes
Nervous retina
Blood supply to the CB includes
2 long post ciliary As and 7 anterior ciliary As
3 portions of the ciliary muscle Longitudinal portion Radial portion Circular portion
(aka Brucke’s muscle, Meridional fibers) – origin at SS – insertion into choroid (epichoroidal muscle stars) – moves choroid anteriorly (oblique fibers) – origin SS – insertion at ciliary processes and Pars Plana – pulls pars plana anteriorly (aka Mueller’s muscle, Ciliary sphincter) – origin SS – insertion into anterior part of ciliary processes – constricts lens aperture
Zonules originate in the
Pars plana
The anterior Y suture is
Erect
The posterior Y suture is
Inverted
Y sutures are found in what area of the lens
Fetal nucleus
Lens epithelium is present at the
Equator and anteriorly under the capsule – NOT posteriorly
How many lens fibers are there in an adult lens?
2000
Large blood vessels in the stroma of the choroid are
Haller’s vessels
Small blood vessels in the stroma of the choroid are
Sattler’s vessels
Anterior ½ of choroid is supplied by
2 long posterior ciliary As to major arterial circle of the iris
Posterior ½ of choroid is supplied by
Many short posterior clilary As – form the circle of Zin-Haller
The choroid is mainly drained by the
4 vortex veins
Anterior ciliary veins drain the
Anterior ½ of the choroid via the limbal plexus
Pial veins drain the
Optic nerve meninges and part of the posterior choroid
Bruch’s membrane is the innermost layer of the choroid
Adjacent to the RPE
Layers of Bruch’s membrane Basement membrane of RPEInner collagenous zoneElastic layerOuter collagenous zoneBasement membrane of choriocapillaris
Actually a retinal layer (0.3um) No nerves no cells (1.5um)Backbone of Bruch’s membrane (0.8um)Fibroblasts, no nerves (0.7um)Outermost layer (0.14um)
The volume of the vitreous is
4ml
Vitreous attachments Vitreous basePeripapillary attachmentMacular attachmentHaloideocapsulary ligament
Firmest (2mm forward on CB and 4mm onto retina) Loosens with age4mm centered around fovea (Maxwell’s spot)Weigner’s or pectinate ligament – around post lens surface
The area of Martegiani is the area around the
ON where Cloquet’s canal flares out
Cloquet’s canal is a remnant of
Primary vitreous (hyaloid artery)
Layers of the retina RPE PhotoreceptorsExternal limiting membraneOuter nuclear layerOuter plexiform layer Inner nuclear layerInner plexiform layer Ganglion cell layerNerve fiber layerInternal limiting membrane
Uniform single layer of hexagonal shaped cells – more pigment in the macular region Thin, fenestrated layerCell bodies of rods and cones – nuclei and cytoplasmPhotoreceptor axons synapse with bipolar and horizontal cells – Muller cells fill in and have a nutritive functionCell bodies of horizontal, bipolar, Muller and amacrine cells Synapses between bipolar cells (1st order neuron) , amacrine cells and ganglion cells (2nd order neuron)Cell bodies of ganglion cellsAxons of ganglion cells Lines the vitreous face of the retina
In cases of retinal detachment the RPE…
Stays connected to Bruch’s membrane
The RPE provides photoreceptors with
Vitamin A, glucose and oxygen
Horizontal cells make connections between
Photoreceptors and other horizontal cells
Amacrine cells make connections between
Different ganglion cells
Photoreceptor layers receive blood from the
Choroid (outer nuclear and plexiform)
Inner retinal layers are supplied by the
Central retinal artery
Area centralis is located
4mm temporal and 0.08mm inferior to the optic disc
The perifovea is
1.5mm in width and 2.25mm from the fovea
The largest accumulation of nerve cells in the retina is
In the parafovea (2.1mm in width) around the fovea
The parafoveal layer has a thick
Outer plexiform layer (layer of Henle)
The fovea is
1.5mm in diameter – receptor layer has CONES ONLY
The foveola is
0.35mm across and contains only photoreceptors and glial cells
Ora serrata is located measures
