. A treatise on diseases of the eye . crus; L. lemniscus in crus; R N. red nucleus;///, third nerves. Macular bumllcs not shown. (Starr.) 1 Newtons Optics, Qu. l; 86 ANATOMY fields of vision overlap (a portion of one field common to the other),binocular single vision occurs. In all animals in which the field ofvision in one eye is independent of that of the other eye (fishes, birds, etc.),only crossed nerve fillers have been observed. The nimiber of uncrossedoptic nerve fil)ers is in direct proportion to the area of the field of bin-ocular single vision (area of the field of vision common to b
. A treatise on diseases of the eye . crus; L. lemniscus in crus; R N. red nucleus;///, third nerves. Macular bumllcs not shown. (Starr.) 1 Newtons Optics, Qu. l; 86 ANATOMY fields of vision overlap (a portion of one field common to the other),binocular single vision occurs. In all animals in which the field ofvision in one eye is independent of that of the other eye (fishes, birds, etc.),only crossed nerve fillers have been observed. The nimiber of uncrossedoptic nerve fil)ers is in direct proportion to the area of the field of bin-ocular single vision (area of the field of vision common to both eyes). Inman tiic ])r()portion of crossed to uncrossed nerve fibers is as 3 to 2. Optic Tracts.—The optic nerve fibers, after leaving the chiasm,j)roceed to the basal ganglia by way of the optic tracts. The optic tractsare somewhat flattened, lie on the under surface of the brain, divergeand l)end around the crura cerebri, and pass to the basal ganglia (pri-mary su])cortical optical centres), die external geniculate bodies, the. CONCRtTE CONCEPT Side view of the human brain, showing locahzation of functions. (Charles K. Mills.) anterior corpora quadrigemina, and the posterior portion (pulvinar)of the o])tic thalami. The external geniculate bodies are the most im])or-tant visual ganglia. A passes to the sphincter and acconnnoda-tion group of cells of the nucleus of the third (St. Bernheimer) justbefore the centripetal fibers in the tract reach the external geniculatebody. This is the optic-nerve portion of the pupi/ldrij rejicx arc. Theends of the fibers passing to the basal ganglia become arborescent andapparently terminate in close proximity to neurons, whose axions passinto the posterior part of the internal capsule and reach the corticalvisual area; there they break up into brush-like terminals, which areclosely associated with the ganglion cells of the cortex. Visual impulses,conducted along the tract described, cause excitation of the neurons ofthe cortex
Size: 1892px × 1321px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecteyediseases, bookyear
