Secondary degeneration following unilateral lesions of the cerebral motor cortex: an experimental research

Abstract

The following thesis contains a record of the results anatomical and physiological of a number of experiments undertaken at the suggestion of Professor Schafer with a view to determine the path pursued by the fibres of the pyramidal tract in their course from the large pyramidal cells in the cerebral motor cortex to their termination in the lower levels of the brain and spinal cord, but more particularly their mode of ending in relation to the nuclei of the cranial nerves in the mid-brain, pons and medulla oblongata. Although this - the motor path - has been more carefully investigated and is probably better understood than any other tract or path in the central nervous system, still much remains to be discovered, especially regarding the terminal connections of its fibres with the motor nuclei of the cranial nerves and with the cells in the anterior horns of the spinal cord. Writing on this matter, Barker says:- "The exact place where the fibres for these nuclei" (cranial motor nuclei) "leave the main bundles" (of the pyramidal tract) "and the exact path which they follow to the nuclei have not as yet been fully determined." . . . "The statement that nerve fibres from these bundles do pass to these nuclei is based mainly, but not solely, upon clinical experience, physiological experiment, and analogy." That is to say, the anatomical connections of the fibres of the pyramidal tract with the cells of the anterior cornua of the spinal cord and of the cranial motor nuclei have never yet been satisfactorily established, and it was with the object of throwing some light if possible on this subject that the work embodied in the present thesis was undertaken.