Notes in 14Eye

To Subscribe, use this Key

Status	Last Update	Fields
Published	07/30/2024	Diameter of the eye
Published	07/30/2024	Only the {{c1::anterior one sixth::direction and fraction}} of the eye’s surface is visible
Published	07/30/2024	Only the anterior onesixth of the eye’s surface is visible; the rest of the eye lies in the cone-shaped bony {{c1::orbit}}
Published	07/30/2024	The eye in the orbit is surrounded by
Published	07/30/2024	Which half of the orbit contains the optic nerve, the arteries and veins to the eye, and the extrinsic eye muscles.
Published	07/30/2024	The {{c1::eyebrows}} consist of coarse hairs in the skin on the {{c2::superciliary arches}}
Published	07/30/2024	Anteriorly, the eyes are protected by the mobile {{c1::eyelids}}, or {{c1::palpebrae (pal′pe˘-bre)}}.
Published	07/30/2024	The upper and lower lids are separated by the {{c1::palpebral fissure (eye slit)}} and meet each other at the {{c2::medial and lateral angles (eye cor…
Published	07/30/2024	The {{c1::medial}} angle contains a reddish elevation called the {{c2::lacrimal caruncle}}
Published	07/30/2024	In most Asian people, a vertical fold of skin called the {{c1::epicanthic fold}} occurs on both sides of the nose and sometimes covers the {{c2::media…
Published	07/30/2024	The eyelids are thin, skin-covered folds supported internally by connective tissue structures called {{c1::tarsal plates}}
Published	07/30/2024	These stiff {{c2::tarsal plates}} give the eyelids their curved shape and serve as attachment sites for the eye-closing muscle, the {{c1::orbicularis …
Published	07/30/2024	The {{c1::levator palpebrae superioris (“lifter of the upper eyelid”)}} is the skeletal muscle that voluntarily opens the eye.
Published	07/30/2024	The {{c1::levator palpebrae superioris}} runs {{c2::anteriorly}} from the {{c3::posterior roof}} of the orbit, enters the upper eyelid, and inserts on…
Published	07/30/2024	The {{c1::inferior::inferior/superior}} part of the aponeurosis of the {{c2::levator palpebrae superioris}} contains fibers of smooth muscle, cal…
Published	07/30/2024	Projecting from the free margin of each eyelid are the {{c1::eyelashes}}.
Published	07/30/2024	Because the {{c2::follicles of these eyelash hairs}} are richly innervated by nerve endings, even slight pressure on the eyelashes will trigger {{c1::…
Published	07/30/2024	{{c1::Tarsal glands}} are modified sebaceous glands embedded in the {{c2::tarsal plates}}
Published	07/30/2024	About {{c1::25::number}} of these vertical {{c2::Tarsal}} glands line up side by side in the upper eyelid; {{c3::fewer::more/fewer}} than this li…
Published	07/30/2024	The tarsal gland ducts open along the edge of the {{c1::eyelids}}.
Published	07/30/2024	These {{c1::ciliary glands (cilium = eyelash)}} include {{c2::typical sebaceous}} glands whose ducts open into the {{c2::hair follicles}}, and {{c3::m…
Published	07/30/2024	Infection of a tarsal gland results in an unsightly cyst called a {{c1::chalazion (kah-la′ze-on; “swelling”)}}
Published	07/30/2024	infection of the ciliary glands is called a {{c1::sty}}.
Published	07/30/2024	The {{c1::conjunctiva (con″junk-ti′vah; “joined together”)}} is a transparent mucous membrane that covers the inner surfaces of the eyelids as the {{c…
Published	07/30/2024	The {{c1::bulbar conjunctiva}}, which covers the white of the eye but not the cornea, is a very thin membrane, and blood vessels are {{c2::clearly::cl…
Published	07/30/2024	Does the bulbar conjuctiva cover the cornea?
Published	07/30/2024	When an eye is closed, the slitlike space that forms between the eye surface and the eyelids is the {{c1::conjunctival sac}}.
Published	07/30/2024	Where would a contact lens lie
Published	07/30/2024	Microscopically, the conjunctiva consists of a {{c1::stratified columnar}} epithelium underlain by a thin {{c1::lamina propria}} of loose connect…
Published	07/30/2024	The conjuctiva epithelium contains scattered {{c1::goblet}} cells that secrete a lubricating mucus that prevents the eyes from drying.
