Ocular Anatomy (Done) Flashcards
What is Telecanthus?
An abnormally increased distance between the medial canthi of the eyelids
What makes the skin layer of the eyelid unique?
It is the thinnest in the body and contains NO FAT!
Which eyelid layer is located between the outer skin layer and the orbicularis layer?
Subcutaneous areolar layer
What happens if the orbicularis oculi is paralzyed?
ECTROPION will occur
What is the purpose of the orbital portion of the orbicularis?
used for forceful eyelid closure
What is the purpose of the palpebral portion of the orbicularis?
Spontaneous and reflex blinking
What are the 2 specialized areas found in the palpebral portion of the orbicularis?
- Muscle of Riolan (pars ciliaris)
2. Muscle of Horner (pars lacrimalis)
What is the function of the muscle of Riolan?
- Keeps lid margin tightly attached to the globe during eye movements
What is the gray line?
a groove located in between the eyelash insertions and the meibomian glands
What is the function of the muscle of Horner?
consists of fibers that encircle the canaliculi and help drain tears into the lacrimal sac
Which layer lies in between the orbital septum and the orbicularis?
Submuscular areolar layer
Which structures are located in the submuscular areolar layer?
Levator aponeurosis and the palpebral portion of the lacrimal gland, as well as the peripheral and marginal arcades
What are the functions of the orbital septum?
- prevents fat from falling onto the eyelids
2. keeps infections in the anterior portion of the eyelid
The superior orbital septum serves as the insertion site for the ____________.
Levator aponeurosis
Does the orbital septum protect the lacrimal sac from infection?
NO!
Where does the levator originate from? What is the function of the levator muscle?
lesser wing of the sphenoid at the orbital apex; it is the main lid retractor (15 mm)
What is Whitnal’s ligament?
serves as a fulcrum and changes the course of the muscle from anterior-posterior to superior-inferior»this is located on the zygomatic bone
How is the superior palpebral furrow formed?
By the insertion of the levator aponeurosis into the upper eyelid
How is the inferior palpebral furrow formed?
formed by indirect attachment of the inferior rectus muscle into the skin of the lower eyelid.
What is the purpose of Muscle of Muller?
Sympathetic innervation»minor retractor providing 1-3 mm eyelid lift
Which muscle provides minor lower lid retraction?
Inferior tarsal muscle»also innervated by sympathetic system
A person w/ CN III palsy is being affected by parasympathetic or sympathetic system?
Parasympathetic»lack of innervation to the levator muscle
Where are meibomian glands located in relation to the eyelash follicles?
Located BEHIND the eyelash follicles within the tarsal plate
Where are goblet cells predominantly found?
Inferonasal fornix»also bulbar conjunctiva sometimes (more temporally)
What are the 2 layers of the palpebral conjunctiva?
Epithelial layer and the Stroma
The stromal conjunctival layer is broken down into
- Superficial lymphoid layer
2. Deep fibrous layer
What is found in the superficial lymphoid layer? (there are many)
IgA, eosinophils, macrophages, PMN’s, mast cells
What is found in the deep fibrous layer of the conjunctiva?
Accessory lacrimal glands, nerves, and blood vessels of the eye
What is the purpose of Zeis glands?
helps prevent the eyelashes from becoming brittle»usually 2 per eye
Which type of glands are Moll?
Modified apocrine glands»they empty their contents onto Zeiss glands and eyelash follicles
What type of glands (or gland secretion) are Krause? Where they located?
Merocrine secretion located in the FORNICES of the conjunctiva
Where are glands of Wolfring located?
Tarsel conjunctiva»larger and less numerous than glands of Krause
What happens during holocrine secretion?
whole cell is shed into the lumen (remember, meibomian glands and zeis are examples)
What happens during apocrine secretion?
portion of the plasma membrane buds off the cell and enters the lumen for secretion
What happens during merocrine secretion?
cells secrete their substances by exocytosis, thereby remaining intact after secretion
Where do the lateral lymphatics drain?
Pre-auricular lymph nodes (parotid)
Where do the medial lymphatics drain?
Submandibular nodes
Which branch of the facial nerve innervates the orbicularis oculi?
Zygomatic branch of CN VII
What is the function of the Corrugator muscles?
Medial depressor of the eyebrow»fibers run OBLIQUELY and pull eyebrow down and inward for a look of sorrow
»produces vertical wrinkles on the forehead
What is the function fo the Procerus?
Pulls the skin between the eyebrows downward for an appearance of menace or aggression
What is the primary lateral depressor of the eyebrow?
Orbicularis Oculi
What type of gland secretion is the lacrimal gland?
Tubuloacinar exocrine gland secretion that releases its products via MEROCRINE secretion
Lacrimal gland is separated into palpebral and orbital portions by what..?
By the tendon of the superior levator palpebrae muscle
The lacrimal gland receives innervation from which nerve?
Lacrimal nerve of the pterygopalatine ganglion of CN VII
What structure is responsible for keeping the punta open?
Lacrimal papilla
What is the purpose of the canaliculi and which type of cells are found in it?
stratified and pseudostratified epithelium cells»canaliculi connects each puncta to the lacrimal sac
Which muscle surrounds the canaliculi?
Muscle of Horner (part of orbicularis oculi)
During eyelid closure, what function does the muscle of Horner play in the drainage system?
Muscle of horner contracts the canaliculi to assist in tear drainage
Where does the lacrimal sac lie and which cells make the lacrimal sac?
Lies within a fossa in medial orbital wall formed by post. lacrimal crest of the lacrimal bone
»superficial columnar and deep basal layers w/ microvilli and goblet cells
The orbital septum is located _______ to the lacrimal sac, making it more susceptible to infection.
