A&P Eye Iris and Ciliary Body

very fast; sphincter

Parasympathetic innervation of the CB and iris have a (very slow/very fast) latency. This innervation innervates the iris (sphincter/dilator) muscle and innervates choroidal vessels.

1. Zonules
2. Vitreous base

The non-pigmented ciliary epithelium serves as an attachment site for what 2 structures?

iris

Found in anterior portion of globe that divides anterior and posterior chambers of anterior segment; anterior most part of uveal tract

collarette

Where is the thickest part of the iris?

iris root

Where is the thinnest part of the iris?

nasal; inferior

The pupil is slightly (nasal/temporal) and (superior/inferior) to dead center.

pupil

Controls amount of light let into the eye

Allows aqueous to flow from posterior to anterior chamber

Reduces spherical and chromatic abberation

Increases depth of focus

increases; reduces; increases

The pupil (increases/decreases) depth of focus. It also (increases/reduces) the extra light in photopic (bright) conditions and (increases/reduces) available light in scotopic (dark) conditions.

a. pupil and pupillary ruff

b. iris root

c. pupillary portion

d. ciliary portion

e. collarette

f. anterior border layer

g. stroma

h. iris sphincter muscle

i. posterior epithelium

j. anterior epithelium

k. anterior chamber angle

l. trabecular meshwork

m. Canal of Schlemm

n. ciliary bodt

Identify the following structures in the image of the iris.

collarette

Structure that divides the ciliary from the pupil portion of the iris

1. collarette
2. crypts
3. collarette
4. ruff

Identify the missing structures in the image (1-4).

pupillary zone

What structure within the iris is the red line pointing to?

collarette

What structure within the iris is the light blue line pointing to?

ciliary zone

What structure within the iris is the indigo line pointing to?

asymptomatic; abnormal collarette

Is the iris in the image asymptomatic or symptomatic? What abnormality is seen here?

1. Radial folds
2. Circular contraction folds

What are the 2 types of folds/wrinkles in the iris?

radial contraction furrows

What type of wrinkles in the iris are present on the posterior surface and run from the margin to the collarette?

radial structural furrows

What type of wrinkles in the iris are present on the posterior surface and run from the collarette, past the iris root, and into pars plicata?

Fuch’s crypts

What type of crypt is indicated by the pink circle?

Ciliary crypts

What type of crypt is indicated by the blue circle?

Fuch’s crypts

What type of crypt is deeper and allows aqueous into the stroma?

ciliary crypts

What type of crypt is smaller and is found in the ciliary zone?

trabeculae

Loosely arranged stroma connective tissue radial columns

pupillary ruff

Posterior pigmented epithelium that wraps around the anterior surface (brown fluff)

crenations

Lobules in the pupillary ruff; continuation of radial contraction furrows

1. Anterior border layer
2. Iris stroma/sphincter muscle
3. Anterior eptihelium/dilator muscle
4. Posterior pigment epithelium

List the four layers of the iris from front to back.

1. Melanocytes
2. Fibroblasts

What 2 types of cells made up the anterior border layer of the iris?

anterior border layer

Thin condensation of stroma (may not be a separate layer, not an epithelium)

Thickest at collarette, not present at the crypts

May form iris processes--attach to the trabecular meshwork

Ends at the root

Density of meshwork

What is the main influence of iris color?

Fibroblasts; melanocytes

What cells are present at the surface of the anterior border layer? Underneath the anterior border layer?

2-7 cells thick

How many cells thick is the anterior border layer?

iris nevus

Accumulation of melanocytes in anterior border layer

iris stroma

What layer of the iris is continuous with the stroma of the ciliary body & is HIGHLY vascular?

1. Collagen fibrils & ground susbtance
2. Pigmented cells
3. Non-pigmented cells
4. Vessels

What are the 4 main components of the iris stroma?

collagen fibrils & ground substance

What component of the iris stroma allows aqueous to flow within the stroma?

pigmented cells

What component of the iris stroma contain clump cells (large, round, dark) that are scavengers of free pigment and are usually found in the pupillary portion near the sphincter?

Non-pigmented cells

What component of the iris stroma involves fibroblasts, lymphocytes, macrophages, and mast cells?

1. Anterior border layer
2. Iris stroma
3. Sphincter muscle
4. Clump cell
5. Anterior iris epithelium
6. Posterior iris epithelium

Identify the structures in the image of the iris.

trabeculae

Collagen fibrils arranged in radial columns within the iris stroma

iris stroma

Which has less melanocytes & fibroblasts--the iris stroma or anterior border layer?

radially

Vessels that branch off of the major circle of the iris will run (radially/circularly) through the stroma.

iris stroma; pupillary region

What layer of the iris contains the iris sphincter muscle? In what region is the iris dilator muscle contained?

constriction

The iris sphincter muscle causes pupillary (dilation/constriction) in response to bright light or accommodation.

smooth muscle cells

What type of cells make up the iris sphincter muscle and are joined together by tight junctions?

parasympathetically; short

The iris sphincter muscle is (sympathetically/parasympathetically) innervated by the (long/short) ciliary nerves.

iris stroma & collagen around the iris dilator muscle

What is the iris sphincter firmly attached to?

False

True/False: The iris sphincter muscle cannot function with radial tears.

anteriorly

During contraction of the iris sphincter, the pupil margin pulls (posteriorly/anteriorly).

False

True/False: Anterior epithelium/iris dilator muscle is located on anterior iris.

anterior epithelium/iris dilator muscle

The ________________ layer of the iris is just anterior to the posterior epithelium.

myoepithelial cells

What type of cells make up the anterior epithelium/iris dilator muscle layer of the iris?

basal

The (apical/basal) side of the anterior epithelium/iris dilator muscle layer is anterior.

cuboidal pigmented epithelium; tight junctions & desmosomes

How would you classify the apical portion of cells in the anterior epithelium/iris dilator muscle layer? What joins these cells together?

