Ciliary Body, Choroid, & Vitreous

base and apex of CB

base anteriorly at the scleral spur, iris root, and AC

apex pointing posteriorly towards the ora serrata

what is anterior and posterior to the CB

anterior: sclera

posterior: posterior chamber and vitreous

2 main functions of CB

1. aqueous humor production

2. accommodation

what part of the CB produces AH

non-pigmented ciliary epithelial cells

where is AH secreted

posterior chamber

ciliary body innervation

innervated by the parasympathetic fibers in the SPCNs from the ciliary ganglion

what happens when the ciliary muscle receives parasympathetic innervation and where is the innervation coming from

coming from parasympathetic fibers in the SPCNs from the ciliary ganglion

causes ciliary fibers to contract, making the lens more spherical, and causing the eye to accommodate

pars plicata

aka corona ciliaris

wide anterior part of CB that has 70-80 ciliary processes that extend into the posterior chamber

ciliary processes

radial folds in the pars plicata

valleys of kuhnt

heavily pigmented areas between ciliary processes in pars plicata where zonular fibers of the lens attach

does AH get produced in the pars plana or pars plicata

non-pigmented ciliary epithelium of the pars plicata

aqueous humor flow

pars plicata > posterior chamber > through pupil > anterior chamber > TM

pars plana

aka orbicularis ciliaris

flatter more posterior portion of the CB

borders of pars plana

anterior: pars plicata

posterior: ora serrata

_________ serves as the anterior border to the retina

pars plana

dentate processes

parts of the peripheral retina (ora serrata) that extend onto the pars plana

oral bays

posterior extensions of pars plana that lie between dentate processes

enclosed oral bay

when neighboring dentate processes join together

ruptured or damaged zonules cause _________ or _____________ of the lens

subluxation or dislocation

layers of the CB (outer to inner)

supraciliaris > ciliary muscle > ciliary stroma > pigmented ciliary epithelium > non pigmented ciliary epithelium

what is the supraciliaris attached to

loosely attached to underlying sclera but not the scleral spur

outermost layer of ciliary body

supraciliaris

composition of supraciliaris

loose CT with many collagen bonds

what is the supraciliaris continuous with and where

suprachoroid

at the ora serrata

what travels through the supraciliaris

blood vessels and nerves to reach the anterior part of the eye

what causes a ciliary body detachment

fluid build up in the supraciliaris

largest intrinsic muscle of the eye

ciliary musclewh

what kind of muscle is the ciliary muscle

smooth muscle

which layer of the CB is responsible for accommodation

ciliary muscle

innervation of the ciliary muscle

mostly parasympathetic CN III fibers

some sympathetic fibers

what anchors the ciliary muscle

anteriorly: scleral spur

posteriorly: stroma of the choroid

3 types of ciliary muscle fibers

1. longitudinal muscle fibers (of brucke)

2. radial fibers

3. Muller’s annular muscle

what muscle fibers make up the largest % of ciliary muscle fibers

longitudinal muscle fibers

what are the outermost ciliary muscle fibers

longitudinal muscle fibers

shape of longitudinal muscle fibers

long v-shaped fibers that stretch across the CM

originate at the scleral spur and TM

muscle stars

parts of the longitudinal muscle that extend into the choroid into star shaped terminations

shape, origin, and termination of radial fibers

extend in a V-shape from the scleral spur

terminate in connective tissue near the base of the ciliary processes (pars plicata)

what muscle makes up the smallest portion of the CM

Muller’s annular muscle

most medial/innermost muscle of CM

Muller’s annular muscle

shape and origin of Muller’s annular muscle

circular muscle bundles that originate at the scleral spur

which CM muscle is near the major arterial circle of the iris

Muller’s annular muscle

what structure is Muller’s annular muscle next to

major arterial circle of the iris

what structure is in the ciliary stroma

major circle of the iris

what layers is the ciliary stroma between

ciliary muscle and ciliary epithelial layers

vascularization of ciliary stroma

highly vascularized

contains major circle of iris

location of major arterial circle of iris

inward from the CM in the ciliary stroma near the iris root

has large fenestrated capillaries near ciliary epithelium of pars plicata

arteries that form the major arterial circle of iris

ACAs and LPCAs

what stops large molecules from getting into the anterior chamber from the fenestrated major circle of iris

large molecules are able to get through the fenestrated capillaries in the major circle of the iris

NPCE of the pars plicata contains tight zonular junctions that blocks these large molecules from entering the anterior chamber

protein concentration of the aqueous vs. blood and why

protein concentration is much lower in aqueous than blood

7% in blood, 2% in aqueous

tight junctions of non-pigmented ciliary epithelium of the CB stop protein molecules that leak out of the major circle of the iris from entering the aqueous in the anterior chamber

what is aqueous humor made from

plasma that escapes the blood stream from the fenestrated capillaries of the major arterial circle of the iris

how are the 2 layers of ciliary epithelium arranged

2 layers of epithelium line the CB joined apex to apex via zonula occludens

histology of pigmented ciliary epithelium

outer cuboidal epithelial layer attached to ciliary stroma via basal lamina of the its BM (apex faces NPCE)

what is the pigmented ciliary epithelium continuous with anteriorly and posteriorly

anteriorly: anterior pigmented iris epithelium and its BM

posteriorly: RPE and inner BM of Bruch’s membrane (outer retina)

histology of NPCE

inner cuboidal epithelial layer that lines the posterior chamber

2 areas lens zonules arise from

1. valleys of Kuhnt of pars plicata

2. NPCE basal lamina of pars plana

NPCE contains organelles that are necessary for ____________

aqueous secretion

what is the NPCE continuous with anteriorly and posteriorly

anteriorly: pigmented posterior epithelium of iris epithelium and its basal lamina

posteriorly: ora serrata and neural retina, basal lamina continuous with ILM of retina (inner retina)