POSTERIOR
The nasolacrimal duct lies adjacent to the ___________.
Maxillary sinus
Where does the superior oblique originate from?
Lesser wing of the sphenoid bone and the CTR.»it travels anteriorly before looping through the trochlea to insert on the superior lateral globe behind the equator
The IR sheath combines with the IO sheath to form the ______________.
Suspensory ligament of Lockwood.
The trochlea is considered the physiologic origin of the ______ because it changes its direction of action.
Superior oblique
All EOM’s pierce____________, which sends a “sleeve” of connective tissue with the tendons prior to merging with sclera
Tenon’s capsule
Superior oblique is responsible for pure depression when the eye is aDducted ___ degrees towards the midline.
51 degrees
Inferior oblique is responsible for pure elevation when the eye is aDducted ___ degrees towards the midline.
55 degrees
Superior rectus is responsible for pure elevation when the eye is aBducted ___ degrees away from the midline.
23 degrees
Inferior rectus is responsible for pure depression when the eye is aBducted ___ degrees away from the midline.
23 degrees
The EOM’s are predominantly supplied by which artery? and which 2 branches within that artery?
Ophthalmic artery
- Superior lateral branch (SR, LR, SO)
- Inferior medial branch (MR, IR, IO)
What is the orbital fascia?
composed of connective tissue that covers the bones of the orbit»provides support to blood vessels within the orbit and serves as attachment site for muscles, tendons, and ligaments
Where does the optic chiasm lie in relation to the pituitary gland?
It lies ABOVE the pituitary gland»damaged to NASAL fibers causes bi-temporal hemianopsia
The optic canal in each eye is located just lateral to the center of the ________.
Sphenoid body
The optic canal is located within the ___________.
Lesser wing of the sphenoid
In which bone of the orbit is the foramen rotundum, ovale, and spinosum located?
Greater wing of the sphenoid
Lesser wing projects anteriorly to connect with the ___________ to form the roof of the orbit.
Frontal bone
Is the cavernous sinus behind or in front of the SOF?
CS lies posterior to the SOF
Which nerves pass through the SOF and the CTR?
Think “NOA”»nasociliary nerve, oculomotor nerve, and abducens nerve, also sympathetic root of the ciliary ganglion
Which nerves pass through the SOF and ABOVE the CTR?
superior ophthalmic vein, frontal nerve, lacrimal nerve, and trochlear nerve
Which bones comprise the roof of the orbit?
Lesser wing and frontal bone
Which bones comprise the floor of the orbit?
Maxillary, palatine, and zygomatic
Which bones comprise the medial wall of the orbit?
Maxillary, ethmoid, lacrimal, and body of sphenoid»thinnest and smallest wall of orbit
Which bones comprise the lateral wall of the orbit?
Greater wing and zygomatic bone
What are the 3 main important branches of the external carotid artery?
- Facial artery
- Maxillary artery
- Superficial temporal artery
Which artery is the terminal branch of the facial artery? and what structure does it supply?
Angular artery»which communicates with the dorsal nasal artery to supply medial canthus
What does the infraorbital branch of the maxillary artery supply?
it supplies the IR and IO as well as the lower eye lid and the lacrimal sac before joining the angular and dorsal nasal artery
What will happen if the SPCA’s are damaged?
this will lead to suffocation and irreversible damage of the optic nerve head»_space;AAION happens
Which artery is the first branch of the ICA?
Ophthalmic artery
What are the 7 branches of the ophthalmic artery? What are the 2 terminal branches?
CRA, lacrimal, muscular, SPCA’s, LPCA’s, supraorbital, ethmoid
»Terminal branches= supratrochlear & dorsal nasal artery
What does the lacrimal artery supply?
lateral rectus and lacrimal gland
the lateral palpebral arteries anastomose with the medial palpebral arteries to form the ___________ of the eyelids
palpebral arcades of the eyelids
What does the Muscular artery supply?
Superior lateral muscular artery supplies LR, SR, SO, and levator
Inferior medial muscular artery supplies the MR, IR, and IO.
What does the SPCA’s supply?
Supplies the superficial optic nerve head, as well as the posterior choroid, including the macula
What is the Circle of Zinn?
the SPCA’s branching within the choroidal stroma to form this arterial network
What do the LCPA’s supply?
Anterior choroid before travelling to ciliary body to join with ACA’s to form Major arterial circle of the Iris
Which structures are supplied by the Supraorbital artery?
SR, SO, levator muscle, superficial scalp and forehead.
What does the Ethmoid artery supply?
Branches supply the sphenoid, frontal, and ethmoid sinuses.
What does the Supratrochlear artery supply?
Skin of the forehead and scalp, as well as the muscles of the forehead
What does the Dorsal nasal artery supply?
Lacrimal sac»it then travels along side of nose to join angular artery
After draining the inner 6 layers of the retina, where does the Central Retinal Vein drain through?
Exits optic nerve and enters Cavernous sinus, either directly or after joining the Superior ophthalmic vein
What is the major threat to vision in patients with a CRVO?
Neovascular glaucoma (90 day glaucoma)
Which parts of the eye are drained by the Anterior ciliary arteries?
Iris, ciliary body, conjunctiva, and Schlemm’s canal
Where do the Anterior ciliary arteries drain into?
Into the Superior and Inferior ophthalmic veins
What do Vortex veins drain? Where do they drain into?
They drain blood from the choroid. Vortex veins drain into the Superior and Inferior ophthalmic veins
What is the largest vein in the orbit?