Elongated, contractile smooth muscle processes

What composes the basal portion of the anterior epithelium/iris dilator muscle layer?

dilator

The iris (dilator/sphincter) is a poorly developed smooth muscle.

sympathetically; stroma

The iris dilator muscle is (sympathetically/parasympathetically) innervated and attaches to the _______ and some of the sphincter muscle.

3-5

Muscle fibers of the iris dilator muscle extends into the stroma, forming _____ layers.

anterior epithelium

What layer of the iris runs the whole length of the iris, is pigmented, but not as much as posterior epithelium, and continues posteriorly with pigmented epithelium of the ciliary body?

densely; larger

The posterior epithelium of the iris is (sparsely/densely) pigmented and contain (smaller/larger) cells than the anterior iris epithelium.

columnar

What are the shape of the posterior iris eptihelial cells?

tight junctions & desmosomes

What holds posterior epithelium cells together within the iris?

apical; desmosomes

The apical ends of the posterior epithelium faces the (apical/basal) ends of the anterior epithelium and is held together by _____________.

posterior

The basal side of the posterior epithelium faces the (anterior/posterior) chamber.

posterior

The (anterior/posterior) epithelium of the iris has a well-defined basement membrane.

radially; circularly

The iris dilator is (circularly/radially) oriented while the iris sphincter is (circularly/radially) oriented.

pigmented; posterior

In all individual (besides albanism) irises, the epithelial layers will be (non-pigmented/pigmented). The (posterior/anterior) epithelial layer is more so pigmented.

True

True/False: The number of melanocytes is fairly consistent between different eye colors.

False

True/False: The number of melanin granules within the melanocytes is fairly consistent between different eye colors.

1. Anterior border layer
2. Iris stroma

Most of the iris color is probably due to what 2 layers of the iris?

collagen trabeculae

What component of the iris is more apparent in lighter colored irises?

Shorter wavelengths are scattered more due to the arrangement and density of connective tissue.

What often causes lighter irises to appear blue?

Long wavelengths

In lighter irises, what wavelength of light is more absorbed?

albinism

Lack of pigment results in transillumination (light passes through)

Reduced acuity due in part to poorly functioning aperature

Heterochromia

Different color irises; melanocytes develop asymmetrically as babies mature

Can occur later due to injury, inflammation, etc.

ciliary body

Ocular structure that appears round when viewed from front to back

Middle portion of the uvea

Triangular in cross section

1. Ciliary stroma
2. Ciliary muscle
3. Supraciliaris
4. Pigmented epithelium
5. Nonpigmented epithelium
6. Pars plana
7. Pars plicata

Identify the structures of the ciliary body (1-7).

1. Accommodation
2. Production of aqueous humor
3. Contribution to vitreous production

What are the 3 main functions of the ciliary body?

1. Pars plana
2. Pars plicata

What are the 2 main parts of the ciliary body?

pars plana

Posterior flat part of the ciliary body

Meets the retina at the ora serrata

ora serrata; pars plicata

The pars plana extends from the _______ to the posterior edge of the ________________.

posteriorly; anteriorly

The pars plana thins (anteriorly/posteriorly) and thickens (anteriorly/posteriorly).

ciliary bays

Rounded edges of ciliary tissue

dentate processes

Tooth-like extensions of retina in between ciliary bays

striae ciliaris

Linear striations in the pars plana

Extends from the apex of dentate processes into the pars plicata

Site of attachments of initial fibers that coalesce to form ciliary zonules

pars plicata

Anterior portion of the ciliary body; contains the ciliary processes (70-80) and extends into the posterior chamber

Gets smaller with age

Valleys of Kuhnt

What lies between the pars plicata?

1. lens
2. ora serrata
3. sclera
4. ciliary process
5. pars plicata
6. pars plana

Identify the numbered structures in the image.

anteriorly; rounder; scleral spur; trabecular meshwork

During accommodation, the ciliary body shifts (posteriorly/anteriorly) and rotates outward slightly, allowing zonules to relax. This allows the lens to become more (flatter/rounder). This also pulls on the ______ and _______________, which can reduce intraocular pressure.

zonules

Fibers that suspend the lens in place

1. Pars plana
2. Valleys of pars plicata

What are the 2 locations in which zonules attach?

1\.5

Zonules start about ____ mm from the ora serrata.

1. Supraciliaris (supraciliary lamina)
2. Ciliary muscle
3. Ciliary stroma
4. Ciliary epithelia

List the 4 layers of the ciliary body from outer to inner.

1. Pigmented epithelium
2. Nonpigmented epithelium

What are the 2 sublayers of the ciliary epithelia layer of the ciliary body?

supraciliaris

What layer of the ciliary body is adjacent to the sclera, is the transition layer between the sclera & ciliary body, is continuous with the suprachoroid, and contains ribbon-like layers?

1. Melanocytes
2. Collagen bands
3. Fibroblasts

What are the 3 main components of the supraciliaris layer of the ciliary body?

lamina fusca

The supraciliaris merges with the __________ _________ of the sclera.

supraciliaris

What layer of the ciliary body allows the ciliary body to slide against the sclera without detaching/stretching (imp. for accommodation)?

supraciliaris

What layer of the ciliary body allows fluid into spaces?

1. Longitudinal
2. Radial
3. Circular

What are the 3 portions of the ciliary muscle?

scleral spur

All 3 portions of the ciliary muscle attach at the _________.