1. Sponge: Set up Cornell Notes on pg. 71 Topic: 12.6: Visual Accessory Organs of the Eye Essential Questions: 1.What is the function of the lacrimal apparatus? Describe the pathways of the tears. 2.1 Atoms, Ions, and Molecules 12.6: Visual Accessory Organs of the Eye

2. 2 Sight Visual Accessory Organs eyelids lacrimal apparatus extrinsic eye muscles

3. 3 Eyelid (palpebra) is composed of four layers: 1. Skin Thinnest skin of the body Protection 2. Muscle orbicularis oculi (orbic-u-laris) – closes lid levator palperbrae superioris – opens lid 3. Connective tissue tarsal glands – secrete oil onto eyelashes Helps keep lids from sticking together

4. 4 4. Conjunctiva (Con-junct-i-va) mucous membrane; lines eyelid and covers portion of eyeball Lubricates eye Prevents microbes from entering the eye Protection Contain an enzyme that has antibacterial properties Reduces eye infections Thin/Freely movable/ transparent

5. 5 Conjunctivitis aka “Pinkeye”: inflammation of the conjunctiva Caused by bacteria Highly contagious

6. 6 Lacrimal Apparatus Lacrimal gland lateral to eye secretes tears 1. Canaliculi (cana-lik-u-lie) collects tears 2. lacrimal sac collects tears from canaliculi 3. nasolacrimal duct collects tears from lacrimal sac and empties tears into nasal cavity

7. Figure 12.23 How does this picture explain why your nose start to run when you are crying?

8. 8 Tear glands secrete excessively when a person is upset or when the conjunctiva is irritated Tears spill over the eyelid, nose fills with fluid

9. The Eyes Natural Protection 2m6s Accessory Structures of the Eye Start: 2m36s 9

10. Figure 12.24 Extrinsic Eye Muscles

11. 11 Extrinsic Eye Muscles Superior rectus rotates eye up and medially Inferior rectus rotates eye down and medially Medial rectus rotates eye medially

12. 12 Extrinsic Eye Muscles Lateral rectus rotates eye laterally Superior oblique rotates eye down and laterally Inferior oblique rotates eye up and laterally

13. 13 SR= superior rectus IR= Inferior rectus MR= Medial rectus LR= lateral rectus SO= Superior oblique IO=Inferior oblique

14. 14 The motor units of the eye muscles have the fewest muscle fibers of any muscles in the body Move with great precision Eyes move together Align when looking at something