The Eye Flashcards
What are the 3 layers of the eyeball?
- Fibrous coat
- Vascular coat
- Sensory coat
What are the components of the fibrous coat?
- Sclera
- Cornea
What are the components of the vascular coat?
- Iris
- Ciliary body
- Choroid
What structure means that the vascular coat is incomplete anteriorly?
Pupil
Which layer receives a rich blood supply?
Vascular coat
What is the main component of the sensory layer?
-Retina
What does the retina contain?
Light sensitive rods and cones
Where does the retina end anteriorly?
Serrated margin a little bit anterior to the equator known as the ora serrata
What is the cornea?
The anterior 1/6 of the fibrous layer which is transparent and is a window to allow light rays to enter the eyeball
What is the sclera?
The opaque posterior 5/6 of the fibrous coat which gives attachment to muscles moving the eyeball
Why is the cornea transparent?
Due to the very regularly arranges collagen fibres
What does the ciliary body do?
Suspends the lens and produces aqueous humor
What does the choroid do?
Supplies blood to the outer layers of the retina
What does the iris do?
Controls the diameter of the pupil and thereby control the amount of light rays entering the eyeball
How many histological layers does the retina have?
10
Zonules
Thin fibrous suspensory ligaments attaching the lens to the ciliary body
What does the iris contain?
Radial and concentric muscles to help control the diameter of the pupil
What is the crystalline lens?
A transparent, crystalline biconvex structure which is suspended by zonules from the ciliary body. It can change shape.
How is the lens attached to the ciliary body?
By zonules at 360 degrees
Anterior segment
Area in front of the crystalline lens
Posterior segment
Area behind the crystalline lens
What does the anterior segment contain?
Watery fluid called aqueous humor
What does the posterior segment contain?
Transparent gel called vitreous humor
What does the aqueous humor do?
Helps maintain intraocular pressure
What does the vitreous humor do
Help cushion the retina by pushing it back
What pressure is our eyeball maintained at?
21mmHg
What happens in trauma when the vitreous humor becomes liquefied?
Increases the chance of retinal detachment
Anterior chamber
Area of the anterior segment in front of the iris
Posterior chamber
Area of the anterior segment behind the iris
Describe the flow of aqueous humor.
- Produced by ciliary body
- Flows through posterior chamber
- Exits posterior chamber via pupil
- Drainage apparatus located at the angle of the anterior chamber
Where is the angle of the anterior chamber found?
Between the cornea, sclera and iris
What is the name of the drainage system of the aqueous humor?
Trabecular meshwork
After it enters the trabecular meshwork, what happens to the aqueous humor?
It drains into the Schlemm’s canal then into episclera veins sitting on the sclera
What structure can you see when you look through the aperture of the eyelids?
- Sclera
- Cornea (via reflection of light)
- Iris
- Pupil
