Lecture 9: 12/14

Question 1

what are the two zones on the anterior surface of the iris

Answer 1

1. central pupillary zone

2. peripheral ciliary zone

Question 2

junction between the 2 zones of the iris is called

Answer 2

the collarette

Question 3

the collarette is the thickest part of the iris and is _____ thick

Answer 3

0.6mm thick

Question 4

appearance and location of the collarette

Answer 4

a zigzag, circular ridge easily seen about 1.5mm peripheral to the pupillary margin

Question 5

explain the pupillary ruff

Answer 5

an extension of the two posterior epithelial layers which folds up around the pupillary margin and is visible as a heavily pigmented border

Question 6

the three areas of the ciliary zone

Answer 6

• an inner area adjacent to the collarette
• a furrowed central area
• a marginal cribiform area next to the ciliary body

Question 7

the dark pits that appear to go deep into the iris are called

Answer 7

Fuch’s crypts

Question 8

Fuch’s crypts are adjacent to the _____ and are the result of _____

Answer 8

adjacent to the collarette and result of the erosion

Question 9

the marginal cribriform area (most peripheral) can be seen only with what equipment?

Answer 9

ginioscopy

Question 10

what are two things unique about the marginal cribriform area?

Answer 10

• small little crypts called ciliary crypts

- iris pectinate fibers seen in this area

Question 11

what is special about the central area (furrowed zone) of the ciliary zone?

Answer 11

there are contraction furrows that run concentric with the pupil

Question 12

what is found in the inner area of the ciliary zone?

Answer 12

smooth, slight radial ridges

Question 13

what are the three types of zones/furrows on the posterior surface of the iris?

Answer 13

1. contraction folds of Schwalbe
2. circular folds
3. structural folds of Schwalbe

Question 14

the contraction folds of Schwalbe are:

Answer 14

grooves that run from the pupillary margin peripherally to the collarette

Question 15

circular folds are:

Answer 15

concentric around the pupil

Question 16

radial folds (most peripheral) run

Answer 16

radially on in to the ciliary body, are valleys between ciliary processes

Question 17

4 layers of the iris, from anterior to posterior

Answer 17

1. anterior limiting layer
2. stroma
3. posterior membrane (anterior epithelium)
4. posterior pigmented epithelium

Question 18

what 2 iris layers were derived from mesoderm?

Answer 18

• anterior limiting layer

- stroma

Question 19

what 2 iris layers were derived from neuro-ectoderm?

Answer 19

• posterior membrane (anterior epithelium)

- posterior pigmented epithelium

Question 20

what layer of the iris is a big determinant in the color of the iris?

Answer 20

anterior limiting layer

Question 21

which layer of the iris is absent or thinned at the crypts?

Answer 21

anterior limiting layer

Question 22

2 main cell types in the anterior limiting layer of the iris?

Answer 22

• fibroblasts

- melanocytes

Question 23

location of the fibroblasts in the anterior limiting layer of the iris

Answer 23

from the most anterior layer, located root to margin

Question 24

location of the melanocytes of the anterior limiting layer of the iris

Answer 24

posterior, pigment cells with have “arms” that tend to connect with each other

Question 25

are capillaries present in the anterior limiting layer of the iris and if so, how dense?

Answer 25

yes they are common and may increase in size and number in response to pathologies such as iritis and diabetes

Question 26

the layer of the iris that is loosely arranged collagenous connective tissue network which comprises most of the thickness of the iris

Answer 26

stroma

Question 27

list some important structures embedded in the stroma layer of the iris

Answer 27

blood vessels and nerves, pigmented (melanocytes) and unpigmented (fibroblast) cells, sphincter muscle

Question 28

sphincter muscle width (cross section) is _____ mm

Answer 28

0.75 mm

Question 29

location and action of the sphincter muscle

Answer 29

it is a flat muscle that runs radially around the pupil | -when it contracts, it makes the pupil smaller

Question 30

the sphincter muscle is bound firmly on its posterior side to:

Answer 30

to a layer of connective tissue which is continuous with the dilator muscle

Question 31

what is the sphincter muscle composed of and what is it innervated by?

Answer 31

the sphincter is composed of smooth muscle cells and is supplied by parasympathetic nerve fibers in the short ciliary nerves

Question 32

blood vessels of the iris reside in the ______

Answer 32

stroma

Question 33

blood vessels enter the iris from the :

Answer 33

major arterial circle of iris

Question 34

at the region of the collarette the arteries form an incomplete circular anastomosis called the:

Answer 34

minor arterial circle of the iris

Question 35

the 2 types of pigment cells found in the stroma layer of the iris

Answer 35

melanocytes (most cells) and clump cells (spherical, without processes, darker, most frequent in pupillary region)

Question 36

origin and path of the 2 anastomoses of the stroma layer of the iris

Answer 36

originate at the anterior ciliary arteries an long posterior ciliary arteries and run in a radial direction towards pupillary margin

Question 37

what kind of muscle is the posterior membrane (anterior epithelium)?

Answer 37

non-striated, smooth muscle

Question 38

cells found in the posterior membrane (anterior epithelium) layer of the iris ?

Answer 38

myoepithelial cells

Question 39

apex and base of the myoepithelium cells contains

Answer 39

apex: forms the epithelium, faces posteriorly base: forms the smooth muscle fibers, faces anteriorly

Question 40

what is the extent of the dilator muscle?

Answer 40

extends from root of iris to mid sphincter

Question 41

what are the 3 groups of spurs on the dilator

Answer 41

1. Grunnert's 2. Von Michel's 3. Fuchs

Question 42

location of Grunnert's spurs on the dilator

Answer 42

most peripheral, at root of iris

Question 43

location of Von Michel's spurs on the dilator

Answer 43

peripheral edge of sphincter

Question 44

location of Fuchs spurs on the dilator

Answer 44

midpoint of sphincter

Question 45

what innervates the dilator muscle?

Answer 45

sympathetic NS | pupils dilate in 'flight of flight' response

Question 46

the posterior pigment epithelium layer of the iris is an extension of the

Answer 46

anterior non-pigment epithelium

Question 47

in which direction does the apex and base face for cells in the posterior pigmented epithelium of the iris?

Answer 47

apex faces anteriorly | base faces posteriorly (basement membrane)