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Ocular Biology > Ciliary body anatomy > Flashcards

Ciliary body anatomy Flashcards

1
Q

Ciliary body

A

anterior continuation of choroid

triangular in shape

longer temporaly

darker than choroid

most vascular tissue of eye

band of ring of smooth muscle tissue

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2
Q

ciliary body dimensions

A

always longest inferotemporally, most expanded quadrant of eye

temporally 5.6 - 6.3

nasallt 4.6 - 5.2

surgical dimensions are external corneoscleral limbus to end of ciliary body of ora serrata - 6mm nasally and 7 mm temporally

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3
Q

ciliary body functions

A

aqueous production and outflow

accommodation

vitreous production

blood-aqueous barrier

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4
Q

ciliary body location and relationship to structures

A

internal to sclera and attached scleral spur

anterior to choroid

posterior to iris

face of ciliary body bathed in aqueous in anterior chamber

lens attached to ciliary body via zonules

pars plicata and pars plana bathed by aqueous in posterior chamber

non pigmented epithelium is continuous with sensory retina posterior

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5
Q

anatomical subdivisions of ciliary body

A

1) Pars Plana

2) Pars Plicata

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6
Q

pars plana

A

posterior 2/3 of ciliary body

3.5 - fmm wide

flat inner surface

thicker anteriorly

adjacent to ora serrata and retinal

produces components of vitreous

has zonules matted down along inner surface
oral bays

dentate processes

attached to vitreous base - extends 2 mm over posterior pars plana

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7
Q

striae ciliaris

A

component of pars plana

  • strips extending from dentate processes
  • run along inner surface
  • gvies par plana a striated appearance
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8
Q

meridional folds

A

meridonal folds begin in ora serrata and runs posteriorly and perpendicularly to it in a meridional fashion

radially aligned elevation of peripheral retina

aligned with dentate processes

associated with retinal breaks

meridional complex -> super meridional fold

fundamental and consistent feature of meridional complex is atypical dentate process aligns with a ciliary process

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9
Q

pars plicata

A

anterior 1/3 of ciliary body

ciliary processes (70-80): inner surface is thrown into folds
-surface area for aqueous production

plicae circulares : smaller subsidiary folds

attachment of zonules

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10
Q

layers of ciliary body

A

supraciliaris

ciliary muscle

stroma

ciliary epithelium

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11
Q

supraciliaris

A

supraciliary space: potential space - continuous with suprachoroidal space

conduit for nerves and blood vessels

fine collagen fibrils connect to sclera

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12
Q

ciliary muscle

A

similar to smooth muscle elsewhere in body

fibers covered by basement membrane

connective tissue between fibers contains: nerves, collagen fibers, melanocytes, ground substance, nonfenestrated BV

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13
Q

longitudinal or meridional ciliary muscle fibers

A

outer most layer

origin- scleral spur and part of TM

V shaped fibers - base of V towards choroid

insertion - choroid and sclera to the equator

muscle stars - choroid

pilocarpine can cause retinal detachment

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14
Q

oblique or radial ciliary muscle fibers

A

intermediate muscle mass

origin - scleral spur

insertion - connective tissue of folds of pars plicata

v shaped fibers

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15
Q

circular ciliary muscle fibers

A

deepest muscle

annular muscle

v shaped fibers - top of V (very wide) origin from scleral spur and anchor into ciliary stroma

run circumferentially forming a sphincter

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16
Q

ciliary muscle innervation

A

parasympathetic M3 muscarinic receptors - innervation activates muscle contraction

sympathetic Beta2 -adrenergic receptors - innervation relaxes ciliary muscle

17
Q

ciliary muscle action

A

contraction of all 3 muscle fiber groups causes fiber groups work together

ciliary muscle pulls anterior choroid forward

apex of ciliary processes pulls towards lens equator

primary fxn of releasing resting zonular tension to allow accommodation to occur

18
Q

stroma (inner connective tissue layer)