Published	07/30/2024	A deficiency of vitamin {{c1::A}}, a vitamin required for maintaining epithelia throughout the body, prevents the conjunctiva from secreting mucus. As…
Published	07/30/2024	Inflammation of the conjunctiva, called {{c1::conjunctivitis}}, is a relatively common condition. {{c1::Conjunctivitis}} irritates the eyes and makes …
Published	07/30/2024	The {{c1::lacrimal apparatus (lak′r˘ı-mal; “tear”)}}, which keeps the surface of the eye moist with lacrimal fluid (tears), consists of a gland and du…
Published	07/30/2024	The {{c1::lacrimal gland}}, lying in the {{c2::orbit::cavity}} {{c2::superolateral::direction}} to the eye, produces lacrimal fluid, which enters the …
Published	07/30/2024	Blinking the eye spreads this fluid {{c1::inferiorly::direction}} across the eyeball to the {{c2::medial angle}}.
Published	07/30/2024	At the {{c1::medial angle}}, each lid contains a tiny opening called the {{c2::lacrimal punctum (“puncture”)}} which empties into a small tube, the {{…
Published	07/30/2024	From the lacrimal punctum and lacrimal canaliculus, the fluid drains into the {{c1::lacrimal sac}} in the {{c2::medial::direction}} {{c2::orbital…
Published	07/30/2024	Tears enter the {{c1::nasolacrimal duct}}, which empties into the nasal cavity at the {{c2::inferior nasal meatus}}.
Published	07/30/2024	Lacrimal fluid contains mucus, antibodies, and {{c1::lysozyme}}, an enzyme that destroys bacteria.
Published	07/30/2024	{{c1::Six::number}} straplike {{c2::extrinsic (outer)::extrinsic/intrinsic}} eye muscles which originate from the walls of the orbit and insert onto t…
Published	07/30/2024	{{c2::Four}} of the extrinsic eye muscles are {{c1::rectus}} muscles.
Published	07/30/2024	Rectus muscles originate from the {{c1::common tendinous ring, or anular ring}}, at the {{c2::posterior::location}} point of the orbit.
Published	07/30/2024	{{c3::lateral rectus}} muscle turns the eye {{c1::laterally (outward)}}{{c3::medial rectus}} muscle turns it {{c1::medially (inward)}}{{c4::superior r…
Published	07/30/2024	The {{c1::superior oblique}} muscle originates {{c2::posteriorly::direction}} near the common tendinous ring, runs {{c3::anteriorly::direction}} along…
Published	07/30/2024	The superior oblique muscle tendon runs {{c2::posteriorly::direction}} from the trochlea and inserts on the eye’s {{c1::posterolateral::location}} sur…
Published	07/30/2024	the {{c2::superior oblique}} {{c1::depresses}} the eye and turns it {{c1::laterally}} {{c1::(down and out)}}
Published	07/30/2024	The {{c1::inferior oblique muscle}} originates on the {{c2::anteromedial::location}} part of the orbit floor and angles back to insert on the {{c3::po…
Published	07/30/2024	The {{c2::inferior oblique}} {{c1::elevates}} the eye and turns it somewhat {{c1::laterally (up and out).}}
Published	07/30/2024	The superior oblique is controlled by CN {{c1::IV}}
Published	07/30/2024	In {{c1::strabismus}}, the affected eye is turned either medially or laterally with respect to the normal eye from weakness or paralysis of extrinsic …
Published	07/30/2024	What is the conjunctiva, and where is it located?
Published	07/30/2024	What muscle is not functioning in a person whose eye turns medially? What nerve innervates this muscle?
Published	07/30/2024	The eye's most anterior point is the {{c1::anterior pole}}, and its most posterior point is the {{c1::posterior pole}}.
Published	07/30/2024	The eye's external wall consists of {{c1::three}} layers, and its internal cavity contains fluids called {{c1::humors}}.
Published	07/30/2024	The {{c1::lens}}, a structure that helps to focus light, is supported vertically within the internal cavity, dividing it into {{c2::anterior}} and {{c…
Published	07/30/2024	The {{c1::anterior segment}} is filled with the {{c2::liquid aqueous humor::adjective and noun}}, whereas the {{c1::posterior segment}} is filled with…
Published	07/30/2024	Three layers form the external wall of the eye: the {{c1::fibrous}} layer, the {{c1::vascular}} layer, and the {{c1::sensory/retina}} layer.