8.5 mm from limbus…6mm from equator…25mm from ONH 2.1mm temporally…0.8mm nasally
The prelaminar portion of the optic nerve is protected by
Astrocytes that make up the intermediary tissue of Kuhnt, glial mantle of Fuchs or Graefe and the border tissue of Jacoby
The inner limiting membrane of Elschnig is where
The glial layer thickens over the ONH
The Meniscus of Kuhnt is where
Elschnig fills the optic cup
Nasal macular fibers cross at the
Center of the optic chiasm
The fist contact of the optic tract with the brain is the
Cerebral pedulcles
The optic tract divides sending the lateral part to the
LGN and the medial part to the superior colliculus and pretectum
Superior retina sends info to the
Medial part of the LGN
Interior retina sends info to the
Lateral part of the LGN
The cuneus (above calcarine fissure) maps the
Lower visual field (superior retina)
The lingual gyrus (below the calcarine fissure) maps
Superior visual field (inferior retina)
Layers 1,4,6 of the LGN are
Contralateral, nasal hemiretina, temporal crescent
Layer 2,3,5 of the LGN are
Ipsilateral, temporal hemiretina
Layer 4C alpha of the visual cortex has the
Ocular dominance columns
All ocular tissues develop from 3 embryological layers
Neural ectoderm, surface ectoderm and mesenchyme
Retinal layers derive from
Neural ectoderm
The optic cup is formed by the invagination of
Neural ectoderm
The innermost layer of the optic cup forms the
Inner and outer neuroblastic layers
The inner neuroblastic layer forms the
Ganglion cells, amacrine cells and Muller cells
Outer neuroblastic layer forms the
Bipolar cells, photoreceptors and horizontal cells
The outermost layer of the optic cup becomes the
RPE
The anterior part of the optic cup forms the
Epithelium of the ciliary body and posterior surface of iris
The inner (posterior) pigmented layer of the iris is
Continuous with the non pigmented layer of the CB epithelium
Outer lightly pigmented layer of iris is continuous with
The pigmented layer of the CB epithelium
The iris dilator and sphincter develop from the
Outer lightly pigmented layer of iris epithelium (neural ectoderm)
Surface ectoderm is induced to form the lens placode
By close association with the optic vesicle (neural ectoderm)
After the lens sack detaches the surface ectoderm
Continues on to form the eye lids
Surface ectoderm also forms the accessory glands of
Krause, Zeiss, Wolfring, Moll and meibomian glands
The lacrimal glands and drainage system also come
From the surface ectoderm
Anything that tears touch comes from the
Surface ectoderm
Mesenchyme originates from both
Neural crest and mesoderm
The hyaloid A and V are formed when
Mesenchyme enters through the embryonic/choroidal fissure
Corneal epithelium and primary stroma are formed by
Surface ectoderm
Corneal endothelium is formed by
The first wave of neural crest mesenchyme (7th wk)
The future corneal stroma is formed by the
Second wave of neural crest mesenchyme (8th wk)
Ciliary muscles are formed from
Mesenchyme
Vascular choroid and tough sclera are formed from
Mesenchyme
The EOMs are derived from
Mesenchyme
The bones of the orbit are formed from
Mesenchyme
Most bone sutures in the orbit close at
6-7 months
The sphenoid bond suture closes at the end of
The first year
SR, SO and levator develop from the
Superior mesoderm condensation
IR and IO develop from the
Inferior mesoderm condensation
MR and LR develop from
Both condensations
CN III, IV and VI evolve in the
Cranial portion of the neural tube (III 4th wk)(IV 7th wk)(all 8th wk)
The skin lids, glands and conjunctiva develop from
Surface ectoderm
The tarsal plate, orbicularis oculi, levator aponeurosis and smooth muscle of the eye lid are from
Mesoderm
Tearing begins
20-104 days after birth -
The lacrimal gland is fully developed at
3-4 years of age
The cornea will not develop is
The optic cup is missing
Corneal stroma, Descemet’s corneal endothelium and Bowman’s layer are derived from
Neural crest mesenchyme