A

separates epithelium from ciliary muscle

  • thickest in pars plicata
  • anteriorly joins connective tissue of iris
  • posteriorly joins: stroma of choroid, collagenous and elastic layer of Bruch’s
  • passage for blood vessels and nerves
    contents: cells - fibroblasts, melanocytes, lymph, mast cells, loose collagen, fenestrated blood vessels
19
Q

ciliary epithelium

A

double epithelial layer

cells oriented apex to apex

pigmented epithelium

non-pigmented epithelium

20
Q

pigmented epithelium (ciliary epithelium)

A

outer layer (closer to stroma)

anterior continuation of RPE

base toward ciliary stroma

heavily pigmented-melanin in apex of cell

BM continuous with Bruch’s

gap jxn - communication b/n PE and NPE and b/n adjacent PE cells

desmosomes, macula adherens - firm attachment b/n PE and NPE and b/n adjacent PE cells

21
Q

Non Pigmented epithelium (ciliary epithelium)

A

inner layer of epitheilum

anterior continuation of sensory retina

shape: tall columnar in pars plana, low cuboidal in pars plicata
fxn: blood aqueous barrier (zonula occludens), vitreous production (pars plana), aqueous production (pars plicata)

covered by basement membrane

22
Q

blood aqueous barrier

A

ultrastructure and location: zonula occludens at level of NPE

fxn: prevent substances from flowing from fenestrated blood vessels of ciliary body stroma into the aqueous

23
Q

NPE in pars plicata

A

tips or crests of NPE are site of active secretion, hence numerous mitochondria, rough ER, pinocytic vesicles, Na-K activated ATPase and carbonic anhydrase

24
Q

NPE relationship with PE

A

gap jxn: communication b/n PE and NPE and b/n adjacent PE cells

desmosomes, macular adherens: firm attachment b/n PE and NPE and b/n adjacent PE cells
-firm attachment to prevent separation during contraction of ciliary uscle

25
Q

NPE of ciliary body

A

NPE has basal infoldings

pars plicata

secretory fxn

26
Q

Zonules

A

composition produced by NPE

origin:
pars plana: 1.5 mm from ora
-stay flat, matted down
pars plica: arise form valleys

fxn:

accommodation

27
Q

accommodation

A

ciliary muscle is richly innervated with large numbers of cholinergic nerve terminals

contraction causes strong anterior and inward movement of ciliary processes

result is well coordinated anterior-inward squeezing effect, relaxing tension on zonules

28
Q

ciliary body blood supply

A

major circle of iris

  • long posterior ciliary artery
  • major perforating branch of anterior ciliary

branches of major circle

29
Q

ciliary process blood supply

A

each ciliary process served by set of anterior and posterior arterioles

anterior arteriole supply

  • larger capillaries: aqueous production
  • posterior arteriole: smaller capillaries
  • blood flow is from anterior to posterior
  • supply is from major arterial circle (MAC)

allows high volumes of blood into and out of ciliary process to lead aqueous production

30
Q

venous drainage

A

vortex veins or anterior ciliary veins

31
Q

ciliary body innervation - parasympathetic

A

parasympathetic:

  • originate in EW nucleus
  • travel with CN 3 (oculumotor nerve)
  • synapse in ciliary ganglion
  • postsynaptic fibers from ciliary ganglion from short ciliary nerves
  • parasympathetic activation of M3 muscarinic receptors causes ciliary muscle contraction : accommodation
32
Q

ciliary body innervation - sympathetic

A

superior cervical ganglion to ciliary muscle, epithelium and blood vessels

sympathetic beter2-adrenergic receptors - innervation relaxes ciliary muscle
-ciliary body is also known to receive sympathetic innervation via long ciliary nerves

NPE and alpha 2, beta 1, beta 2 receptors - used in glucoma medication management

33
Q

ciliary body innervation - sensory

A

sensory - afferent pathways

  • sensory fibers of long ciliary nerves in ciliary body -> nasociliary nerve -> V1 (ophthhalmic) -> CNS
  • sensory fibers of short ciliary nerves in CB -> thru short ciliary gang (no synapse) -> V1 (ophthalmic) -> CNS

Ocular Biology (9 decks)

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