Visual Pathway and Visual Fields

Question 1

describe how retinal fibers are arranged as they gather at the optic disc?

Answer 1

as on the retina, but with macular fibers at temporal side, crowding others to the nasal side
(incomplete basketball lines)

Question 2

describe how retinal fibers are arranged in the optic nerve?

Answer 2

the macular fibers take center stage
everything else is as it was on the retina
(superior temporal fibers are superior temporal, etc)

Question 3

describe the fiber arrangement in the optic tract?

Answer 3

nasal fibers (including nasal half of macular fibers), cross at the optic chiasm (only the temporal half of the macular fibers remains)
the inferior part of the temporal fibers goes to the lateral side, and the superior part goes to the medial side (Lateral goes to Lower)

Question 4

describe the fiber arrangement at the LGN?

Answer 4

same as in the optic tract

Question 5

describe the fiber orientation in the optical radiations?

Answer 5

lateral fibers of LGN go lower (inferior)

medial fibers go superior

Question 6

describe orientation of fibers in striate cortex?

Answer 6

macular fibers that correspond to temporal retina go toward posterior pole (straddle cuneus gyrus and lingual gyrus)
lower fibers go to lingual gyrus, upper go to cuneus gyrus

Question 7

where do lower fibers of optic radiations go to?

Answer 7

“loop” into temporal lobe

Question 8

what is the simplified way to remember fiber arrangement along the visual pathway?

Answer 8

Optic disc: basketball, with macular fibers in left half-circle
optic nerve: macular to middle, all else back to retina arrangement
optic tract: croissant, with nasal fibers gone (crossed) and Lower retinal fibers Lateral
LGN: same as for optic tract (still a croissant)
optic radiations: vertical oval, Lower fibers Low again
striate cortex: macular to posterior pole (spanning gyri), and lower retianl fibers to lingual gyrus