Secondary degeneration following unilateral lesions of the cerebral motor cortex / by Sutherland Simpson.
- Sutherland Simpson
- Date:
- 1902
Licence: In copyright
Credit: Secondary degeneration following unilateral lesions of the cerebral motor cortex / by Sutherland Simpson. Source: Wellcome Collection.
Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.
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![part, and of the ci-ossed pyramidal tract in tlie spiiial cord. Wlien the motor decussation proper is reached, bundles of fibres are ob- served to come off fi'om the posterointernal angle of the degenerated p^Tamid, and after crossing the middle line, to pass backwards towards the lateral portion of the grey matter around the central canal, and then to curve more outwards and become lost as they turn caudal- wards in their passage towards the lateral column (crossed pyramidal tract) of the spinal cord. I have seen very few fibres passing in a similar direction fi'om the degenerated pyramid towards the same side (homo- lateral) until the middle of the decussation is reached, and from this level downwards these homolateral fibres increase in number (fig. 5. pi. XVI). Eedlich [6] says these homolateral fibres come off in greatest abun- dance from the middle -/^^^^ of the decussation. When this region of the medulla oblongata (pyramidal decussation) is cut serially, they are missed in several consecutive sections and then appear again. This is due to the fact that they come off in small bundles compar- atively widely separated from each other vertically. The ratio be- tween the decussating and non-decussating fibres vary considerably in the different animals, but the relative numbers can only be known by counting the fibres on each side in sections thi'ough the upper cer- vical cord, and not by comparing the two sides in any one section through the decussation. Down to the level of the pyramidal decussa- tion a few black dots had been observed in transverse sections of the pyramidal tract of the side opposite to the lesion in several of the earlier animals, but whether these represent degenerated fibres or are merely accidental it is difficult to be certain. In material pre- pared later in the research when more experience had been gained in the technique, the degeneration was almost invariably wholly uni- lateral down to the level of the decussation. In the cervical region of the spinal cord the degenerated crossed pyramidal tract occupies a comparatively small rounded area (rela- tively much smaller tlmn in the monkey) in the posterior part of the right lateral column, close to the antero-lateral aspect of the posterior horn, and not reaching the margin of the section. From this tract, in many of the cases, a few degenerated filires are seen to pass in to-](https://iiif.wellcomecollection.org/image/b21455727_0015.jp2/full/800%2C/0/default.jpg)