Superior ophthalmic vein
Into which structure does the SOV drain?
Drains into the cavernous sinus (first passes through the superior orbital fissure)
The Inferior Ophthalmic vein drains via 2 branches. Into which structures do these branches drain, respectively?
- Inferior branch exits orbit through IOF and drains into the Pterygoid plexus to communicate w/ facial veins.
- Superior branch exits orbit through SOF and into the Cavernous sinus
The supraorbital vein joins the ________ vein near the medial angle of the orbit to form the ________ vein.
Joins the frontal vein to form the Angular vein
The Angular vein eventually becomes the ___________ vein at the lower margin of the orbit.
It becomes the Anterior facial vein
The common Facial vein drains into the ____________ vein.
Internal jugular vein
The Anterior facial vein receives blood from where?
Receives blood from the pterygoid plexus, as well as superior and inferior palpebral veins.
The pterygoid venous plexus communicates with _____________ vein and __________ via orbital veins and emissary veings of the cranium.
Anterior facial vein and Cavernous sinus
The Posterior Facial Vein is formed by the union of the __________ vein and the ________ vein within the parotid gland.
Superficial temporal vein and the maxillary vein
The anterior branch of the Posterior Facial Vein unites with the anterior facial vein to form the _________ vein, which drains into the ____________ vein.
Common facial vein, which drains into the internal jugular vein.
The posterior branch of the Posterior Facial Vein joins with the __________ vein to form the _______________vein.
Posterior auricular vein, which forms the External jugular vein
What is the purpose of dural sinuses?
Venous channels located in the dura mater of the brain that are responsible for draining blood from the head back to the heart.
The External jugular vein is formed by the union of the _________ vein and the _________ vein and drains blood from the superficial face.
Retromandibular vein and the Posterior auricular vein.
The sphenoid sinus is _______ and the optic chiasm is ________ to the cavernous sinus.
Inferior and Superior
Cavernous sinus receives blood from which veins?
Superior and ophthalmic veins as well as superficial middle cerebral vein and inferior cerebral veins.
Where does the cavernous sinus drain?
Drains into the superior and inferior petrosal sinuses, ultimately draining into the Internal jugular vein to carry blood to the heart!
What is the “Triangle of Death”?
area of the face where infections in this area can gain access to the brain through the cavernous sinus because of venous communication between the facial vein and the ophthalmic veins.
Which nerves/arteries/fibers are found in the cavernous sinus?
CN III, IV, V1, V2, and VI, ICA, preganglionic parasympathetic fibers and preganglionic parasympathetic fibers that travel with CN III.
»Remember, ICA aneurysm will likely cause CN VI palsy due to close association.
What are the signs and symptoms of Tolosa-Hunt Syndrome? Which CN’s are affected?
inflammation of the SOF and/or cavernous sinus affecting CN 3-6, results in painful external ophthalmoplegia and diplopia
What is the meeting place for the superior sagittal, straight, occipital, and transverse sinuses and is located on the occipital protuberance?
The Confluence of the Sinuses
The Sigmoid sinus receives the inferior petrosal sinus, which exits the skull eventually becoming the ____________ vein.
Internal jugular vein.
Where does the Inferior Petrosal sinus drain?
Into the internal jugular vein.
Where is the Superior Sagittal sinus located? and where does it drain into?
Within the superior falx cerebri and it drains into the Right transverse sinus.
Inferior Sagittal sinus travels posteriorly to join the great cerebral vein to form the _________ sinus.
Straight sinus.
Into which sinus does the Straight sinus drain into?
Left Transverse sinus.
Which sinus does the Occipital sinus eventually drain into?
Left transverse sinus.
Transverse sinus eventually travels inferiorly to form the ___________ sinuses.
Sigmoid Sinus (which eventually becomes the Internal jugular vein.
The tear/cornea interface contributes __D and the cornea/aqueous humor interface contributes __D to the total refractive power of the cornea
5 D and -6 D
The corneal epithelium consists of what type of cells?
Stratified squamous non-keratinized epithelium (contains 5-6 layers in total)
What are the different layers of the corneal epithelium? and what are the charateristics of them?
- Surface layer»2 layers of non-keratinized squamous cells»secrete glycocalyx and contains microvilli to increase surface area for tear film stability
- Wing cell layer»2-3 cell layers joined by desmosomes
- Basal layer»only mitotic layer–composed of 1 layer of columnar cells
»Basal layer secretes its own basement membrane (hemidesmosomes)»also from the BM to corneal stroma
Bowman’s layer is composed of what type of collagen?
Type 1
Name as many corneal conditions related to Bowman’s layer….
Band keratopathy, Pterygia, Crocodile shagreen, Reis-Buckler dystrophy, Keratoconus, and Refractive surgery
Which type of collagen is found in the corneal stroma?
Type 1
What is found in the corneal stroma?
Keratocytes, collagen fibrils, ground substance (which contains GAG’s)–KERATIN SULFATE!
What produces collagen fibrils and extracellular matrix?
KERATOCYTES
Which type of collagen is found in Descemet’s membrane?
Type IV»descemets membrane is the BM produced by the corneal endothelium
What are 3 corneal conditions that affect Descemet’s membrane?
Hydrops, Haab’s striae, and Hassall-Henle bodies
What type of cells compose the corneal endothelium?
Single layer of squamous cells ~ 5 um thick
Which type of junctions are found in the corneal endothelium?
Maculae occludens»weak barriers that allow AA’s, glucose and nutrients from the aq. humor to enter into the cornea
When do corneal nerves lose their myelin sheath?
