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THE PYRAMID TRACT IN THE STRIPED GOPHER (SPERMO‐PHILUS TRIDECEMLINEATUS (MITCHILL))
Author(s) -
Simpson Sutherland
Publication year - 1915
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0370-2901
DOI - 10.1113/expphysiol.1915.sp000191
Subject(s) - anatomy , medulla oblongata , decussation , pons , spinal cord , medulla , lumbar , biology , dorsum , pyramidal tracts , central nervous system , neuroscience
In the striped gopher (Spermophilus tridecemlineatus) the course of the pyramid tract is traceable from the motor cortex by the method of secondary degeneration with Marchi staining. In the mid‐brain, pons, and upper part of the medulla oblongata the tract occupies the usual position in the crusta, pontine bundles, and ventral pyramid, the degeneration being confined to the side of the lesion. In the lower part of the medulla oblongata the fibres cross to the opposite side and take up a position in the funiculus cuneatus, forming there a well‐defined tract. The decussation appears to be complete, no fibres passing to the same side but all into the dorsal column of the opposite side. In this position the tract runs caudalwards and can be traced as far as the third lumbar segment, where it is represented by a very few scattered fibres. Beyond this level it cannot be followed. On following the tract downwards through the spinal cord many fibres are found to disappear in the first and second cervical segments, presumably by passing into the grey matter at these levels. Very few fibres reach as far as the lumbar region.