Ciliary Body (Lecture 5)

What are the general characteristics & gross morphology of the ciliary body?

1. Anterior continuation of choroid

2. Triangular in shape

3. Longer temporally

4. Darker than choroid

5. Very vascular ocular tissue

6. Band or ring of smooth muscle tissue

What is the shape of the ciliary body?

Triangular

Where is the ciliary body longest?

Temporally

Is the ciliary body darker or lighter than the choroid?

Darker

What describes the ciliary body's tissue?

Vascularized

What type of tissue does the ciliary body have?

Band or ring of smooth muscle

Where do we see the ciliary body always longest?

Inferotemporally- the most expanded quadrant of the eye

What are the dimensions of the ciliary body temporally?

7 mm

What are the dimensions of the ciliary body nasally?

6 mm

What are the functions of the ciliary body?

1. Aqueous production & outflow

2. Accommodation

3. Vitreous production

4. Blood-aqueous barrier

5. Production & attachment of zonules

What type of fluid does the ciliary body produce?

Aqueous & vitreous

What kind of barrier is present within the ciliary body?

Blood-aqueous

What structure does the ciliary body produce & attach?

Zonules

What does the ciliary body allow to do?

Accommodate

What structure is the ciliary body internal to?

Sclera

What structure is the ciliary body anterior to?

Choroid

What structure is the ciliary body posterior to?

Iris

What is ciliary muscle attached to?

Sclera

What attaches ciliary muscle to the sclera?

Scleral spur

What structure is the ciliary body adjacent to?

Posterior chamber

What does the ciliary body attach to via zonules?

Lens

What are the two gross anatomical subdivisions of the ciliary body?

1. Pars plicata

2. Pars plana

How much of the pars plicata accounts for the ciliary body?

1/3

What part of the ciliary body is the pars plicata located?

Anterior

What is the pars plicata closest to?

Lens

What does the pars plicata produce?

Aqueous

What does the inner surface of the pars plicata contain?

- Folds

- Ciliary processes

How much of the pars plana accounts for the ciliary body?

2/3

What part of the ciliary body is the pars plana located?

Posterior

What describes the inner surface of the pars plana?

Flat

What is the pars plana next to?

Retina

How much of the ciliary processes accounts for the ciliary body?

1/3

What part of the ciliary body is the ciliary processes located?

Anterior

How many ciliary processes does the pars plicata have?

70-80

What is the inner surface of ciliary processes thrown into?

Folds

What is the purpose of the surface area of the ciliary process?

Aqueous production

What are minor ciliary processes?

Plicae circulares

What are minor ciliary processes imporant for?

Attachment of zonules

Where are the minor ciliary processes located?

Along the sides (not peaks) of processes

Where is the pars plana of the ciliary body located?

Posterior 2/3

How wide is the pars plana?

3.5 - 4 mm

What describes the surface of the pars plana?

Flat inner surface

What describes the anterior area of the pars plana?

Thicker

What is the pars plana the transition between?

Retina & Ciliary body

What does the pars plana produce?

Components of vitreous

What is seen along the flat inner surface of pars plana?

Zonules

What is the pars plana adjacent to?

Retina

What does the pars plana contain that extend into the retina?

Oral bays

What are oral bays?

Excavations of the cilary body that extend into the retina

What are known as the "teeth" of retina that extend into the ciliary body?

Dentate processes

What are the 4 histological layers of the ciliary body?

1. Supraciliaris

2. Ciliary muscle

3. Stroma

4. Ciliary Epithelium

What does the supraciliaris contain?

Supraciliary space- Potential space that is continuous with suprachoroidal space

What describes the composition of the supraciliaris?

Fine collagen fibrils connect to sclera

What is the function of the supraciliaris?

Conduit for nerves & blood vessels

What is ciliary muscle similar to?

Smooth muscle elsewhere in the body

What are the fibers of the ciliary muscle covered by?

Basement membrane

What does the connective tissue between each of the ciliary muscle fibers contain?

- Nerves

- Collagen fibers

- Melanocytes

- Ground substance

- Nonfenestrated blood vessels

What shape does the ciliary muscle fibers give the ciliary body?