After travelling 2-4mm in mid stroma and before they penetrate Bowman’s layer
What are the 2 layers that make up the conjunctiva?
- Stratified non-keratinized epithelial layer»composed of cuboidal /columnar cells in the palpebral conjunctiva that become squamous cells in the bulbar conj
- Submucosa: loose CT layer that is separated into 2 layers
What are the 2 layers of the conjunctival submucosa?
- Outer lymphoid layer
2. Deep fibrous layer
What is found in the Outer lymphoid layer of the conjunctival submucosa?
IgA, macrophages, mast cells, lymphocytes, PMN leukocytes, eosinophils, and Langerhans cells
What is found in the Deep fibrous layer of the conjunctival submucosa?
collagen, fibroblasts, blood vessels, lymphatic vessels, nerves, and accessory lacrimal glands.
Which type of cells make up the Marginal conjunctiva?
Stratified columnar epithelial cells
Which type of cells make up the Tarsal conjunctiva?
Stratified columnar epithelial cells
Which cells make up the Bulbar conjunctiva?
Stratified squamous cells
What are some histological and anatomical changes that occur at the limbus?
- limbal epithelium is 10 cell layers compared to 5 layers of the corneal epithelium
- Bowman’s & Descemet’s ends at limbus
- Conj. stroma, episclera, and Tenon’s capsule begin at the limbus
What are Palisades of Vogt?
spoke-like projections of limbal conjunctiva that extend 4mm from the edge of the cornea.
What cells and part of the conjunctiva make up the Plica Semilunaris?
Stratified squamous bulbar conjunctiva that folds at the medial canthus, providing slack in the conj during lateral eye movements.
What is the Caruncle?
Hybrid of conjunctiva and skin that contains sebaceous glands, sweat glands, and goblet cells and is located on the medial side of the plica semilunaris
Which blood vessels supply the Palpebral conjunctiva?
Marginal and Peripheral palpebral arcades.
Which blood vessels supply the Posterior bulbar conjunctiva?
Peripheral palpebral arcades.
Which blood vessels supply the Anterior bulbar conjunctiva?
Anterior ciliary arteries
Palpebral and bulbar conjunctiva are drained by the _____________ veins.
Anterior ciliary veins.
What innervates the Bulbar conjunctiva?
LPCN’s»superior palp. conj. innervated by frontal and lacrimal nerves, inferior palp. conj innervated by lacrimal nerve and infraorbital nerve
The lens is aspherical, becoming __________ towards the periphery.
FLATTER
Is the anterior or posterior curvature of the lens steeper?
Posterior (5-8 mm) vs. Anterior (8-14 mm)
What 2 characteristics of the lens helps to reduce spherical aberration?
- Peripheral flattening
2. Gradient index of refraction
What is the lens capsule secreted by?
Anterior lens epithelium
Which type of collagen makes up the lens capsule?
Type IV»it is thinnest at posterior pole and thickest at anterior pole
Where do the lens zonules attach?
Extend from the NPCE and insert into the Anterior lens capsule
Which type of cells make up the lens epithelium?
A single layer of cuboidal epithelial cells
How are lens epithelial cells joined?
By Maculae occludens and gap junctions»Remember, there is NO POSTERIOR LENS EPITHELIUM as it was used to form the primary lens fibers during embryological development
Which region of the lens contains mitotic epithelial cells that become secondary lens fibers?
The pre-equatorial region (aka germinal zone)
What is the lens cortex made of?
65-70% water, 30-35% protein
What is the purpose of alpha crystallins?
Act as molecular chaperones by helping beta and gamma crystallins recover from injuries, thus preventing degradation of lens fibers and loss of lens transparency.
What is the index of refraction of the vitreous and aqueous humor?
1.336
Where is the index of refraction higher in the lens?
The nucleus compared to the anterior lens where it is 1.38
Which eye structure produces lens zonules?
Basement membrane of the NPCE in the pars plana and pars plicata
Where do primary lens zonules attach?
Attach directly to the lens capsule in the pre- and post-equatorial regions of the lens.
What do the secondary lens zonules do?
They connect primary lens zonules to one another or to the non-pigmented ciliary epithelium of the pars plana.
What is the mean radius of curvature of the sclera?
11.5 mm
Where is the sclera thickest and how thick?
At the posterior pole 1.0 mm
Where is the sclera thinnest and how thin?
Under the recti tendon insertions 0.30 mm
What minimally innervates the sclera?
LPCNs and SPCNs
In which layer of the sclera are the anterior ciliary arteries found (capillary network)?
Episclera»characteristic ciliary flush (i.e. circumlimbal injection)
The sclera proper is thick, dense, avascular CT that is continuous with the _________________.
Corneal stroma
Where is the Lamina Fusca located in relation to the sclera?
The innermost layer of the sclera ADJACENT to the choroid
Episclera, lamina fusca, conjunctival epithelium, Tenon’s capsule, Sclera proper, and conjunctival stroma»Place these in order from most ANTERIOR to POSTERIOR.
Conjunctival epi, conj. stroma, Tenon’s, episclera, sclera proper, and lamina fusca
Which arteries/veins are found in the Anterior Emissaria of the sclera?
Anterior ciliary arteries, episcleral arteries, aqueous veins of Acher (drain aq. humor from Schlemm’s canal), and LPCN’s
What is the approximate diameter of the anterior chamber angle?
11-12 mm, with a 3.6 mm depth.
The scleral spur is the origin site for the ___________________.
Longitudinal ciliary muscle fibers
Which layers of the TM contribute to the Uveoscleral meshwork?
The innermost 1-5 layers of the TM that are adjacent to the anterior chamber and inward to the scleral spur.
