. A text-book of human physiology . ion,and is found in the anterior columns of the cord. The tracts thus far descril)ed—GolVs and Burdaclis columns, the dorso-and ventrolateral cerebellar tracts, the pyramidal tracts and the efferent tractsjust mentioned—all represent connecting pathways between distant portionsof the central nervous system. Flateau has drawn attention to the fact thatthey tend to occupy the border zone of the white columns in the cord; thatAvhilo they may at certain levels be displaced from this zone, they alwaysreturn to it at the first opportunity and thereafter keep their
. A text-book of human physiology . ion,and is found in the anterior columns of the cord. The tracts thus far descril)ed—GolVs and Burdaclis columns, the dorso-and ventrolateral cerebellar tracts, the pyramidal tracts and the efferent tractsjust mentioned—all represent connecting pathways between distant portionsof the central nervous system. Flateau has drawn attention to the fact thatthey tend to occupy the border zone of the white columns in the cord; thatAvhilo they may at certain levels be displaced from this zone, they alwaysreturn to it at the first opportunity and thereafter keep their position untilthey turn into the gray matter. The inner zones of the white columns are occupied in the main by slwrf-fibered tracts connecting different levels of the cord. Some of these tractsarise from widely distributed multipolar cells (column cells), which send axiscylinders into the antero-lateral column of the same or of the opposite side. 594 PHYSIOLOGY OF THE NERVE CELL AND THE SPINAL CORD Truf!/( •^P ^nee ..^ Ankle. Fig MuscI CONDUCTING PATHWAYS IN THE SPINAL CORD 595 Here collaterals are given off which again betake themselves to the graymatter and there end in terminal arborizations about other cells. Other fibersof this class run in the posterior columns, being found chiefly in the mostventral section. Still other cells, whose axis cylinders break up immediately without pass-ing to any well-defined pathway, serve as connecting linls between differentelements at the same level. Such cells are found scattered throughout everycross section, but are particularly abundant in the vicinity of the posteriorhorn. It will be apparent from what has gone before that the antero-lateral col-umns of the spinal cord are the most important. In these we have, besidesthe particularly prominent crossed and direct pyramidal tracts: the dorso-and ventrolateral cerebellar tracts, which are among the most importantafferent conducting pathways to the brain; the rubrospinal, the tect
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