Visual System

Question 1

Development of Eye

Answer 1

Optic vesicle forms from neural tissue outgrowth from dienceph, then lens placode forms from ectoderm so its really more epithelial, these fold back on selves to form 2-layered optic cup that is an area of weakness (detached retina)

Question 2

3 Layers of Globe

Answer 2

Fibrous, vascular, and neural

Question 3

2 Structures of Fibrous Tunic

Answer 3

Cornea and Sclera

Question 4

Layers of Cornea

Answer 4

Have multicellular epithelial outer layer, very thick middle layer, and unicellular inner endothelial layer

Question 5

LASIX

Answer 5

Incise corneal epithelium and fold back, then burn off layers of thick middle layer to change light refraction

Question 6

5 Structures of Vascular Layer

Answer 6

Choroid
Ciliary Body
Iris
Lens
Vitreous Body

Question 7

2 Functions of Choroid

Answer 7

Posteriorly placed w/ lots of vascular for retina and highly pigmented w/ melanocytes to prevent light bouncing

Question 8

3 Functions of Ciliary Body

Answer 8

Ciliary processes radiate medially as suspensory ligaments of lens
Aq humor production
Ciliary muscle for accomodation

Question 9

Iris Contents/Function/etc

Answer 9

Heavily pigmented cells that form pupil, has dilator pupillae (longitudinal) and constrictor pupillae (circular) muscles. Melanocyte density determines color. Main function to control amount of light entering

Question 10

Lens Main Function

Answer 10

Focus light onto retina

Question 11

10 Distinct Layers of Neural Tunic (Superficial to Deep)

Answer 11

Inner limiting membrane
Optic nerve fiber layer
Ganglion cell layer - ganglion cell nuclei
Inner plexiform layer
Inner nuclear layer - bipolar, horizontal, amacrine nuclei
Outer plexiform layer
Outer nuclear layer - rod and cone nuclei
Outer limiting membrane
Layer of rods and cones
Pigment epithelium for melanin and nutrition/support

Question 12

Amacrine Nuclei

Answer 12

Modify visual signal before event sent to optic nerve

Question 13

Macula Lutea/Fovea Centralis

Answer 13

Big area/specific spot inside it where you have a lot of cones and limited nuclei/vessels blocking source

Question 14

Optic Tracts

Answer 14

After they cross in the chiasm, contains the opposite visual field consisting of nasal portion of opposite eye and temporal portion of ipsilateral eye

Question 15

Lateral Geniculate

Answer 15

Takes fibers from optic tract, passes through six layers of neuronal cell bodies, and sends out optic radiations (geniculo-calcarine bodies)

Question 16

Optic Radiations (Geniculo-calcarine bodies)

Answer 16

Either go above calcarine fissure (area 17) through parietal carrying lower visual field, or below calcarine fissure as Meyer’s loop through temporal carrying upper visual field. Macular vision projects to caudal occipital cortex

Question 17

2 Projections out FROM Occipital Cortex

Answer 17

Where? - to parietal, analysis of motion and spatial relations
What? - to temporal, analysis of form and color

Question 18

Pathway for Direct/Consensual Pupillary Light Reflexes and Accomodation

Answer 18

Come in, go through optic tract, synapse in superior colliculus, go to both Nuclei of Edinger-Westphal as sensory and synapse out as motor, down III as pregang parasymp, then synapse at ciliary ganglion, then activate either sphincter pupillae muscle or ciliary muscle

Question 19

Optic Nerve Lesion

Answer 19

Loss of vision in ipsilateral eye

Question 20

Optic chiasm lesion

Answer 20

Bitemporal (heteronymous) hemianopsia (lateral visual field in each eye gone)

Question 21

Optic Tract Lesion

Answer 21

Homonymous hemianopsia (one side visual field gone in each eye)

Question 22

Optic Radiation Lesion

Answer 22

Quadrantanopsia (1 quadrant in each eye gone)

Question 23

Occipital Cortex Lesion

Answer 23

Homonymous hemianopsia with macular sparing