36 Questions
What is the location of the scleral spur?
At the posterior edge of the internal scleral sulcus
What is the function of the trabecular meshwork and Schlemm's canal?
Filtration of aqueous humor
What is the term for the system of fine fibrils connecting the cribriform plexus to the inner wall endothelium and the plaque material?
Connecting fibrils
What is the orientation of the elastic-like fibers of the trabecular lamellas?
Equatorial
What is the region where the ciliary muscle tendons attach?
Posterior portion of the internal scleral sulcus
What is the layer where the cribriform plexus is mainly located?
Region between the first and second subendothelial cell layers
What is the main component of the limbal stroma?
Scleral and corneal tissues
What is the function of the vessels forming the intrascleral plexus?
To drain aqueous humor from the eye
What is the term for the spaces between the trabecular meshwork sheets?
Intertrabecular spaces
Which part of the trabecular meshwork has the smallest pores?
Juxtacanalicular meshwork
What is the purpose of the ciliary muscle tendons?
To connect the ciliary muscle to the trabecular meshwork
What is the term for the termination of Descemet's membrane?
Schwalbe's line
What is the main component of Tenon's capsule?
Loose connective tissue
What is the function of the conjunctival stromal vessels?
To form the peripheral corneal arcades
What is the term for the region of the trabecular meshwork that attaches to the scleral spur?
Corneoscleral meshwork
What is the purpose of the iris process?
To connect the iris to the trabecular meshwork
What is the main function of the canal of Schlemm?
To drain aqueous humor from the eye
What type of fibers are found in the juxtacanalicular connective tissue region?
Collagen and elastic-like fibers
What is the purpose of the aqueous humor flow pathway?
To regulate intraocular pressure
What percentage of aqueous humor flows through the uveal meshwork?
5-35%
What is the term for the spaces within the uveal meshwork?
Large-size pores
What is the name of the vessels that drain directly into the episcleral veins?
Aqueous veins of Ascher
What is the purpose of the giant vacuoles in the endothelial cells lining the canal of Schlemm?
To facilitate passive diffusion
What is the name of the structure that separates the endothelial cell lining of the canal of Schlemm from the trabecular meshwork?
Juxtacanalicular connective tissue region
What is the name of the space that exists between the iris and lens?
Posterior chamber
What is the main route of aqueous humor outflow from the anterior chamber?
Through the trabecular meshwork and Schlemm's canal
What is the main function of the aqueous humor?
To carry away waste products of the lens and cornea
What is the normal resistance to aqueous passage through the trabecular meshwork?
Low resistance
Where is the location of higher resistance to aqueous movement?
Juxtacanalicular tissue and endothelium of the inner wall of Schlemm's canal
What percentage of the outflow resistance is at the juxtacanalicular tissue?
75%
What is the average intraocular pressure (IOP)?
15.5 mmHg
What is the effect of diabetes on the eye?
Neovascularization from proliferative diabetic retinopathy
What is the effect of uveitis on the eye?
Inflammation of the uveal tract
What is the effect of Fuch's endothelial dystrophy on the eye?
Chronic dystrophy leading to permanent damage to the trabecular meshwork
What is the effect of pseudoexfoliative glaucoma on the eye?
Aging epithelial cells of the iris and lens capsule releasing pigment and pseudoexfoliative material
What is the effect of pigment dispersion glaucoma on the eye?
Pigment liberated from the posterior layer of the iris causing damage to the trabecular fibrils
Study Notes
Anterior Chamber Angle Structures
- Located at the internal scleral sulcus (corneoscleral junction)
- Consists of:
- Trabecular Meshwork
- Schlemm’s canal (both part of the filtration apparatus)
- Scleral spur
Scleral Spur
- Lies at the posterior edge of the internal scleral sulcus
- Posterior portion: longitudinal ciliary muscle fibers attach
- Anterior portion: many trabecular sheets attach
Trabecular Meshwork
- Occupies most of the inner aspect of the internal scleral sulcus
- Triangular shape: apex at Schwalbe’s line (termination of Descemet’s membrane), base at the scleral spur
- Composed of:
- Flattened, perforated sheets of collagen and elastic fibers embedded in ground substance
- Covered by basement membrane and endothelium
- 3-5 sheets at the apex, branching into 15-20 sheets posteriorly
- Intertrabecular spaces between the sheets connected through pores (“spaces of Fontana”)
- Divided into three anatomic divisions:
- Uvealmeshwork (inner sheets attaching to ciliary stroma and longitudinal muscle fibers)
- Corneoscleralmeshwork (outer region attaching to the scleral spur)
- Juxtacanalicularmeshwork (connective tissue surrounded by endothelium)
Schlemm's Canal
- Circular vessel considered to be a venous channel (contains aqueous humor instead of blood)
- Lumen lined with endothelial cells joined by zonula occludens
Aqueous Humor Dynamics
- Produced in the pars plicata of the ciliary body
- Secreted to the posterior chamber through the non-pigmented ciliary epithelium
- Passes between the iris and lens, entering the anterior chamber through the pupil
- Circulates in convection currents in the anterior chamber
- Exits through the periphery of the chamber
- Two main exit routes:
- Unconventional outflow (5-35%): through the spaces within the uveal meshwork, into connective tissue spaces surrounding the ciliary body muscle bundles, and absorbed into the sclera or anterior ciliary veins
- Conventional outflow pathway: through the uveal meshwork, corneoscleral meshwork, and juxtacanalicular tissue, entering Schlemm's canal
Aqueous Humor Outflow
- Regulated by the balance between production and exit
- Maintained within a small range by the complex equilibrium between production and exit
- Most cases of increased IOP are caused by decreased aqueous outflow
- Resistance to aqueous outflow located in the juxtacanalicular tissue (JCT) and the endothelium of the inner wall of Schlemm's canal
Learn about the structures located at the internal scleral sulcus, including the Trabecular Meshwork, Schlemm's canal, and Scleral spur. Understand their functions and relationships in the filtration apparatus.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
