Lesson 2 part 2 Flashcards
Vision (sight)
The perception of objects in the environment by means of light they emit or reflect.
what is light?
Visible part of the electromagnetic spectrum
- Humans can only see wavelengths of light from 400 to 700 nm
what must light do in order to produce a nerve signal?
light must cause a photochemical reaction
What is Ultraviolet (UV) radiation?
<400 nm; has too much energy and destroys macromolecules.
what is infrared (IR) radiation?
> 700 nm; too little energy to cause photochemical reaction, but does warm the tissues
what is the Orbital region?
area around the orbit (eye socket), contains structures that protect and aid the eye.
- Eyebrows
- Eyelids (palpebrae)
what are tarsal glands?
secrete oil that reduces tear evaporation and prevent the eyelids from sticking together
what is Conjunctiva?
- transparent mucous membrane lining eyelids and covering anterior eyeball, except cornea.
- Secretes thin mucous film to prevent drying of eyeball
- Heals quickly
What cranial nerve innervates the Superior oblique?
Cranial nerve 4
what cranial nerve innervates the lateral rectus?
Cranial nerve 6
Cranial nerve 3 innervates which extrinsic eye muscles?
- Superior, inferior, medial rectus
- inferior oblique
Lacrimal caruncle
mass of soft tissue containing glands that make thick secretion that forms gritty deposit (crusties)
what movements do the superior, inferior, medial, and lateral rectus allow the eye to do?
move the eye up, down, medially, and laterally (respectively)
What movements do the superior and inferior obliques allow the eye to do?
turn the eye both towards or away from the nose. they also produce slight elevation and depressions of the eye.
What are the three Tunics (layers)?
1.) Fibrous Layer= outer layer derived from two regions
2.) Vascular Layer= middle layer with three regions
3.) Inner Layer= retina and pigmented epithelium
