Visual System Flashcards
What forms the supraorbital margin?
Frontal bone (with supraorbital notch for the supraorbital nerve)

What forms the infraorbital margin?
- Zygomatic bone (laterally)
- Maxilla (medially)

What forms the roof of the orbit?
Frontal bone, lesser wing of sphenoid

What forms the floor of the orbit?
Maxilla, zygomatic, palatine

What forms the lateral wall of the orbit?
Zygomatic, lesser wing of sphenoid

What forms the medial wall of the orbit?
Maxilla, lacrimal bone, ethmoid, body of sphenoid

Where will blowout fractures to the orbit normally occur?
To the lacrimal bone or ethmoid bone, as they are extremely thin and fragile.

What proportion of the eyeball is sclera?
5/6th of the eyeball

What does the sclera do?
Maintains the shape of the globe, offering resistance to internal and external forces

What two characteristics make the sclera strong?
- Made of collagen
- Laid down in whirls

What does the sclera provide attachment for?
Extraocular eye muscles
What are the 3 layers to the eye?
- Sclera and cornea
- Vascular supply
- Neural part

What proportion of the eyeball is cornea?
1/6th

What is the principal refracting component of the eye?
Cornea

What makes the cornea optimum for vision?
Being avascular and transparent

Why is the cornea transparent?
Because the collagen fibrils are uniform in diameter, evenly spaced and run in bundles (lamellae) parallel to one another.

What does scleral opacity vary depending on?
- Composition of the stroma
- Hydration
- Size and distribution of collagen

What will happen to the order of collagen fibrils in the cornea if it is damaged?
The order will not necessarily return and can result in a scar

What is the anterior chamber of the eye?
Junction between iris and cornea

What happens at the anterior chamber of the eye?
Aqueous humour drains out of eye

What are the key structures of the anterior chamber of the eye?
- Cornea
- Trabecular meshwork
- Canal of Schlemm
- Aqueous humour drains into venous system via canal of Schlemm
- Ciliary body

What happens at the Canal of Schlemm?
Aqueous humour drains into the venous system

What forms the middle coat of the eye?
Uvea

What forms the middle layer of the eye?
Ciliary body, sclera and conjunctiva








































































































































