Published	07/30/2024	The fibrous layer is the most {{c1::external::external/internal}} layer. It consists of {{c1::dense connective}} tissue arranged into two different re…
Published	07/30/2024	The opaque white, tough {{c1::sclera}} forms the {{c2::posterior five-sixths::location and fraction}} of the fibrous layer. Seen anteriorly as the “wh…
Published	07/30/2024	The {{c1::anterior sixth::location and fraction}} of the fibrous layer is the transparent {{c2::cornea}}, through which light enters the eye. This rou…
Published	07/30/2024	The {{c1::cornea}} consists of a thick layer of {{c2::dense connective}} tissue sandwiched between a {{c3::superficial corneal epithelium}} and a {{c3…
Published	07/30/2024	At the junction of the {{c1::cornea}} and {{c1::sclera}}, between the {{c1::corneal epithelium}} and the {{c1::conjunctiva}}, are {{c2::epithelial ste…
Published	07/30/2024	The cornea is {{c1::avascular::avascular/vascular}}
Published	07/30/2024	The cornea receives oxygen from the {{c1::air in front of it}}, and oxygen and nutrients from the {{c1::aqueous humor that lies posterior to it.}}
Published	07/30/2024	The cornea is richly supplied with nerve endings, most of which are {{c1::pain receptors}}. Touching the cornea causes {{c2::reflexive blinking}} and …
Published	07/30/2024	In the 10% of transplanted corneas that are rejected, the damage to the recipient’s original cornea was so extensive that it destroyed the {{c1::corne…
Published	07/30/2024	The {{c1::vascular layer}}, the middle coat of the eyeball, has three parts: the {{c2::choroid}}, the {{c2::ciliary body}}, and the {{c2::iris}}
Published	07/30/2024	The {{c1::choroid (ko′roid; “membrane”)}} is a highly vascular, darkly pigmented membrane that forms the {{c2::posterior fivesixths::location and frac…
Published	07/30/2024	The fibrous layer gets its nourishment from the {{c1::vascular layer}}
Published	07/30/2024	The brown color of the choroid is produced by {{c1::melanocytes}}, whose pigment, {{c1::melanin}}, helps absorb light, thereby preventing light from s…
Published	07/30/2024	Anteriorly, the choroid is continuous with the {{c1::ciliary body}}, a thickened ring of tissue that encircles the lens.
Published	07/30/2024	The ciliary body consists chiefly of smooth muscle called the {{c1::ciliary muscle}}, which acts to focus the lens.
Published	07/30/2024	Nearest the lens, the posterior surface of the ciliary body is thrown into radiating folds called {{c1::ciliary processes}}.
Published	07/30/2024	The halo of fine fibrils that extends from around the entire circumference of the lens and attaches to the ciliary processes is called the {{c1::cilia…
Published	07/30/2024	The {{c1::iris (“rainbow”)}} is the visible, colored part of the eye. It lies between the {{c2::cornea}} and {{c2::lens}}, and its base attaches to th…
Published	07/30/2024	The Iris's round central opening, the {{c1::pupil}}, allows light to enter the eye.
Published	07/30/2024	The iris contains both circularly arranged and radiating smooth muscle fibers, the {{c1::sphincter}} and {{c1::dilator pupillae}} muscles, that act to…
Published	07/30/2024	In bright light and for close vision, the {{c1::sphincter pupillae}} contracts to constrict the pupil. In dim light and for distant vision, the {{c1::…
Published	07/30/2024	Although irises come in many colors, they contain only {{c1::brown pigment}}. All people except albinos have a layer of pigmented cells on the {{…
Published	07/30/2024	The inner layer contains the {{c1::retina}} and the {{c1::optic nerve}}.
Published	07/30/2024	The retina consists of two layers: a {{c1::thin pigmented layer::adjective and noun}} and a {{c2::far thicker neural layer::adjective and noun}}
Published	07/30/2024	The outer pigmented layer of the retina, which lies against the {{c1::choroid}}, is a single layer of {{c2::flat-to-columnar melanocytes}}.
Published	07/30/2024	The much thicker inner neural layer of the retina is a sheet of nervous tissue that contains the {{c1::light-sensitive photoreceptor cells}}.
Published	07/30/2024	The neural and pigmented layers of the retina are held together by a thin film of {{c1::extracellular matrix}}, but they are not tightly fused. Only t…
Published	07/30/2024	The {{c1::pigmented}} layer supports the photoreceptive cells by removing damaged portions of those cells, maintaining the proper ionic concentration …
Published	07/30/2024	The neural layer contains three main types of neurons. From external to internal, these are the {{c1::photoreceptor}} cells, {{c1::bipolar}} cells, an…
Published	07/30/2024	Axons from the ganglion cells run along the internal surface of the retina and converge posteriorly to form the {{c1::optic}} nerve
Published	07/30/2024	The retina also contains {{c1::interneurons}}—including {{c1::amacrine}} cells and {{c1::horizontal}} cells—that process and modify visual information…
Published	07/30/2024	The photoreceptor cells are of two types: {{c1::rod}} cells and {{c1::cone}} cells.