Triangular shape

What describes the ciliary body subdivisions?

1. Longitudinal

2. Radial

3. Circular

What describes the longitudinal part of the ciliary body subdivision?

Fibers that travel the longest direction & are the outermost fibers

What describes the radial part of the ciliary body subdivision?

Fibers run in a radial direction & are the middle fibers

What describes the Circular part of the ciliary body subdivision?

Fibers run circumferentially & are the inner most fibers

Where do all ciliary muscle fibers originate from?

Scleral spur

What does the contraction of ciliary muscle do to the scleral spur?

Moves the spur & enhances aqueous outflow

What does the contraction of ciliary muscle cause?

Changes shape of lens- accommodation

What sub division of muscle fibers of the ciliary muscle are clinically most important?

Longitudinal

Why are the longitudinal muscle fibers most clinically important?

Insert as muscle stars into the choroid

What can strong contraction of the ciliary muscle sometimes cause?

Retinal detachment

What describes the composition of the ciliary body stroma?

Thin layer of loose connective tissue

What does the connective tissue of the ciliary body stroma contain?

- Nerves

- Blood vessels

- Fibroblasts

- Lymph

- Mast cells

What describes the capillaries within the ciliary body stroma?

Fenestrated on all sides

What do the fenestrated capillaries of the ciliary body stroma provide?

Substances necessary for aqueous production

Where are the fenestrated capillaries found?

- Between the ciliary muscle & double epithelial layer

- Extends into the ciliary processes

What are the function of the desmosomes & zonula adherens between the epithelia of the ciliary body?

Prevent separation of the epithelial layers during ciliary body contraction

What is the ultrastructure & function of the blood aqueous barrier in the non-pigmented epithelium of the ciliary body?

Zonula occludens

The iris myoepithelium can be traced posteriorly to be continuous with what layer of the ciliary body?

Pigmented epithelium

The posterior pigmented epithelium of the iris can be traced posteriorly to be continuous with what layer of the ciliary body?

Non-pigmented epithelium

What is the origin of the zonules?

From non-pigmented epithelium

Where does the zonules mainly come off of?

Pars plana region & some from the valleys of the ciliary processes nonpigmented epithelium

What are zonules comprised of?

Mostly of fibrillin

What does the contraction of all three muscle fiber groups cause?

Accommodation- Fibers to work together

What do the ciliary muscles pull on to create accommodation?

Anterior choroid forward

What does the apex of ciliary processes pull on to create accommodation?

lens equator

What is the primary function of the movement of ciliary muscles/processes?

Relaxing of zonular tensions to allow accommodation to occur

What describes the blood supply to the ciliary body & ciliary processes?

Long posterior ciliary artery & major perforating branch of anterior ciliary anastomose to form the major arterial circle

What do branches of major arterial circle supply?

Ciliary body

What is the venous drainage of the ciliary body?

Anterior ciliary vein drains to vortex veins which drain to superior or inferior ophthalmic veins

Describe the parasympathetic innervation to the ciliary muscle:

1. Preganglionic cell bodies EW nucleus III

2. Travels with CN III

3. Synapse in ciliary ganglion (post ganglionic cell bodies)

4. Travels to short ciliary nerves

5. Causes parasympathetic activation of the M3 muscarinic receptor causes ciliary muscle contraction

6. Accommodation occurs

The activation of what causes the ciliary muscle contraction?

Activation of the M3 muscarinic receptor

Describe the sympathetic innervation to the ciliary body:

1. Superior cervical ganglion (synapse)

2. Post ganglionic cell bodies

3. Travels with ICA

4. Travels with ophthalmic nerve

5. Travels vai short and/or long ciliary nerves to relax ciliary muscle sympathetic Beta2-adregeneric receptors

6. Innervation relaxes the ciliary muscle

The innervation of what relaxes the ciliary muscle?

Sympathetic Beta2-adrengeric receptors

Describe the sensory innervation from the ciliary body to the iris:

1. Iris/ciliary body via V1 to long & short ciliary nerves

2. Travel to nasociliary nerve

3. Travel to ophthalmic nerve

4. Travel to trigeminal ganglion

5. Resulting in PAIN