1. The Eye

2. Extrinsic Eye Muscles Six skeletal muscles that move the eyeball
Superior rectus- rotates eye up and medially
Inferior rectus- rotates eye down and medially
Medial rectus- rotates eye medially
Lateral rectus- rotates eye laterally
Superior oblique- rotates eye down and laterally
Inferior oblique- rotates eye up and laterally

4. Eye Structure and Function
3 layers- outer fibrous tunic, middle vascular tunic, inner nervous tunic
1. Outer- Cornea- anterior portion transparent, light transmission, light refraction Sclera- posterior portion, opaque, protection
Lens-Transparent, lies behind iris, largely composed of lens fibers, elastic, held in place by suspensory ligaments of ciliary body

5. 2. Middle- Iris- anterior, pigmented, controls light intensity Ciliary body- anterior, pigmented, holds lens, moves lens for focusing Choroid coat- provides blood supply, pigments absorb extra light
Anterior of eye filled with aqueous humor.

7. 3. Inner- retina
contains visual receptors
continuous with optic nerve
ends just behind margin of the ciliary body
composed of several layers
fovea centralis –produces sharpest vision
optic disc – the raised disk on the retina at the point of entry of the optic nerve, lacking visual receptors and so creating a blind spot.
vitreous humor – thick gel that holds retina flat against choroid coat

8. How We See Photoreceptors:
Rods- produce colorless vision, produce outlines of objects
Cones- provide vision in bright light, produce sharp images, produce color vision