Published	07/30/2024	The more numerous {{c1::rod}} cells are more sensitive to light and permit vision in dim light. Because {{c1::rod}} cells provide neither sharp images…
Published	07/30/2024	{{c1::Cone}} cells operate best in bright light and enable high-acuity color vision. Three subtypes of {{c1::cone}} cells are sensitive to blue, red, …
Published	07/30/2024	Photoreceptor cells are considered neurons, but they also resemble tall epithelial cells turned upside down, with their “tips” immersed in the {{c1::p…
Published	07/30/2024	Both rod cells and cone cells have an {{c1::outer}} segment joined to an {{c1::inner}} segment by a connecting {{c1::cilium}}.
Published	07/30/2024	In each rod cell, the inner and outer segments together form a rodshaped structure, which connects to the nucleus-containing cell body by an {{c1::out…
Published	07/30/2024	{{c1::cone}} photoreceptor cells do not have an outer fiber connecting the rod/cone to the soma
Published	07/30/2024	The {{c1::outer::outer/inner}} segments are the receptor regions of the rod and cone cells. Each {{c2::outer::outer/inner}} segment is a modified cili…
Published	07/30/2024	Photoreceptor cells {{c1::cannot::can/cannot}} regenerate if destroyed
Published	07/30/2024	In the anterior part of the eye, the neural layer ends at the posterior margin of the {{c1::ciliary body}}. This junction is called the {{c2::ora serr…
Published	07/30/2024	The pigmented layer extends anteriorly beyond the {{c1::ora serrata}} to cover the ciliary body and to form the pigmented layer of the posterior iris.
Published	07/30/2024	Lying precisely at the eye’s posterior pole is the {{c1::macula lutea}}
Published	07/30/2024	At the center of the macula lutea is a tiny pit called the {{c1::fovea centralis}}
Published	07/30/2024	The fovea contains only {{c1::cones}} and provides maximal visual acuity
Published	07/30/2024	A few millimeters {{c1::medial::location}} to the fovea is the {{c2::optic disc}}
Published	07/30/2024	The optic disc is called the {{c1::blind spot}} because it lacks photoreceptors, and light focused on it cannot be seen.
Published	07/30/2024	{{c1::Age-Related Macular Degeneration (AMD)}} is a progressive deterioration of the retina that affects the macula lutea and leads to loss of central…
Published	07/30/2024	two forms of age-related macular degeneration
Published	07/30/2024	Which for of AMD can be treated with injections of laser treatments that destroy the growing vessels
Published	07/30/2024	{{c1::Dry AMD}} involves the buildup of visual pigments in the macula caused by loss of cells in the pigmented layer of the retina that normally remov…
Published	07/30/2024	The retina receives its blood from {{c1::two::number}} different sources
Published	07/30/2024	The {{c1::outer third::location and fraction}} of the retina, containing the photoreceptors, is supplied by capillaries in the choroid, whereas its {{…
Published	07/30/2024	The retina’s pattern of vascularization contributes to a potentially blinding condition called {{c1::retinal detachment}}, in which the loosely joined…
Published	07/30/2024	Early symptoms of {{c1::retinal detachment}} include seeing flashing lights or spots that float across the field of vision, and having objects appear …
Published	07/30/2024	The lens and its halolike ciliary zonule divide the eye into {{c1::posterior}} and {{c1::anterior}} segments
Published	07/30/2024	The {{c1::posterior}} segment is filled with the clear {{c2::vitreous humor (vitreus = glassy)}}, a jellylike substance that contains fine fibrils of …
Published	07/30/2024	The vitreous humor functions to:1. {{c1::Transmit light}}2. {{c1::Support the posterior surface of the lens and hold the neural retina firmly against …
Published	07/30/2024	The {{c1::anterior}} segment of the eye is divided into an {{c2::anterior}} chamber between the {{c2::cornea}} and {{c2::iris}}, and a {{c2::posterior…
Published	07/30/2024	The entire anterior segment is filled with {{c1::aqueous humor}}, a clear fluid similar to blood plasma
Published	07/30/2024	Unlike the {{c1::vitreous}} humor, which forms in the embryo and lasts a lifetime, {{c1::aqueous}} humor is renewed continuously and is in constant mo…
Published	07/30/2024	After being formed as a filtrate of the blood from capillaries in the ciliary processes, the aqueous humor enters the posterior chamber, flows through…
Published	07/30/2024	Furthermore, the aqueous humor supplies nutrients and oxygen to the avascular {{c1::lens}} and {{c2::cornea}}
Published	07/30/2024	When the aqueous humor drains more slowly than it forms, the result is {{c1::glaucoma (glaw-ko′mah)}}, a disease in which intraocular pressure increas…
Published	07/30/2024	Late signs include blurred vision, seeing halos around lights, and headaches.
