The anatomy of the nervous system, from the standpoint of development and function . of the medial division of the dorsal rootrun for considerable but varying distances in the posterior funiculus; some fromeach root reach the medulla oblongata, others terminate at different levels in thegray matter of the spinal cord. At the level of their entry into the cord thesefibers occupy the lateral portion of the fasiculus cuneatus; but in their coursecephalad, as each successive root adds its quota, those from the more caudalroots are displaced medianward. In this way the longer fibers come to occupyt
The anatomy of the nervous system, from the standpoint of development and function . of the medial division of the dorsal rootrun for considerable but varying distances in the posterior funiculus; some fromeach root reach the medulla oblongata, others terminate at different levels in thegray matter of the spinal cord. At the level of their entry into the cord thesefibers occupy the lateral portion of the fasiculus cuneatus; but in their coursecephalad, as each successive root adds its quota, those from the more caudalroots are displaced medianward. In this way the longer fibers come to occupythe medial portion of the posterior funiculus (Fig. 71). In the cervical region 95 96 THE NERVOUS SYSTEM the long ascending fibers from the sacral, lumbar, and lower thoracic rootsconstitute a well-defined medially placed bundle, the fasciculus gracilis, sepa-rated from the rest of the posterior funiculus by the posterior intermediateseptum. Those of the long ascending fibers, which finally reach the brain,terminate in gray masses in the posterior funiculi of the medulla oblongata. Fig. 70.—Bifurcation of the dorsal root fibers within the spinal cord into ascending anddescending branches, which in turn give off collaterals; the termination of some of these col-laterals in synaptic relation to cells of the posterior gray column. (Cajal, Edinger.) (nucleus of the funiculus gracilis and nucleus of the funiculus cuneatus). Sincethe number of these long ascending branches must increase from below upwardit is easy to understand the progressive increase in size of the posterior funiculusfrom the sacral to the cervical region (Fig. 60). The fasciculus gracilis and fasciculus cuneatus are composed for the most illil K I R \i fS 01 NIK SPINAL CORD 97 / i. gracilisI a i Utieatui part of these ascending branches of the dorsal root fibers, the former containIng those which have the Longest intramedullary course. The descending branches of the fibers of the medial division of the dorsalmot
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectnervoussystem, bookye