Corneal nerves enter the tissue at
3 months – approach the epithelium by 5 months
Arborization of corneal nerves occurs in the stroma
Between the 6th and 9th months
Corneal diameter at birth =
10mm
Adult corneal diameter =
12mm
At birth the corneal curvature is
Flatter than the adults
The sclera develops from
Mesoderm
The lamina cribrosa forms at the
6th month
The third wave of neural crest mesenchyme forms
Iris stroma
The anterior chamber is present by the
5th month
Iris stroma is derived from
Neural crest mesenchyme during the 4th month
The pupil is fully formed by
8 months
If pupillary atrophy fails you see a
Persistent pupillary membrane
The ciliary muscle comes from
Mesoderm
The epithelial layers of the ciliary body come from
Neural ectoderm of the optic cup
The lens zonules develop from
Tertiary vitreous (neural ectoderm) (neuroepithelium of CB)
Primitive lens fibers are found at
The exact center of the lens throughout life
The embryonic nucleus is made up of
Primary lens fibers – optically clear central area (months 1-3)
The fetal nucleus is made of
Secondary fibers (3-8 mo fetal life)
Infantile nucleus is laid down beginning in the
Last weeks of fetal development and continuing to puberty
Adult nucleus is formed after
Puberty
The choriocapillaris is complete by the
6th week of development
The choriocapillaris is supplied by the
Short post ciliary As which branch off the long post ciliary As
Bruch’s membrane is composed of an
Inner ectodermal layer and an outer mesodermal layer
The primary vitreous contains the
Hyaloid artery
The secondary vitreous is
Avascular
The secondary vitreous is derived from
Neural ectoderm
Stages of retinal development Stage 1 Stage 2 Stage 3
Epithelial stage – retina develops from pseudostratified neuroepithelium Two zonesOuter primitive zone – inner and outer neuroblastic layersInner marginal zone – initially contains so nuclei – cells frominner neuroblastic layer migrate to itDifferentiation of the nervous elements – 1st ganglion cells then rod and cone photoreceptors
Muller cells extend from
The ELM to the ILM
Macular development is complete
3-4 months after birth
Retinal circulation during development involves Primitive dorsal ophthalmic A Ventral ophthalmic A
-branches from the internal carotid A -annular vessel at rim of optic cup-temporal long ciliary A – form the major arterial circle-anterior ciliary A -branches from the internal carotid A-anastomoses with dorsal ophthalmic A -develops into the nasal long ciliary A-degenerates
The hyaloid A is a branch of the
Primitive dorsal ophthalmic A
As the hyaloid system atrophies the
Central retinal A is formed – also the central retinal V
The optic nerve is surrounded by
All three layers of meninges of the brain
The macula gives rise to
1/3 of the optic nerve fibers (10% of retinal space)
The intermediary tissue of Kuhnt is composed of
Neuroglia
Perfusion pressure of retinal vessels =
MAP – IOP
Alpha 1 adrenergic receptors cause
Constriction of blood vessels
Beta 2 adrenergic receptors cause
Dilation of blood vessels
There is NO parasympathetic innervation to
Blood vessels
Forced closure of eye lids =
Orbital portion of the Orbicularis oculi (CN VII)
Spontaneous blinking and voluntary winking =
Palpebral portion of the orbicularis oculi
The menace reflex is a
Cortical reflex – afferent pathway is through the ON
Touch reflex involves…
CN V afferents and CN VII efferents
Glands of Krause are located in the
Conjunctival fornices
Glands of Wolfring are located along the
Tarsal plate
Dehydration of the cornea is mainly done by the
Endothelium
Partial pressure of oxygen – eyes open
155 mmHg
Partial pressure of oxygen – eyes closed
55 mmHg
The epithelium regenerates completely every
7 days
Hassel Henle bodies are
Localized thickenings of Descemet’s membrane (aging change)
Systemic acidosis with
Lower IOP
Index of refraction of aqueous
1.336
The energy needed by the lens epithelium comes from
