File:Hand-book of physiology (1892) (14578907497).jpg

Identifier: handbookofphysio00bake (find matches)
Title: Hand-book of physiology
Year: 1892 (1890s)
Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed
Subjects: Physiology Human physiology
Publisher: London : John Murray
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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um with the other. They are called the inferior or arcuatecommissure. The optic tract thus formed then passes backwardsand terminates in three distinct nuclei, viz., the pulvinar of theoptic thalamus, the median corpus quadrigeminum and the lateralcorpus geniculatum. These nuclei waste if the eyes are removed CH. XVI.) THE OPTIC NERVE-FIBRES. 659 from an adult animal; and if from a newly born animal theydo not develope. The optic chiasma in its course gives off fibreswhich are connected with the nucleus of the third nerve It appears that some of the fibres of the optic tract passdirectly into the cerebral cortex without joining with the opticthalamus, corpus quadrigeminum or corpus geniculatum. It was shown above that the fibres of the cerebral cortex,known as the optic radiation, pass from the occipital region tothe three nuclei about which we are speaking, viz., into thepulvinar of the optic thalamus, the anterior corpus quadri-geminum and lateral corpus geniculatum, and it is known
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riff. 386.—Mesial aspect of human cerebral hemisphere to indicate position of centres.The exact position of the centres will be seen by comparing this figure with figure 372. that when the occipital cortex is removed, these three waste.It has been further shown that in a newly born animal theremoval of such a region is followed by imperfect developmentof the parts in question. If one optic nerve be divided blindness of the correspondingeye results, but if one optic tract be divided there is a half blind-ness, which is called hemianopsia, hemianopia, or hemiopia, right orleft, according as the right or left field of vision is cut off. It ishighly probable that the occipital lobe (figs. 382, 386), and par-ticularly the cuneus, is concerned as a so-called visual centre, sincenot only is it connected with the optic nerves, as we have seen,but also because the removal of the right occipital lobe in ananimal (monkey), is followed by left hemiopia, removal of the leftby right hemiopia, and

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