What is the flow of aqueous through the uveoscleral pathway?
- Between ciliary muscle fiber bundles 2. suprachoroidal space 3. sclera OR drains through the 1. anterior ciliary veins 2. vortex veins
How do Prostaglandins change the uveoscleral pathway?
They decrease resistance by RELAXING the ciliary muscle and causing changes within the ECM, resulting in an increase in uveoscleral outflow.
Which layers of the TM compose the Corneoscleral meshwork?
The outer 8-15 layers of the TM that are located closer to Schlemm’s canal and extend between the scleral spur and the cornea.
What is the Juxtacanalicular tissue (JXT)?
it is the outermost portion of the TM and separates the inner wall of Schlemm’s canal from the TM
Which part of the TM contains the most resistance to aqueous outflow?
Juxtacanalicular tissue
Which outflow mechanism is pressure independent?
Unveoscleral pathway
What does it mean when the corneoscleral pathway is Pressure Dependent?
The IOP must be greater than the episcleral venous pressure in order for aq. humor to flow into Schlemm’s canal
Aq. humor can drain out of Schlemm’s canal through 2 major routes:??
- Short efferents»deep scleral venous plexus»intrascleral venous plexus»episcleral venous plexus
- External collector channels (Aq. veins of Ascher)»episcleral venous plexous
What is the path of drainage beginning from the Episcleral venous plexus and ending in the right atrium of the heart?
Episcleral venous plexus»sup/inf ophthalmic veins»cavernous sinus»sup/inf petrosal sinus»internal jugular vein»brachiocephalic vein»superior vena cava»right atrium of the heart
The inner border of Schlemm’s canal is located against the _________ and ________.
Scleral spur and TM
What are Schwalbe’s contraction furrows?
The iris at the pupillary margin that represents variations in the thickness of the Posterior pigmented iris epithelium
Where is the iris thickest? where is it thinnest?
Collarette region and Iris root
What was the attachment site for fetal pupillary membrane during embryonic development?
Collarettes
What do the iris collarettes divide the iris into?
Divides it into pupillary and ciliary zones
What is Aniridia?
Bilateral condition characterized by complete or partial absence of the iris.»highly associated with glaucoma (75%) due to angle closure from PAS»pts. can also have microcornea, lens subluxation, and optic nerve hypoplasia
What are the 4 layers of the Iris?
- Anterior border layer
- Iris stroma
- Anterior epithelium
- Posterior Pigmented iris epithelium
What role does the anterior border layer play?
Provides definitive color to the iris»Iris color is determined by the AMOUNT OF MELANIN within the melanocytes, NOT the number of melanocytes
The only condition characterized by a lack of pigment within the iris epithelial layers is ____________________.
Oculocutaneous Albinism
What is the purpose of iris crypts?
Collagenous columns located in the anterior border layer that serve as passageways for aq. humor to enter the iris stroma
What are possible causes for Heterochromia?
Congenital, topical prostaglandins, chronic inflammation
List as many things you can that are found in the Iris Stroma?
LPCNs, SPCNs, Major arterial circle of the Iris, Minor arterial circle of the iris, radial veins and the Sphincter muscle
What makes up the Minor arterial circle of the Iris?
Found in the Iris»formed by anastomoses of the radial arteries that branch from the Major ACI
Anterior iris epithelium becomes the ___________________ of the ciliary body.
PIGMENTED epithelium
Posterior iris epithelium becomes the ___________________ of the ciliary body.
NON-PIGMENTED epithelium
In which layer of the iris is the Dilator muscle found?
Anterior Epithelium
Why is Pigment dispersion syndrome associated with Glaucoma?
Released pigment from the iris epithelial layers may accumulate on the ant. capsule, iris surface, corneal endothelium, or TM and may results in glaucoma due to poor aqueous outflow
What are the 3 regions composing the posterior chamber?
- Posterior chamber proper
- Canal of Hannover (circumlental space)
- Canal of Petit (retrolental space)
The ciliary body is triangular in shape. The apex points towards posteriorly towards the ____________, while the base located anteriorly points at what 3 structures?
Ora Serrata
Scleral spur, iris root, and anterior chamber
What are Valleys of Kuhnt?
Heavily pigmented areas located between the ciliary processes.
How many ciliary processes does the pars Plicata contain?
70-80 ciliary processes that extend into the posteriro chamber
What is the flow of aq. humor beginning at the Pars plicata?
Pars plicata»posterior chamber»pupil»anterior chamber»trabecular meshwork
What are Dentate processes?
Extensions of the peripheral retina onto the ciliary body
What are Oral bays?
Posterior extensions of the pars plana that lie between the dentate processes.
Lens zonules produced by the pars plana extend first to the ____________________ before inserting into the lens ca
Valley of Kuhnt
What is the outermost layer of the ciliary body?
Supraciliaris»it is loosley attached to the underlying sclera
»blood vessels and nerves travel through it as well
The ciliary muscle is anchored anteriorly in the _________ and posteriorly in the ____________.
Scleral spur, Stroma of the choroid
What are the 3 types of fibers found in the ciliary muscle?
- Longitudinal
- Radial
- Muller’s annular muscle
In which layer is found the Major arterial circle of the iris?
Ciliary stroma
The ciliary stroma is highly ________ and contains the MACI.
Vascularized
Aqueous humor is produced from _________ that escapes the blood stream via fenestrated capillaries of the MACI.
PLASMA
Ciliary epithelium is composed of 2 layers joined apex to apex via ________________ to form part of the blood-aqueous barrier.
Zonula Occludens
Veins within the ciliary body eventually drain through the ________________.
