Sponge: Set up Cornell Notes on pg. 71 Topic: 12.6: Visual Accessory Organs of the Eye Essential...
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Transcript of Sponge: Set up Cornell Notes on pg. 71 Topic: 12.6: Visual Accessory Organs of the Eye Essential...
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
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SightVisual Accessory Organs• eyelids• lacrimal apparatus• extrinsic eye muscles
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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
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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
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Conjunctivitis aka “Pinkeye”: inflammation of the conjunctiva• Caused by bacteria• Highly contagious
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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
Figure 12.23
How does this picture explain why your nose start to run when you are crying?
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• Tear glands secrete excessively when a person is upset or when the conjunctiva is irritated
• Tears spill over the eyelid, nose fills with fluid
The Eyes Natural Protection2m6s
Accessory Structures of the EyeStart: 2m36s
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Figure 12.24 Extrinsic Eye Muscles
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Extrinsic Eye Muscles
Superior rectus• rotates eye up and
medially
Inferior rectus• rotates eye down and
medially
Medial rectus• rotates eye medially
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Extrinsic Eye Muscles
Lateral rectus• rotates eye laterally
Superior oblique• rotates eye down
and laterally
Inferior oblique• rotates eye up and
laterally
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• SR= superior rectus
• IR= Inferior rectus
• MR= Medial rectus
• LR= lateral rectus
• SO= Superior oblique
• IO=Inferior oblique
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• 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