A text-book of mental diseases : with special reference to the pathological aspects of insanity / by W. Bevan Lewis.

  • Lewis, William Bevan, 1847-1929.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of mental diseases : with special reference to the pathological aspects of insanity / by W. Bevan Lewis. Source: Wellcome Collection.

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    meshwork] with the neighbouring white medullatecl strands, consti- tuting the so-called formatio reticularis. The white medullated substance of the cord investing this central grey mass is roughly distinguished into an anterior, lateral, and posterior column—the former extending to the outermost roots of the motor nerves : the second from this point back to the attachment of the sensory roots: and the last to the posterior median fissure. These columns are each of them further mapped out into separate tracts, indicated anatomically by a distinct groove on the surface and by a difference in the dimension of their fibres; or by the results of embryological research indicating their medullated development at distinct periods of life; or again, by the facts of the Wallerian degeneration resulting from physiological experimentation or the processes of disease. By one or other of these means we ascertain that at least eight physiological tracts may be distinguished in the white substance of the spinal cord. These may be classed as follows :— Anteriorly—1. Anterior or direct pyramidal tract (also termed the column of TiircJc). 2. Anterior radicular (or root) zone (also termed anterior ground fibres of Flechsig). Laterally— 3. Lateral or crossed pyramidal tract. 4. Direct cerebellar tract. 5. Antero-lateral ascending tract of Gowers (also ex- tending forwards). 6. Lateral limiting layer. Posteriorly 7. Postero-external (or postero-lateral) column (column of Burdach : posterior radicular zone : posterior ground fibres of Flechsig). 8. Postero-internal (or postero-median) column (column ofGoll). Direct PyPcHnidcll TF3,cts.—A certain proportion of the fibres of the anterior pyramids which escape decussation.in the medulla, descend direct on the same side of the cord, forming the tract which more or less completely bounds the anterior median fissure. This anterior pyramidal tract progressively diminishes in size from above down- wards, as it becomes distributed to the anterior cornu of the opposite side by a continuous decussation of its fibres throughout its course along the anterior commissure. It usually extends to the mid-dorsal region, but occasionally passes down as far as the lumbar cord, and is nc to vary very considerably in size for the same levels of the
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