Eye (Ch. 19)

Question 1

Vision

Answer 1

Dominant sense in humans: 70% of sensory receptors are in eyes, 40% of cerebral cortex devoted to processing visual info.

Question 2

What are the 4 cranial nerves that are associated with vision?

Answer 2

Optic (CN 2)
Oculomotor (CN 3)
Trochlear (CN 4)
Abducens (CN 6)

Question 3

List the structures of the eye

Answer 3

Lateral angle (outer corner of eye)
Inferior palpebrum (eyelid)
Lacrimal Caruncle
Medial Angle (inner eye corner)
Eyelashes
Superior Palpebrum (eyelid)

Question 4

What is the palpebrum?

Answer 4

The eyelid

Question 5

What do the eyelids do?

Answer 5

Protect the eyes

Question 6

What separates the upper and lower lids? Where do they meet?

Answer 6

Palpebral fissure separate upper and lower lids

Pangles are where they meet

Question 7

What is the Conjunctiva?

Answer 7

Mucus membrane covering inner eyelids and sclera (NOT THE CORNEA!)

Question 8

Lacrimal Apparatus

Answer 8

Lacrimal glands supply eyes with lacrimal fluid (tears)
Lacrimal fluid has immune fxns (mucus, antibodies, enzymes)

Drains into lacrimal sac and then nasolacrimal duct and nasal cavity = runny nose when crying

Question 9

List the 6 extrinsic eye muscles.

Answer 9

Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Superior oblique
Inferior oblique

Question 10

What cranial nerve innervates the lateral rectus?

Answer 10

Abducens (CN 6)

Question 11

What cranial nerve innervates the superior oblique?

Answer 11

Trochlear (CN 4)

Question 12

What cranial nerve innervates the medial rectus, superior rectus, inferior rectus, and inferior oblique?

Answer 12

Oculomotor (CN 3)

Question 13

Fxn of lateral rectus?

Answer 13

Abduct eye

Question 14

Fxn of medial rectus?

Answer 14

Adduct eye

Question 15

Fxn of superior rectus?

Answer 15

Elevate and adducts eye

Question 16

Fxn of inferior rectus?

Answer 16

Depresses and adducts eye

Question 17

Fxn of inferior oblique?

Answer 17

Elevates and abducts eye

Question 18

Fxn of superior oblique?

Answer 18

Depresses and adducts eye

Question 19

Eye Structure: Fibrous Layer

Answer 19

Most external

Includes Sclera and Cornea

Question 20

Fibrous Layer: Sclera

Answer 20

Tough, outer covering of eye (white of eye). Protects eyeball

Question 21

Fibrous Layer: Cornea

Answer 21

Continuation of sclera, transparent, allows right into eye, acts as fixed lens for focusing

*Cornea is avascular but lots of nerve endings

Question 22

Eye Structure: Vascular Layer

Answer 22

Middle layer

Includes Choroid, Ciliary body/muscles, Iris, and Pupil

Question 23

Vascular Layer: Choroid

Answer 23

heavily pigmented vascular layer. Melanin helps absorb light

Question 24

Vascular Layer: Ciliary body/muscles

Answer 24

encircle lends, control lens shape for precise focusing

Question 25

Vascular Layer: Iris

Answer 25

Colored part of eye, regulates light entering eye

Question 26

Vascular Layer: Pupil

Answer 26

A space, not a structure! Allows light to enter eye. Pupil contracts in bright light (parasympathetic innervation) Pupil dilates in low light (sympathetic innervation)

Question 27

Eye Structure: Inner Layer

Answer 27

``` Retina: converts light to nerve impulses Optic Nerve (CN 2): transmits nerve impulses to brain ```

Question 28

Retina

Answer 28

Innermost layer of eyeball, photosensitive (sensitive to light) 2 layer: - -pigmented layer = melanocytes. Absorb light and keep it from scattering - -neural layer - nervous tissue w/ photoreceptive cells

Question 29

Photoreceptor Cells

Answer 29

Rods: work best in dim light Cones: perceive red, blue, green. Cones great for color vision, bright light. Absorption spectra overlap, so combination of stipulations of cones - different colors

Question 30

Retina: Macula Lutea, Fovea Centralis, and Optic Disc

Answer 30

Macula Lutea: area of concentrated cone cells at posterior pole Fovea Centralis: area of only cone cells inc enter of macula lute. Highest visual acuity Optic Disc: blind spot, location where optic nerve attaches. No photoreceptor cells

Question 31

What is the blind spot in the eye?

Answer 31

Optic Disc

Question 32

Lens

Answer 32

avascular, transparent disk, shape can be changed to adjust focus

Question 33

Anterior Chamber

Answer 33

in front of lens has aqueous humor

Question 34

Posterior Chamber

Answer 34

behind lens. Has vitreous humor (jellylike). Most volume of eye

Question 35

Vitreous and Aqueous humor help maintain ___ ___?

Answer 35

Vitreous and Aqueous humor help maintain intra-ocular pressure

Question 36

Incoming Images

Answer 36

Since lens of eye is convex, images are upside down and reversed. Cerebral cortex flips image back to "normal" so we can see properly