Ocular: Uvea (Ciliary Body) Flashcards
What are the functions of the ciliary body?
-produce and secrete aqueous humor
-influence aqueous outflow
-accommodation
Where is aqueous humor produced?
Ciliary stroma (MACI) -> ciliary processes -> posterior chamber
How is ciliary body involved with accommodation?
The ciliary muscle controls the zonular tension (lens shape)
2 main portions of cilairy body:
-anterior pars plicata
-posterior pars plana
Pars plicata:
-contain ~ 75 ciliary processes 360 degrees around lens
Pars plana extend posteriorly to the __________
Ora serrata
Both pars plana and plicata contain:
-2 layers of inner epithelium
-3 layers of smooth muscle
-outer supraciliaris
The ciliary body is ________ oriented
Circularly
What is the supraciliaris?
Outermost layer of ciliary body between sclera and ciliary body
What allows the ciliary body to slide against sclera?
Loose connective tissue in the supraciliaris
What is the supraciliary space continuous with?
-continuous with the suprachoroidal space
What happens/what is located in supraciliary space?
-uveoscleral pathway of aqueous outflow
-ciliary nerves
Where is ciliary body detachment most common?
Histological preparations, not often in vivo
Ciliary smooth muscles (external to internal):
-longitudinal muscle
-radial muscle
-circular muscle
What does the longitudinal muscle parallel with?
Sclera
What is the Origin and insertion of the longitudinal muscle?
O: scleral spur
I: anterior choroid
What happens when longitudinal muscle contracts?
Pulls the scleral spur posterior leading to the opening of the TM pores which increases aqueous outflow
Longitudinal muscle bundles run in a ___ shape
V shape
What is located at the base of the V in the longitudinal muscle bundle?
Scleral spur
What is the location of the apex of the V in the longitudinal muscle bundle?
Epichoroidal star in pars plana region
What shape is seen in the radial muscle bundles?
Shorter, wider, overlapping V’s
What is at the base of the V in the radial muscle bundles?
Scleral spur -> origin
What is at the apex of the V in the radial muscle bundles?
Connective tissue near the base of the ciliary processes —> insertion
What is seen in the circular (annular) muscle?
360 degree sphincter around the inside of the ciliary body
What happens when circular muscle contracts?
Circumferential space decreases between the ciliary processes and lens
What does contraction of the circular muscle lead to in relation to accommodation?
Decrease in zonular tension
What lies between the processes of pars plicata?
Valleys on Kunht
Zonules originating forms he valleys on either side of the ciliary processes share a…
Common line of attachment on the lens
Pars plana have _________ that extend between ____________
Oral bays, dentate processes
Where do the zonules originating on the internal limiting membrane of the pars plana travel between?
Ciliary processes
Is the ora serata apart of the ciliary body?
NO
Where is the ora serata?
Beginning of retina and choroid anteriorly
Where does the ora serata insert?
Onto the pars plana via the dentate processes
What is a pars-plana vitrectomy?
Creation of portal to enter the eye 3.5-4mm posterior to the limbus in order to remove vitreous
What forms the core of each ciliary process?
Ciliary body stroma
Where is the ciliary body stroma located?
Between muscle and epithelium
Is the ciliary body stroma vascular?
Yes, there is MACI and large, fenestrated capillaries
What is Loose connective tissue in the ciliary body stroma continuous with?
The tissues between muscle and iris roots
What is the ciliary body epithelium?
Two layers of epithelium extending from pars plicata through pars plana
What is the outer ciliary body epithelium?
Pigmented ciliary epithelium located closer to stroma/muscle
What is inner ciliary body epithelium?
Non-pigmented ciliary epithelium lining the posterior chamber
What is NPCE specialized for?
Aqueous secretions into posterior chamber
What is more abundant in NPCE when compared to PCE?
Mitochondria and microvilli
There are ________ between the non-pigmented ciliary epithelium at the apical ends forming the __________________
Tight junctions, blood aqueous barrier
_____________ between PCE and NPCE pars plicata
Gap junctions
What do gap junctions between PCE and NPCE permit?
Movement of ions from plasma to facilitate aqueous formation in pars plicata
Where are desmosomes located in the ciliary body epithelium?
-between PCE and NPCE apically
What is the basement membrane lining the NPCE?
Internal limiting membrane os the ciliary body
Where is the attachment point of zonules in the pars plana region?
Internal limiting membrane of ciliary body
Where does the continuation of cell layers in the ciliary body epithelium stem from?
Development of the outer and inner layers of the embryonic optic cup
What is ciliary body epithelium continuous with anteriorly?
Anterior myoepithelial basement membrane of iris
What is ciliary body epithelium continuous with posteriorly?
Inner basement membrane of bruch’s membrane
Which two fibers are secreted by the NPCE during embryological development?
Elastin and fibrillin
What is the function of the anterior zonules?
-stabilize the lens
Where do anterior zonules (from pars plicata) originate?
Valleys of kuhnt on either side of ciliary process that have a common line of attachment
Where do posterior zonules (from pars plana) go? What do they do?
-extend through anterior vitreous inserting into valleys of kuhnt
-pull ciliary body back into its non-accommodative position
Steps of accommodation:
-contract ciliary body muscles
-space between inner portion of ciliary body and lens decreases
-zonules relax
-lens thickness increases
-lens power increases
What does the MACI supply?
Ciliary body processes and anterior ciliary musculature
Where does MACI get most of its blood?
Most from LCAs and rest from ACAs (12 and 6 o’clock)
What are the anterior arterioles off of MACI?
-Marginal capillaries at the tips of capillary processes
-are large and fenestrated
What do the anterior arterioles off MACI produce?
Filtrate for aqueous production
What are the posterior arterioles off of MACI?
-Interior portion of capillary processes
-tiny, non-fenestrated
What does the posterior arterioles off MACI supply?
Ciliary musculature
Anterior and posterior arterioles off MACI flow __________ to __________ and eventually drain into ___________
Anterior to posterior, vortex veins
MACI is primarily supplied by:
LPCA > ACA
Where does MACI supply blood?
Ciliary processes and anterior ciliary musculature
What is intramuscular circle supplied by?
ACAs > LPCAs
What does the IMC supply?
Posterior ciliary musculature
What is the function of the IMC aside from supplying posterior ciliary musculature?
Providing recurrent vessels posterior to help supply anterior choroid
Parasympathetic innervation of ciliary muscle:
-pregang fibers: EWN in midbrain -> synapse in ciliary ganglion
-postgang fibers: leave as SCN -> pierce sclera and travel in suprachoroidal space -> superciliary space -> ciliary muscle -> accommodation
Sympathetic innervation to ciliary muscle:
Superior cervical ganglion -> LPCN -> relaxes ciliary muscle
Which receptors increase aqueous humor formation? Where are they located?
Beta 1 and Beta 2, located in NPCE
Which receptor decreases aqueous humor production and where is it located?
Alpha receptors on the ciliary body blood vessels via vasoconstriction
Which receptor is involved with parasympathetic control? Where?
M3 receptor, in the smooth muscle to the ciliary body
Sensory pathway to ciliary body:
Trigeminal nerve -> V1 -> nasociliary nerve -> LPCN
What is seen in a plateau iris configuration?
The ciliary body is anteriorly displaced/rotated which causes the iris root to be parallel with the cornea/sclera (not good) —> narrow angle
*can be corrected with laser
Plateau iris syndrome:
Similar to plateau iris configuration but CANNOT be corrected with a laser
