L47 The Ciliary Body & Accommodation Flashcards
What are the parts of the Ciliary Body?
The Pars plana (flat and thin part) & the Pars Plicata (pleated bit) and ora serrata.
[lens isnt present in the diagram but would be hanging above the pars plicata somewhere]
[The ciliary body joins onto the retina in the regioncalled the ora serrata - retina has been chopped off the image]
In a Dissection of the human anterior eye from behind you should be able to identify the Pars Plicata, Pars Plana, and Ora Serrata.
Where the Pars Plana joins the retina is called the ora serrata.
Other labels can be seen on the diagram.
The central yellow circle is the lens and the black rim around it is the iris.
Why is the Ora Serrata called the Ora Serrata?
Serrata - coming from the Latin word that means serrated. (think saw edge).
It is because it has serrated edges made up of Dentate bays and Dentate processes.
Why are dentate processes important?
Because they are where suspensory ligaments attach to (which attach the ciliary body to the lens).
When we talk about the CILIARY processes (don’t get confused with the dentate processes) what are we talking about?
We are referring to the ‘pleated’ structure of the Plars Plicata.
These ciliary processes are actually 3D ‘fin-like’ structures.
How many layers of epithelium is the ciliary process covered by and what’s so special about them?
It is covered by two layers of epithelium - an inner unpigmented epithelium and outer pigmented (contains melanin) epithelium. (inner and outer refer to proximity to the inside of the eye- remember these are 3D ‘fin-like’ projections).
Does the Plars Plana have two epithelium?
Yes -It is covered by two layers of epithelium - an inner unpigmented epithelium and outer pigmented (contains melanin) epithelium.
What happens at the Ora Serrata?
The unpigmented epithelium of the Plars Plana stops and is replaced by the retina whereas, the outer pigmented epithelium of the ciliary body carries on and goes under the retina and now becomes the retinal pigment epithelia (RPE).
Most of the ciliary body is covered in a pigmented and unpigmented epithelial cell layer however, there is one exception- what is it?
The tips of the ciliary processes contain only unpigmneted epithelia making them appear white - the reason for which is unknown.
