30 Questions
From which embryonic layer does the optic cup develop?
Neuroectoderm
On which day does the lens development occur during embryonic development?
27th day
What forms the outer layer of the ciliary body and anterior iris epithelium?
Optic cup outer layer
Which structure replaces the pupillary membrane in the choroid?
Ciliary processes
What is the origin of the lens during embryonic development?
Surface ectoderm
What muscle is formed by the myofilaments of the anterior iris epithelium?
Iris sphincter muscle
What is the primary role of aqueous humor in the eye?
Maintaining the pressure and round shape of the globe in the anterior chamber
Which structure is responsible for the production and secretion of aqueous humor in the eye?
Non-pigmented ciliary epithelium
What is the composition of Bruch's membrane in the macula area?
5 layers: interrupted basement membrane of choriocapillaris, outer collagenous zone, elastic layer, inner collagenous zone, and basement membrane of RPE cells
Where does the uvea obtain its blood supply from?
Short posterior ciliary arteries around the optic nerve and long posterior ciliary arteries
What role does the choroid play in the eye?
Providing nutrients to the outer retina and absorbing excess light
Which structure is responsible for aqueous humor production and accommodation in the eye?
Ciliary body
When does the development of the vortex veins in the choroid occur?
6th month
From which layer does the outer layer of the optic cup develop?
Neuroectoderm
What is the function of the iris in the eye?
Allows light to enter the eye
How is the iris divided within the eye?
Divides into anterior and posterior segments
What separates the sphincter and dilator muscles in the iris?
Band of connective tissue
What is the composition of the uvea?
Iris, ciliary body, and choroid
What is the function of the ciliary muscle?
To control the shape of the lens for focusing
Which layer of the choroid is responsible for responding to both sympathetic and parasympathetic stimulation?
Choroidal stroma
What is the primary responsibility of the ciliary processes in the eye?
Production of aqueous humor
Where is the majority of the thickness of the ciliary body located?
Ciliary stroma
What is the main function of the choroid in the eye?
To provide nutrients to the outer retinal layers
What is the purpose of pericytes found in the choriocapillaris?
To alter local blood flow
What innervates the choroidal blood vessels for vasoconstriction?
Sympathetic fibers from the superior cervical ganglion
What is the condition where pigment granules are dispersed into the anterior chamber, compromising aqueous outflow?
Pigmentary dispersion syndrome
What is the primary innervation for ciliary muscle contraction?
Parasympathetic fibers from the ciliary ganglion
Which structure does Iris Synechia attach to?
Anterior lens surface
What is disrupted by inflammation of the uvea, resulting in Thyndall phenomenon, hyphema, or hypopion?
Aqueous humor
What is the primary element of the lens that acts as a barrier against large molecules?
Lens capsule
Study Notes
- The uvea is innervated by the trigeminal nerve (nasociliary) and the sympathetic and parasympathetic fibers.
- The sympathetic fibers from the superior cervical ganglion innervate the choroidal blood vessels for vasoconstriction. The long ciliary nerves innervate the iris dilation (contraction) and ciliary muscle relaxation.
- The parasympathetic fibers from the ciliary ganglion innervate the ciliary muscle contraction, iris sphincter muscle contraction, and choroidal vessels vasodilation.
- Age-related changes in the iris include loss of pigment from the epithelium at the pupillary margin, pigment deposition on the iris surface, anterior lens surface, posterior cornea, and trabecular meshwork, dilator muscle atrophy, and sphincter muscle becoming sclerotic.
- Age-related changes in the ciliary body include increasing sclerosis of the ciliary muscle, decreased ciliary muscle contraction, and decreased aqueous humor production.
- Age-related changes in the choroid include the presence of drusen, a decrease in choriocapillaris density and diameter, choroidal thickness, and the excessive deposition of basement membrane material.
- Iris Synechia is a condition where the iris attaches to another structure, either posteriorly to the anterior lens surface or anteriorly to the corneal epithelium or trabecular meshwork.
- Pigmentary dispersion syndrome is a condition where pigment granules are shed from the posterior iris surface and disperse into the anterior chamber, causing compromise of aqueous outflow and potentially increasing ocular pressure.
- The zonules, lens capsule, and lens undergo changes related to presbyopia.
- The aqueous humor can be disrupted by inflammation of the uvea, resulting in the Thyndall phenomenon, hyphema, or hypopion.
- Age-related macular degeneration is a condition where there is a degenerative process involving the choroid and retina, with the presence of multiple confluent drusen, detachment or atrophy of the retinal pigment epithelium, and subsequent loss of photoreceptors and neovascularization.
- Iris melanoma is a malignant tumor of the iris that can remain the same size and not significantly impair vision.
- Persistent pupillary membrane remnants are remnants of the pupillary membrane that should disappear around the sixth month of development.
- The posterior wall of the lens is columnar in shape, and the anterior wall of the lens is cuboidal.
- The fibers responsible for post-embryonic lens growth are secondary lens fibers.
- The primary lens fibers differentiate from the posterior lens epithelium in embryological development and form the embryonic lens nucleus, which disappears after birth.
- The anterior lens epithelium contains a germinative zone anterior to the equator, cuboidal cells, and becomes fetal nucleus and secretes the anterior capsule throughout life.
- The lens growth after embryonic development is attributed to secondary lens fibers.
- The lens is neither vascular nor transparent.
- The lens consists of three parts: the capsule, lens epithelium, and lens fibers.
- The lens capsule is an elastic, acellular layer that acts as a barrier against large molecules and has a thickness that varies in different regions.
- The thickest region of the lens capsule is in the anterior and posterior regions of the equator.
- The lens capsule is the extracellular matrix base membrane of the whole body.
Test your knowledge of the anatomy of the ciliary body with this quiz. Explore the structure, function, and features of the ciliary body including its posterior area, anterior ciliary processes, and the parts known as pars plana and pars plicata.
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