Abstract from notes on the minute structure of the spinal cord / by John B. Trask.

  • John Boardman Trask
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: Abstract from notes on the minute structure of the spinal cord / by John B. Trask. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    [14] I have found these corpuscles most abundant in the region in which the pos- terior roots take their origin,—that is to say, for a short distance above and below a line cutting the points of emergence of the posterior roots, and par- allel with the axial lines of the cornua in a horizontal aspect; they are also present in the interspace above and below the emergence of a superior aud inferior pair of afferent nerves, but in an inferior numerical proportion. Up to the present time I have not been able to detect the afferent corpus- cles anterior to a line projected laterally and passing through the middle of the central canal. If they exist anterior to this point, they must have an inclination of plane different from that in which they have thus far been met with. It remains to be demonsirated how far, if at all, the fibres of the afferent cells inosculate with those of the efferent series, and either or both of these with the elements of the ganglionic system. M. Jacubowitsch has made some advanctis in this particular, (see P. M. and S. Jour., No. XXXII, page 319,) but as yet not entirely demons'.rative on this point. His latest re- searches tend to show that at the junction of the fibres of the nerve elements, whether peripheral or central, inosculation ensues with change of function; should this fact be corroborated by future research, the more rational doc- trine of decussation and homology of function must fall to the ground. Tlie Columns of the Cord.—The division of the cord into the different columns is founded on natural lines formed by the commissures and cornua, centrically. In the columns we meet with element structure diflering from that found in either cornua, and in which the round or oval, (the ganglionic cells,) are located. Like the stellate cellules of the anterior cornua, the cor- puscles of the columnar portions of the cord can be seen only in transverse sections. The corpuscles of this system are commonly more largely devel- oped toward the peripheral surface of the cord, and they diminish materially in size as the central portions of the cord are approximated : so much so is this the case, that in close proximity to the cornua, the posterior commissure, and between the lateral processes of the anterior cornua, little else than mere vesicles are to be seen. There seems room for doubt as to whether the gangUonic corpuscles in the cord are not more limited than would at first sight appear, although no really well defined line of demarcation exists between the finer vesicular forms of cells and those so well defined toward the surface of the cord The basis of this doubt is founded on the chemical reactions which are found to ensue in treating this organ, which ai'e constant features ; the coloration is so manifest at these two portions of the columns that we can scarcely i)elieve . the structures alike, nnless we be allowed the latitude of supposing that very much greater delicacy of the walls exists in the cells distant from the periph- ery, which would in some measure account for the difference of color observed under those reactions. A point that militates against difference of structure in the cells of the two regions of the same column, is found in the fact, that under amplification and strong light, the cells which refuse deep coloration appear to me to pos- sess a sameness in structure with the larger and more easily resolved forms
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