Vortex veins
Choroid is thickest in the __________ and thinnest at the _____________.
posterior pole (0.2 mm) and ora serrata (0.1 mm). >>contains 2 central vascularized layers surrounded by 2 non-vascularized membranes (4 layers total)
what are the 4 layers of the choroid from most anterior to posterior?
Suprachoroid lamina (lamina fusca), Choroidal stroma, Choriocapillaris, and Bruch’s membrane
________________ are the most common primary intraocular tumors in adults.
Choroidal melanomas
In the choroidal stroma, the choroidal vessels are innervated by the __________ system, which causes vasoconstriction.
Sympathetic system
Choriocapillaris contains fenestrated capillaries that are most concentrated within which region of the retina?
MACULA
|»_space;choriocapilllaris contains few Pericytes that surround the capillary walls and provide local regulation of blood flow
What are the 5 layers of Bruch’s membrane from choroid to retina?
BM of choriocapillaris, outer collagenous layer, elastic layer, inner collagenous layer, and BM of RPE
What physiological effect do phospholipids have on Bruch’s membrane w/ age?
Phospholipids cause Bruch’s membrane to become Hydrophobic, thereby inhibiting water movement, and thereby transporting nutrients.
Between which layers are Drusen found?
Between inner collagenous zone and BM of RPE
In which conditions, can you find a CNVM?
CHBALA»choroidal rupture, histoplasmosis, angioid streaks, Leuker cracks,
What are the associated diseases with Angioid streaks? (Remember, PEPSI)
Pseudoxanthoma elasticum, Ehler Danlos syndrome, Paget’s disease, Sickle cell disease, and Idiopathic
Sympathetic fibers from superior cervical ganglion cause ___________ of the choroidal vessels.
VASOCONSTRICTION
CN VII Parasympathetic fibers from pterygopalatine ganglion cause ___________ of the choroidal vessels.
VASODILATION
What components make up the vitreous? Which type of collagen?
H2O within a matrix of hyaluronic acid and Type II collagen
What is the predominant cell type in the vitreous?
Hyalocytes, which are located exclusively in the vitreous cortex.
What is the role of Hyalocytes?
They are responsible for synthesizing HA and also may have phagocytic properties.
What is the purpose of Hyaluronic acid?
Is a GAG that helps to maintain spacing between collagen fibrils
Where are fibroblasts located in the vitreous and what is their role?
Predominantly located in the vitreous base and role is to synthesize collagen fibrils
What are the 5 major attachments of the vitreous to the retina from strongest to weakest?
Vitreous base, posterior lens, optic disc, macula, then retinal vessels
Which vitreous attachment is most likely to cause a retinal tear or break?
> > Tightest areas will most likely cause a retinal tear (aka vitreous base most likely to cause retinal tear)
After development, the hyaloid artery regresses to the optic disc where it becomes the ____________.
Central retinal artery
The posterior end of Cloquet’s canal near the optic disc is called the _______________.
Area of Martegiani
What is the function of RPE microvilli?
Phagocytize the PR outer segments
List as many functions of RPE that you can…
- Phagocytosis of PR discs
- Transport of metabolites, ions & water
- Vit. A storage and metabolism
- Part of blood-retinal barrier
- Absorbs light
- Produces VEGF and PEDF (counterbalances effects of VEGF)
What do the Inner segments of PR do?
They produce Photopigments!
What are the 3 parts of the Inner segment of a PR? and what purpose do each of them have?
- Myoid»contains ER & golgi for protein synthesis
- Ellipsoid»outer layer of inner segment that is packed with mitochondria
- Cilium»connects inner & outer segments
What is the Outer segment of a PR?
Contains the stacks of discs that contain photopigments produced by the Inner segments
»600-1000 discs for rods and 1000-1200 discs for cones
In rods or cones are found free-floating discs?
Rods= free-floating Cones= membrane bound
Rods terminate in _________, while cones terminate in _____________.
Spherules, Pedicles
Where is rhodopsin density greatest?
5mm (20 degrees) concentrically from the fovea
Cones have the same chromophore, but differ in their protein (opsin) component)…what is this chromophore?
11-cis-retinal
The fovea is __mm temporal and __ mm inferior to the center of the optic nerve
5 mm and 0.4 mm
What is found in the outer nuclear layer?
Cell bodies of rods and cones.
What is found in the outer synapse layer?
Synapses between rods and cones and the dendrites of bipolar and horizontal cells.
What are spherules and pedicles, respectively?
Spherules are the synaptic endings of rods (between rods and bipolar/horizontal cells)
Likewise, pedicles are the terminal endings for cones
Where are hard exudates located?
OPL
Retinoschisis describes a splitting of the ________ layer of the retina.
OPL.
what cells are found in the inner nuclear layer?
cells bodies of bipolar, horizontal, amacrine, muller cells, and interplexiform cells
Bipolar cells synapse with _______ in the OPL and with ganglion cells in the _______.
OPL and IPL
What is the most common cell found in the retina?
Muller cells»they stretch from ILM to ELM and give structural and nutritional support
What is found in the inner plexiform layer of the retina?
Synapses between bipolar and ganglion cells
_____________ modify the synapse between bipolar and ganglion cells.
Amacrine cells
_________________ cells are responsible for resolving fine detail because they carry informaiton from a single cone photoreceptor within the fovea
Midget ganglion cells
Where is the NFL thickest at the optic nerve?
Superior and inferior margins.
The NFL is NOT present in ____________ part of the retina.
Fovea»it begins in the parafoveal region.
