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.