CB blood supply

LPCAs and major arterial circle of iris

venous drainage of CB

ciliary veins drain through vortex veins

what does the parasympathetic system innervate in the CB

innervates the ciliary muscle for accommodation

what does the sympathetic system innervate in the CB

innervates arteries within the CB

where does the CB get parasympathetic innervation from

CN III parasympathetic fibers travel with SPCNs from the ciliary ganglion

where does the CB get sympathetic innervation from

sympathetic nerve fibers from the superior cervical ganglion of the sympathetic ganglion chain travel with SPCNs and LPCNs

where does the CB get sensory innervation from

sensory nerve fibers from the trigeminal ganglion of CN V1 travel with LPCNs

ganglions of sympathetic, parasympathetic, and sensory innervation of the CB

sympathetic: fibers come from the superior cervical ganglion

parasympathetic: fibers come from the ciliary ganglion

sensory: fibers come from the trigeminal ganglion of V1

what nerves do sympathetic, parasympathetic, and sensory fibers travel to the CB with

sympathetic: LPCNs and SPCNs

parasympathetic: CN III fibers travel with SPCNs

sensory: CN V1 fibers travel with LPCNs

what is the choroid positioned between

sclera and RPE of the retina (outer retina)

anterior and posterior borders of the choroid

anterior: ora serrata (where CB ends)

posterior: optic nerve

where is choroid the thickest

posterior pole (0.2 mm)

where is choroid the thinnest

ora serrata (0.1 mm)

composition of choroid

2 central vascularized layers surrounded by 2 non-vascularized membranes (4 layers total)

layers of the choroid (outer to inner)

suprachoroid lamina (next to sclera) > choroidal stroma > choriocapillaris > bruch’s membrane (next to RPE)

suprachoroid lamina

aka lamina fusca

potential space between sclera and choroidal vessels

supra choroid means above the choroid

contents of suprachoroid lamina

loosely packed with collagen fibers, fibroblasts, melanocytes, and ECM

what passes through suprachoroid lamina

LPCAs and LPCNs

where do LPCNs extend from

mid-equatorial region to ora serrata and 3 & 9 o’clock

what layer of the choroid belongs to the choroid and sclera

suprachoroid lamina

if it was split, part of it would attach to sclera and part of it would attach to choroid

choroidal stroma

loose CT layer that contains choroidal BVs, nerves, and dense melanin granules

what innervates choroidal BVs and what does it cause

sympathetic NS

causes vasoconstriction

what is the most common primary intraocular tumor in adults

choroidal melanoma

why are melanomas of the eye most common in the choroid, and what layer causes this

choroidal stroma

has extremely high density of blood vessels and melanin granules

__________ vessels in the choroidal stroma form 2 separate layers

SPCA

what 2 layers are formed by SPCAs in the stroma

Haller’s and Sattler’s layer

Haller’s layer is more (posterior/anterior) with (larger/smaller) vessels

Haller’s layer is more posterior with larger vessels

closer to sclera and suprachoroid lamina

Sattler’s layer is more (posterior/anterior) with (larger/smaller) vessels

Sattler’s layer is more anterior with smaller vessels

Haller’s layer vessels branch to form ________________

Sattler’s layer vessels branch to form __________________

Haller’s vessels branch to form smaller vessels of Sattler’s layer

Sattler’s vessels branch to form capillary beds

what drains blood from the capillary beds of Sattler’s layer

large vortex veins

tributaries of vortex veins located in Haller’su

unlike most veins, vortex veins do not contain ____________

valves

what kind of capillaries are found in the choriocapillaris and where are they most concentrated

fenestrated capillaries

most concentrated in the macula

role of choriocapillaris

supplies blood to outer retina

what cells regulate blood flow in the choriocapillaris

pericytes

where can pericytes be found and what do they do

surround capillaries of choriocapillaris

regulate blood flow

what disease can damage pericytes

diabetes mellitus

what impact does diabetes mellitus have on the choroid, and how does this cause diabetic retinopathy

diabetes damages blood vessels and pericytes of the choroid

prevents proper blood flow and regulation of blood flow, preventing nutrients and oxygen from getting to the macula, resulting in DR

innermost layer of the choroid

Bruch’s membrane

basal lamina of the choroid

Bruch’s membrane

bruch’s membrane

fusion of choriocapillaris and RPE basement membrane composed of 5 layers

5 layers of Bruch’s membrane

BM of choriocapillaris, outer collagenous layer, elastic layer, inner collagenous layer, BM of RPE

function of Bruch’s membrane

allows passage of waste and nutrients between choriocapillaris and RPE

nutrients pass from ________ through Bruch’s to __________

from choriocapillaris

to retina