Papillomacular bundle consists of NFL fibers that extend from macula on the ________ margin of the optic disc.
Temporal
CWS, splinter hemorrhages, and flame hemorrhages all occur in what layer of the retina?
Nerve fiber layer
In which retinal layer are dot or blot hemorrhages located?
Inner nuclear layer
Internal limiting membrane is composed of which types of cells?
Footplates of Muller cells and their basal lamina
|»_space;Epi-retinal membranes usually occur in the ILM
What is the most common cell found in the retina and is exclusive to the retina?
Muller cells»they extend from the ELM to the ILM
|»_space;they help aid in glycogen metabolism
What is the main source of energy for the retina and how is it created?
Glucose that is formed through Anaerobic Glycolysis
Excess glucose is converted to glycogen and stored in ________ cells.
Muller cells
What role do neuroglial cells have in signal processing?
NONE»they provide protection and structural support to the retina.
The CRA forms two capillary networks formed in the ___ layer and the _______ layer of the retina.
NFL (superficial) and INL (deep network)
Inner retinal layers are drained by __________ vein.
central retinal vein
Outer retinal layers are drained by the __________ vein.
Vortex veins
In _________ part of the retina can be found all layers of the retina!
Parafoveal region!
What is the diameter of the macula? and where is it located in relation to the center of the optic disc?
5.5 mm diameter/ 3.5 mm lateral to the edge of the optic disc and 1 mm inferior to the center of the optic disc
What is the 2 major xanthophyll pigments responsible for reducing chromatic aberration and providing protection against free radicals?
Zeaxanthin and Lutein
What is the diameter of the Fovea? How large is the Foveola?
1.5 mm Fovea, 0.35 mm Foveola
What supplies the foveola with blood?
The underlying choriocapillaris via the SPCA’s
Which area of the retina is the thinnest?
Foveola–contains only cone photoreceptors»ganglion, bipolar, and other retinal cells displaced laterally in order to minimize light scattering
Where is the retina the thickest?
In the parafoveal region BECAUSE all retinal cells are laterally displaced from foveola to reduce light scattering
Which retinal layers are found within the Foveola?
RPE, PR layer, ELM, ONL, Henle’s fiber layer, and ILM
Henle’s Fiber Layer contains the ____________ of photoreceptors.
Axons
What is the Clivus in the parafovea?
It is the sloping of the retinal layers within the macula and marks the boundary between the para and the perifovea
What is the total diameter of the perifovea?
3.0 mm (1.5 mm zones)
In a CN X palsy, the uvula deviates _____the side of the lesion
AWAY»patient will report a hoarse voice
A CN XII palsy will result in tongue deviation ______ the side of the lesion.
TOWARDS
CN II fibers travel to one of three final destinations…
- LGN–relays info to V1 cortex
- Pretectal nucleus–pupil innervation
- Superior colliculus–saccadic control
The ______ fibers are the ONLY fibers from the sub-nuclei that decussate. A lesion of the right __ sub-nucleus will result in poor control of the left __ muscle.
Superior RECTUS!!!
> > MR, IR, IO project to the IPSILATERAL muscles and do not decussate
CN III fibers travel in close proximity to _________ artery as they exit the brainstem.
Posterior communicating artery (which is why it is most likely cause of CN III palsy)
Inferior division contains Parasympathetic fibers from Edinger-Westphal»ciliary ganglion; these fibers leave ganglion as __________________
SPCN’s and innervate the iris sphincter (3% fibers) and ciliary muscle (97% fibers)
The ____ and ____ are the only extraocular muscles that receive innervation from the Contralateral CN nuclei!
Superior Rectus and Superior Oblique
If a patient has damage to her right trochlear nucleus, which way will she tilt her head to try and minimize the effects?
Right trochlear nucleus will cause a LEFT superior oblique palsy…therefore, patient will tilt head to the RIGHT side
V1 ophthalmic division is divided into Nasociliary, Frontal, and Lacrimal nerves
»Which 5 nerves branch off of the nasociliary nerve?
LPCNs, SPCNs, infratrochlear, and anterior and posterior ethmoid nerves.
Which nerves branch off of the Frontal nerve?
Supratrochlear and Supraorbital nerves
What is the nerve supply to the Upper eyelid from lateral to medial?
Lacrimal»Supraorbital»Supratrochlear»Infratrochlear
Just before it enters the lacrimal gland, the lacrimal nerve receives ____________________ from the zygomatic branch of V2.
Parasympathetic fibers of CN VII
V2 divides into which two terminal branches?
- Infraorbital nerve
- Zygomatic nerve (which further divide into zygomaticofacial & zygomaticotemporal)»innervates LATERAL structures–lateral forehead, lateral cheek, and lateral lower eyelid.
»Remember, zygomatic carries Parasympathetic fibers from pterygopalatine ganglion of CN VII to the lacrimal nerve of V1 to stimulate lacrimation.
What is the nerve supply to the Lower eyelid?
zygomaticofacial»infraorbital»infratrochlear
What does V3 innervate?
- Provides sensory innervation to the lower face
2. Provides motor innervation to the muscles of mastication
What are two possible causes of CN VI palsy?
- Increased intracranial pressure compresses CN VI against petrous ridge, resulting in damage
- Internal carotid aneurysm due to close association between ICA and CN VI as they travel through the cavernous sinus
CN VII has 3 roots: 1. Voluntary motor root 2. Involuntary motor root and 3. Sensory root. What do these roots innervate?
- innervates facial muscles including orbicularis to close the eye
- Parasympathetic fibers stimulate secretion of facial glands, including lacrimation of lacrimal gland»also a branch to the stapedius muscle of middle ear to dampen sound
- Carries taste from anterior 2/3 of the tongue.
