Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 600 PHYSIOLOGY Ventrally to the pyramidal tracts there is a fairly compact group of fibres which degenerate downwards. This is known as the pre-pyramidal or rubro- spinal tract, since its fibres can be traced up to the cells in the red nucleus, a mass of grey matter in the mid-brain situated ventrally to the nucleus of the third nerve. There are also some scattered fibres in the antero-lateral column, which degenerate in the downward direction. These were formerly supposed to be derived from the
Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 600 PHYSIOLOGY Ventrally to the pyramidal tracts there is a fairly compact group of fibres which degenerate downwards. This is known as the pre-pyramidal or rubro- spinal tract, since its fibres can be traced up to the cells in the red nucleus, a mass of grey matter in the mid-brain situated ventrally to the nucleus of the third nerve. There are also some scattered fibres in the antero-lateral column, which degenerate in the downward direction. These were formerly supposed to be derived from the cerebellum of the same side, but it has been shown that they are in all probability derived from Deiters' nucleus in the medulla, which stands as a downward transmitting station between Fig. 276. spL Diagram (from Schafer) showing the ascending (right side) and the descending (left side) tracts in the spinal cord. 1. Crossed pyramidal. 2. Direct i^yramidal. 3. Antero-lateral descending. 3a. Spino-olivary descending (bundle of Helweg). 4. Pre-pyramidal (rubrospinal). 5. Comma. 6. Postero-mesial. 7. Postero-lateral. 8. Lissauer's tract. 9. Dorsal (ascending) cerebellar. 10. Antero-lateral ascending, Septo-marginal. Dorsal root zone. a. Anterior horn cells, i. Intermedio- lateral horn. p. Cells of posterior horn. d. Clarke's column. The fine dots represent the situation of the ' internuncial' or 'endogenous ' fibres of the|spinal cord. cerebellum and cord. These are sometimes known as the vestibulo-spinal tract. Beside these tracts there is a little collection of fibres in the posterior columns which degenerates for a few segments of the cord heloio a transverse lesion (the ' comma ' tract). They consist largely of fibres derived from the posterior roots, which divide into ascending and descending branches as they enter the cord, but also contain probably certain fibres derived from cells in the cord and serving to connect one segment of the cord with another.
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