Abstract from notes on the minute structure of the spinal cord / by John B. Trask.
- John Boardman Trask
- Date:
- 1860
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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![[4] verse section. It may be further stated, that the deepest part of the longi- tuduial fissure is wider than any other portion of it, and if cut across, might appear like a canal. Dr. Todd then quotes the observations made by Tiedemann on this sub- ject, in which the latter uses the following language. The spinal marrow represents a hollow cylinder, the thin walls of which are bent backwards, the posterior part representing a longitudinal opening ; for it is hollowed by a groove, termed the canal of the spinal marrow. * On page 708, Dr. Todd reiterates his remarks on the position assigned it by Stilling and Wallach, and concludes as follows. The point is one on which I am not prepared to express a decided opinion at present, and which deserves more extended examination. We have here then the latest competent authorities on both sides, on the existence of the central canal of the cord, and the closing remarks of Dr. Todd most clearly indicate that good reasons were advanced that at least dispel a portion of the doubt which hung over his mind in relation to thi* subject formerly. It is clearly evident from the remarks of Dr. Todd and those of Kolliker, that this canal has not been seen by them in the higher mammalia which had arrived at adult age, or, at any rate, it has never appeared sufficiently appa- rent to those observers except during the periods of fcetal life. As to the remarks of Tiedemann touching this subject, he clearly regarded the posterior terminus of the anterior median fissure as the point at wliich the central canal had been located by observers who had preceded him.f In this Tiedeman was undoubtedly correct, but at the same time he was equally wrong so far as regards the central canal or its true position, for this opening in the cord is at a distance posterior to Tiedemann's opening, more than equal to twice the antero-posterior diameter of the canal, and is separated from the position assigned it by those observers, by tissues materially different from the walls of the anterior fissure. I think there cannot rationally exist a doubt as to the presence of this canal in the spinal cord of the higher ver ebrata. In ihe sheep, such a canal is present beyond all question, and I make this statement without hesitation, for in four hundred and thirty sectio7is of the cord of this animal, 1 have never (except in a single instance in the upper cervical region) seen it absent. I have always found it in any portion of the cord included between the upper cervical and first lumbar vertebra. These experiments were conducted upon the cord removed from nine animals, and in the sections made from the different specimens, I have inva- riably met with the same features at identical points of the organ from each * Lfcipsit g, I8t2. The italics are in the original. + Recently, (1859) Professor Lenhossek has seen a case where, on opening into the cord it wus found that the pia mater where it descends between the anterior columns V-rming the membrane of the aatcrior fissure,^ had become adherent, and thus formed a canal. Prof. Lenhossek also states that he has never seen the central canal closed [in man] as described by Virchow.](https://iiif.wellcomecollection.org/image/b21160211_0006.jp2/full/800%2C/0/default.jpg)