Published	07/30/2024	The {{c1::lens}} is a thick, transparent, biconvex disc that changes shape to allow precise focusing of light on the retina. It is enclosed in a thin …
Published	07/30/2024	The lens has two components: the {{c1::lens epithelium}} and the {{c1::lens fibers}}.
Published	07/30/2024	The {{c1::lens epithelium}}, confined to the {{c2::anterior}} surface, consists of {{c3::cuboidal}} cells.
Published	07/30/2024	The subset of epithelial cells around the edge of the lens disc transforms continuously into the elongated {{c1::lens fibers}} that form the bulk of t…
Published	07/30/2024	{{c1::cataract}} is a clouding of the lens that causes the world to appear distorted, as if seen through frosted glass.
Published	07/30/2024	Differentiate the cornea from the choroid with reference to the location, structure, and function of each.
Published	07/30/2024	What portion of the visual field is lost in a person with degeneration of the macula lutea (macular degeneration)?
Published	07/30/2024	What is the aqueous humor, where is it located, and what are its functions?
Published	07/30/2024	If one is to see clearly, the eye must be able to bend all these light rays so that they converge on the retina at a single {{c1::focal}} point
Published	07/30/2024	The light-bending parts of the eye, called {{c1::refractory media}}, are the {{c2::cornea}}, the {{c2::lens}}, and the {{c2::humors}}.
Published	07/30/2024	Although the lens is not as powerful as the cornea in bending light, its curvature is adjustable. This adjustability allows the eye to focus on nearby…
Published	07/30/2024	Therefore, {{c1::distance::distance/near}} vision is the natural state
Published	07/30/2024	Accommodation is controlled by the {{c1::parasympathetic}} fibers that signal the ciliary muscle to contract.
Published	07/30/2024	Focusing on nearby objects is accompanied by pupillary {{c1::constriction::constriction/dilation}}
Published	07/30/2024	Distant vision requires {{c1::flattening}} of the lens and ciliary {{c2::relaxation}}
Published	07/30/2024	Near vision requires {{c1::bulging}} of the lens and ciliary {{c2::contraction}}
Published	07/30/2024	{{c1::Myopia}}, commonly referred to as nearsightedness, occurs when the shape of the eye or the bending of the lens results in a focal point for dist…
Published	07/30/2024	{{c1::Hyperopia, or farsightedness}}, results when the eye is {{c2::short}}, causing the focal point to occur {{c3::behind}} the retina. For viewing d…
Published	07/30/2024	VIsual Pathway to the Cerebral Cortex
Published	07/30/2024	Which axons of the eye decussate at the optic chiasma? (lateral/medial)
Published	07/30/2024	The partial decussation of axons in the optic chiasma relates to depth perception, which is also called {{c1::stereoscopic, or three-dimensiona}}l, vi…
Published	07/30/2024	information from the {{c1::left}} half of the visual field is directed through the {{c2::right}} optic tract to be perceived by the {{c3::right}} cere…
Published	07/30/2024	Some axons from the optic tracts send branches to the midbrain. These branches go to the {{c1::superior colliculi}}, reflex nuclei controlling th…
Published	07/30/2024	The eyes develop as outpocketings of the brain. By week 4, paired lateral outgrowths called {{c1::optic vesicles}} protrude from the {{c2::diencephalo…
Published	07/30/2024	Once a growing optic vesicle reaches the overlying surface ectoderm, it signals the ectoderm to thicken and form a {{c1::lens placode}}. By week 5, th…
Published	07/30/2024	The {{c2::internal}} layer of the optic cup differentiates into the {{c1::neural retina}}, whereas the {{c3::external}} layer becomes the {{c4::pigmen…
Published	07/30/2024	The {{c1::optic fissure}}, a groove on the underside of each {{c2::optic stalk and cup}}, serves as a direct pathway for blood vessels to reach and su…
Published	07/30/2024	The fibrous layer, vascular layer, and vitreous humor form from n{{c1::eural-crest-derived head mesenchyme}} that surrounds the early {{c2::optic cup}…
Published	07/30/2024	When the infant is weaned from the high concentrations of oxygen, new blood vessels start to grow extensively within the eyes. These abnormal vessels …
Published	07/30/2024	{{c1::Trachoma (trah-ko′mah; “rough growth”)}} is a highly contagious infection of the conjunctiva and cornea, caused by the bacterium Chlamydia trach…
Status	Last Update	Fields