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Ocular Anatomy > Lecture 9: 12/14 > Flashcards

Lecture 9: 12/14 Flashcards

1
Q

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

A
  1. central pupillary zone

2. peripheral ciliary zone

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2
Q

junction between the 2 zones of the iris is called

A

the collarette

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3
Q

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

A

0.6mm thick

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4
Q

appearance and location of the collarette

A

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

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5
Q

explain the pupillary ruff

A

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

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6
Q

the three areas of the ciliary zone

A
  • an inner area adjacent to the collarette
  • a furrowed central area
  • a marginal cribiform area next to the ciliary body
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7
Q

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

A

Fuch’s crypts

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8
Q

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

A

adjacent to the collarette and result of the erosion

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9
Q

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

A

ginioscopy

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10
Q

what are two things unique about the marginal cribriform area?

A
  • small little crypts called ciliary crypts

- iris pectinate fibers seen in this area

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11
Q

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

A

there are contraction furrows that run concentric with the pupil

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12
Q

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

A

smooth, slight radial ridges

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13
Q

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

A
  1. contraction folds of Schwalbe
  2. circular folds
  3. structural folds of Schwalbe
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14
Q

the contraction folds of Schwalbe are:

A

grooves that run from the pupillary margin peripherally to the collarette

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15
Q

circular folds are:

A

concentric around the pupil

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16
Q

radial folds (most peripheral) run

A

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

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17
Q

4 layers of the iris, from anterior to posterior

A
  1. anterior limiting layer
  2. stroma
  3. posterior membrane (anterior epithelium)
  4. posterior pigmented epithelium
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18
Q

what 2 iris layers were derived from mesoderm?

A
  • anterior limiting layer

- stroma

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19
Q

what 2 iris layers were derived from neuro-ectoderm?

A
  • posterior membrane (anterior epithelium)

- posterior pigmented epithelium

20
Q

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

A

anterior limiting layer

21
Q

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

A

anterior limiting layer

22
Q

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

A
  • fibroblasts

- melanocytes

23
Q

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

A

from the most anterior layer, located root to margin

24
Q

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

A

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

25
Q

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

A

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

26
Q

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

A

stroma

27
Q

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

A

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

28
Q

sphincter muscle width (cross section) is _____ mm

A

0.75 mm

29
Q

location and action of the sphincter muscle

A

it is a flat muscle that runs radially around the pupil

-when it contracts, it makes the pupil smaller

30
Q

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

A

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

31
Q

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

A

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

32
Q

blood vessels of the iris reside in the ______

A

stroma

33
Q

blood vessels enter the iris from the :

A

major arterial circle of iris

34
Q

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

A

minor arterial circle of the iris

35
Q

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

A

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

36
Q

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

A

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

37
Q

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

A

non-striated, smooth muscle

38
Q

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

A

myoepithelial cells

39
Q

apex and base of the myoepithelium cells contains

A

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

40
Q

what is the extent of the dilator muscle?

A

extends from root of iris to mid sphincter

41
Q

what are the 3 groups of spurs on the dilator

A
  1. Grunnert’s
  2. Von Michel’s
  3. Fuchs
42
Q

location of Grunnert’s spurs on the dilator

A

most peripheral, at root of iris

43
Q

location of Von Michel’s spurs on the dilator

A

peripheral edge of sphincter

44
Q

location of Fuchs spurs on the dilator

A

midpoint of sphincter

45
Q

what innervates the dilator muscle?

A

sympathetic NS

pupils dilate in ‘flight of flight’ response

46
Q

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

A

anterior non-pigment epithelium

47
Q

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

A

apex faces anteriorly

base faces posteriorly (basement membrane)

Ocular Anatomy (20 decks)

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