What does the greater petrosal nerve carry?
Parasympathetic innervation to the lacrimal gland»greater petrosal joins Deep petrosal to form the VIDIAN nerve»vidian travels to pterygopalatine where parasympathetic fibers synapse
»Post-ganglionic parasympathetic fibers leave pterygopalatine and join zygomatic branch of V2, which sends communicating branch to lacrimal nerve of V1 to innervate lacrimal gland
What role does Chorda Tympani nerve play in CN VII?
Carries taste fibers from anterior 2/3 of tongue
What are the 5 branches of the main root of CN VII and which 2 of these innervate muscles around the eye?
- Temporal»procerus, corrugator, frontalis, orbicularis oculi
- Zygomatic»orbicularis oculi
- Buccal
- Mandibular
- Cervical branches
Which gland innervates the parotid gland?
Glossopharyngeal nerve (CN IX)
Where would the lesion be if the patient has lower right facial paralysis, but upper frontal muscles are spared?
This would be a LEFT UPPER motor neuron lesion
If a patient has Bell’s palsy with the left facial muscles affected, which neurons are affected?
LOWER LEFT motor neurons would be impaired
What is the pathway for 1st, 2nd, and 3rd order neurons of the sympathetic system?
pre-ganglionic fibers begin in Hypothalamus, descent to C8-T2 spinal cord, which synapse in ciliospinal center of Budge.
»2nd order leave ganglion travel around clavicle across apex of lung»fibers ascend chain along the neck and synapse in superior cervical ganglion.
»Post-ganglionic fibers form plexus around ICA and enter skull via carotid canal.
Why are the disc margins blurred in Papilledema?
The CSF spreads over the margins into the surrounding RNFL»b/c the CSF within the subarachnoid space leaks over the superficial optic disc
What do Oligodendrocytes do?
Provide myelination to the axons posterior to the lamina cribrosa.
Why do people with optic neuritis experience pain on EOM’s?
The optic nerve sheath is attached to the sheaths surrounding the SR and MR muscles.
Which blood supplies the Intraocular ON (pre-laminar and laminary layers)?
Circle of Zinn (formed by anastomoses of SPCA’s)
Which blood supplies the Intraorbital ON (post-laminar)?
branches from the CRA and pial mater arterial plexus
Which blood supplies the Intracranial ON?
branches of ophthalmic,anterior, cerebral, ant. communicating, and ICA
Why does the optic nerve act as a blind spot?
There are NO PHOTORECEPTORS (only contains NFL and ILM)
Remember, there are NO MULLER CELLS over the optic disc. Therefore, _________ cover the optic disc and form the ILM of Elschnig.
Astrocytes
How long is the optic nerve?
50-60 mm long
How long is the Intraocular portion of the optic nerve?
1 mm»contains Pre-Laminar ON (tissue of Kuhnt, border tissue of Jacoby, border tissue of Elschnig) and Laminar ON
How long is the Intraorbital portion?
30 mm
How long is the Intracanclicular portion?
6-10 mm
How long is the Intracranial portion?
10-16 mm
___% optic nerve fibers synapse in the LGN before traveling to the visual cortex
90%
Fibers traveling to the superior colliculus aid in ____________________.
Saccadic eye movements
Fibers traveling to the pre-tectal nucleus aid in ________________.
Pupil involvement
Optic chiasm is located within the ______________. The pituitary gland is located __________ to the optic chiasm.
Circle of Willis; Inferior to the optic chiasm
What VF defects will occur with a Right anterior Knee of Wilbrand lesion?
Right central junctional scotoma, with a left superior temporal VF defect
Superior fibers synapse in the ________ LGN.
Medial
Inferior fibers synapse in the __________ LGN.
Lateral
Inferior optic radiations travel through the _______ lobe
Temporal lobe
Superior optic radiations travel through the inferior _______ lobe before terminating in VA.
Parietal lobe
What is the Cuneus gyrus?
Superior portion of V1 in the occipital lobe where superior fibers terminate
What is the Lingual gyrus?
Inferior portion of V1 in the occipital lobe where inferior retinal fibers terminate.
»Remember, Inferior retinal Fibers (LLLL)
Lower fibers, laterally, Meyers Loop, and Lingual gyrus
Binocular processing of visual information begins at the level of _____________.
Primary visual cortex (V1)
What happens in Layer 4 of visual cortex?
It is the location of synapses between the optic radiations and the neurons of the striate cortex
What happens in Layer 5 of visual cortex?
Sends axons to the superior colliculus for control of saccadic eye movements
What happens in Layer 6 of visual cortex?
Provides feedback information back to the LGN
The Primary visual cortex is supplied by the _____________ and _______________ artery.
Posterior cerebral and Middle cerebral arteries
Temporal lobe lesions cause _________ VF defects. This is often referred to as “___________”.
Superior VF defects, “Pie in the sky”
|»_space;inferior fibers forming Meyer’s loop are DAMAGED
Parietal lobe lesions cause _________ VF defects. This is often referred to as “___________”.
Inferior VF defects, “Pie on the floor”
|»_space;Superior fibers DAMAGED
The lacrimal gland is located in a bony fossa that is located… in what?
Located in the orbital surface of the frontal bone
Where is the sclera the thinnest?
Recti muscle insertions (NOT LAMINA CRIBROSA–this is the weakest place)
which 3 structures in the eye are responsible for glycogen storage?
Muller cells, Corneal epithelial cells, and vitreous humour
Which EOM is striated with multinucleated cells?
Superior oblique muscle
