Visual System Flashcards Preview

Neuroanatomy > Visual System > Flashcards

Flashcards in Visual System Deck (23):
1

Development of Eye

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)

2

3 Layers of Globe

Fibrous, vascular, and neural

3

2 Structures of Fibrous Tunic

Cornea and Sclera

4

Layers of Cornea

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

5

LASIX

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

6

5 Structures of Vascular Layer

Choroid
Ciliary Body
Iris
Lens
Vitreous Body

7

2 Functions of Choroid

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

8

3 Functions of Ciliary Body

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

9

Iris Contents/Function/etc

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

10

Lens Main Function

Focus light onto retina

11

10 Distinct Layers of Neural Tunic (Superficial to Deep)

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

12

Amacrine Nuclei

Modify visual signal before event sent to optic nerve

13

Macula Lutea/Fovea Centralis

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

14

Optic Tracts

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

15

Lateral Geniculate

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

16

Optic Radiations (Geniculo-calcarine bodies)

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

17

2 Projections out FROM Occipital Cortex

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

18

Pathway for Direct/Consensual Pupillary Light Reflexes and Accomodation

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

19

Optic Nerve Lesion

Loss of vision in ipsilateral eye

20

Optic chiasm lesion

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

21

Optic Tract Lesion

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

22

Optic Radiation Lesion

Quadrantanopsia (1 quadrant in each eye gone)

23

Occipital Cortex Lesion

Homonymous hemianopsia with macular sparing