Eyeball Flashcards
(25 cards)
Information about the external world is conveyed to the CNS from __
sensory receptors
What are the three concentric tunics of the eye?
- tough external layer (sclera and transparent cornea)
- middle vascular layer (choroid, ciliary body, and iris)
- inner sensory layer (retina)
The ____ communicates with the cerebrum through the posterior optic nerve
retina
___is a perfectly transparent biconvex structure held in place by a circular system of zonular fibers that attach to the ciliary body
lens
The ___surrounds a central opening the__
iris;pupil
The___chamber is between the cornea and the iris
anterior chamber
The___chamber is between the iris and the lens
posterior chamber
Step 1 of eye formation:
In the 4-week embryo epithelial ____ bulge bilaterally from the forebrain, then elongate as the optic stalks bearing optic cups
optic vesicles
Step 2 of eye formation:
Inductive interaction between optic cups and overlying surface ectoderm cause the latter to detach as the ____
intial hollow lens vesicles
Step 3 of eye formation:
The optic stalk develops as the ___
optic nerve
Step 3 of eye formation:
In the inferior groove called the___ encloses the HYALOID VESSELS that supply blood for the developing lens and optic cup
choroid fissure
Step 4 of eye formation:
In the ensuing weeks ___differentiates to form most of the tissue in the eye’s two outer layers and the vitreous
head mesenchyme
Step 4 of eye formation: Ectoderm of the optic cup differentiates as the ___ and ___ form the corneal epithelium
retina and surface ectoderm
Step 4 of eye formation:
When the lens is fully formed, the __ and veins disappear leaving only the blood supply to the retina
Distal hyaloid artery
The fibrous external layer of the eye has two major regions __ and __
Posterior sclera and anterior cornea joined at the limbus
The white posterior five-sixths of the external layer of the eyeball (fibrous layer) is called the__
sclera
_____muscles move the eyes
extraocular muscles
The anteiror 1/6th of the fibrous layer of the eye is the___ and is the transparent and completely avascular layer
cornea
__supports eye shape, protects delicate internsal eye structures, extrinsic eye muscles attach here
Sclera
____Protects anterior surface of the eye, refracts incoming light
Cornea
___supplies nourishmnet to retina, pigment absorbs extraneous light
Choroid
___holds suspensory ligaments that attach to thelens and change the lens shape for far and near vision, epithelium secretes humor
Ciliary body
___controls pupil diameter and thus the amount of light entering the eye
Iris
___absorbs extraneous light, provides vitamin A for photoreceptor cells
Pigmented Layer
