Uvea Flashcards
What is the uvea?
Middle layer of the globe
What does the uvea consist of?
Iris
Ciliary body
Choroid
What forms the anterior uvea?
Iris and ciliary body
What forms the posterior uvea
Choroid
Is the uvea vascularise? is it pigmented?
Yes
Yes
What is the most rostral part of the uvea? Describe it
Iris
Forms ring around pupil
Sphincter that can dilate and constrict
What shape pupils do dogs and pigs have? What about cats?
Circular
Cats oval when dilated, vertical when constricted
Ungulates have pigmented masses on their pupillary margin of the iris. What are they called? What are they for?
Corpora nigra - pigemented extensions of the iris
Improve mitosis
The iris is separated into the 2 zones. What are these zones and what separates them?
Pupillary zone
Ciliary zone
Separated by the colarette
What does the pupillary zone of the iris contain?
Incomplete arterial circle
From posterior ciliary arteries
What innervates the constrictor muscle? What does this muscle do?
Parasympathetic innervation (oculomotor CN III) Determines pupil shape
What innervates the dilator muscle?
Sympathetic innervation
What is different about the dilator muscle in non-mammals?
Non-striated musce
What lines the posterior iris?
Pigmented epithelium
extended in ungulates to form corpora nigra
Where is the ciliary body located in relation to the iris?
Posterior
What does the ciliary body consist of? What does it form part of?
Ciliary process
Ciliary body muscles
Forms part of idiocorneal angle
What is the function of the ciliary body?
Produces aqueous humour
Helps its drainage
Anchors the zonular fibres that suspend the lens
The main portion of the ciliary body is what type of muscle in mammals? What about non-mammals?
Smooth muscle in mammals
Striated in non-mammals
What 2 layers of epithelium cover the ciliary body?
Inner non-pigmented epithelium
Outer pigmented epithelium
What is the function of the non-pigmented epithelium of the ciliary body?
Forms blood/aqueous barrier
Via tight junctions between cells
What happens in diseases where there is alteration to the non-pigmented epithelium of the ciliary body?
Disrupts blood/aqueous barrier
Allows proteins and cells into the humour
What are the 2 parts to the ciliary body?
Pars plicata
Pars plana
What does the pars plicata have and why?
Ciliary processes - increase SA for aqueous production
What is different about the pars plicata in reptiles/birds?
It’s attached to the lens
What suspends the lens in mammals?
Zonular fibres from the ciliary process
What is the idiocorneal angle?
Most anterior part of ciliary body
Where root of iris, anterior ciliary body and cornoscleral junction meet
What is the function of the idiocorneal angle?
Main site of aqueous humour drainage
Where is aqueous humour produced? How does it get to the idiocorneal angle to drain?
Posterior chamber
Through the pupil
What ligaments does the idiocorneal angle contain?
Pectinate ligaments
What is the choroid layer of the uvea between?
Sclera and retina
Describe the choroid of the uvea
Highly vascular
Pigmented
Between sclera and retina
What are the 4 layers of the choroid?
Suprachoroidae
Large vessel layer
Medium vessel layer
Choriocapillaris
What is the tapetum lucid? What is its function? Where is it located?
Fibrous, light reflecting structure - allows to see in dark but with less acuity
Found within medium vessel layer of choroid
Which layer of the choroid contains capillaries that supply the retina?
Choriocapillaris
What is the function of the large vessel layer of the choroid?
Cool the eye
Heat via light