Anaerobic glycolysis (used for active transport)
Soluble lens crystallines found in the cortex include
Beta cyrstalin 55% - alpha crystalin 15% - gamma crystalin 15%
Insoluble proteins of the lens nucleus include
Albuminoid
The lens has high amounts of
Glutathione
Retinal is an
Unsaturated aldehyde formed by oxidation of retinol (an alcohol)
In the dark the chromophore is in the
11-cis-retinal form
When a photon of light is absorbed the retinal
Undergoes cis/trans isomerization to become all-trans retinal
The all trans retinal dissociates from the
Opsin
Light blocks the entry of
Na into photoreceptor outer segment = hyperpolarization
The Neurotransmitter b/t photoreceptors and bipolar and amacrine cells is
Glutamate
Horizontal and amacrine cells directly modify the
Rate of electrical firing in bipolar cells
The major excitatory transmitter for horizontal cells is
Glutamate
In inhibitor of horizontal and amacrine cells is
GABA
The major excitatory transmitter for amacrine cells is
AcH
An inhibitor of amacrine cells is
Glycine
In the dark
Neurotransmitters are constantly released
In the light
The amount of NT released decreases
Horizontal cell receptor fields result in a
Larger, slower hyperpolarization that photoreceptors do
The amacrine cell gives a
Short, transient or phasic depolarization with a change in light level over a wide receptive field
The principle of univarience refers to the fact that
No matter how much above threshold the wavelength of light hits the photoreceptor…it will produce the same exact response
Blue cones have a peak density
1o from the fovea
Parvocellular cell layers of the LGN (3,4,5 and 6) relay
Ganglion cells to the visual cortex
Magnocellular cell layers of the LGN (1 and 2) relay
From the primary visual cortex to the secondary visual cortex and on to the MT and MST region
Contralateral (crossed) ganglion cell axons end up in
Layers 1,4,6 of the LGN
Ipsilateral (uncrossed) ganglion cell axons end up in
Layers 2,3,5 of the LGN
Simple cells of the LGN have
Elongated center surround receptors that respond to extended stimuli – stimulus must have the proper orientation
The response of Special simple cells depends on
The length of the stimulus
Complex cells require the correct
Orientation and size stimulus
As long as the orientation is correct, a stimulus
Anywhere in the receptive field of a complex cell will cause a response
The primary input to the cortex form the LGN goes to
Layer 4
Collaterals of both the magno and parvo cells terminate
In layer 6 of the cortex
Intralaminar cells terminate in
Layers 2 and 3
Spiny stellate can pyramidal cortex cells are
Excitatory
Smooth stellate cells are
Inhibitory
Pyramidal cells have
Long, large axons and spiny type processes
Stellate cells have
Short axons and either smooth or spiny processes
Ocular dominance is the
Classification of the binocularity of a particular cell
Group 1 cells
Stimulated only by contralateral eye
Group 2 and 3 cells
Codominant – more by contralateral eye
Group 4 cells
Equal binocular response
Group 5 and 6 cells
Codominance – more by ipsilateral eye
Group 7 cells
Only to ipsilateral eye
Chromophore of rods and cones
11-cis-retinal (light catching molecule)
Light causes the 11-cis-retinal to changes to
All-trans-retinal through photoisomerization
The all trans form dissociates from the
Opsin and is released into the cytosol
The all-trans-retinal is converted back to 11-cis-retinal
By retinal isomerases in the cytosol
The all-trans-retinal activates the
G protein, transducin which activates a G protein cascade
The G protein cascade results in a
Decrease in cGMP concentration in the cytosol
cGMP is then released from its binding site on
Sodium channels – causes Na+ channels to close
The closing of the Na+ channels causes a
Hyperpolarization of the membrane
Hyperpolarization leads to the
Transmission of the nerve pulse
In the dark the outer segment of the photoreceptor is
Highly permeable to Na+