Selections in pathology and surgery, or, An exposition of the nature and treatment of local disease : exhibiting new pathological views, and pointing out an important practical improvement, illustrated by cases / by John Davies.

  • John Davies
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Selections in pathology and surgery, or, An exposition of the nature and treatment of local disease : exhibiting new pathological views, and pointing out an important practical improvement, illustrated by cases / by John Davies. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    MECHANISM AND erroneous notions respecting the muscularity of these vessels have been entertained by authors and by anatomists generally. In order to be able to determine this point it is necessary to define what are meant by muscular fibres. It must be admitted that a muscle, like all other bodies, has certain distinct characters which determine it to be what it is. It is composed of a greater or less number of elastic-fibres, placed parallel to each other; and these fibres are bound together, at intervals, by striae or smaller fibres, each being separated from the rest by a very small portion of cobweb- like tissue. The primitive or simple fibres are gathered together into fasciculi or small bundles, surrounding each of which there is a larger quantity of cellular tissue than is found around every simple fibre. The muscle is composed of a number of these fasciculi or compound fibres, and, like them, the whole body of it is invested in a coat of cellular tissue. This is the character of muscular structure. Now, the next question is, do we find any thing in the coats of the arteries corresponding wfith the above definition ? We presume not; that is, we presume so upon a very strict examination of their structure. Including the external coat, which is composed of con- densed cellular membrane, an artery is made up of three layers or coats. Tlie innermost layer, which, on one side, presents a jDolished surface for the blood to move on, is formed of a highly elastic tissue, l)ut nothing like muscular fibres are discoverable in it. The next layer is also considerably elastic, but less so than the innermost coat. This being the coat usually considered muscular, we have paid much attention to its structure, but, upon the minutest examination, nothing could be discovered in its texture to correspond with the fibres of muscle. Tlie mistake may have occurred from con- sidering the fibrous processes which unite it to the outermost coat as muscular fibres; for, with the exception of these, scarcely any tissue in the body presents less the appearance of muscle. The outermost layer is likewise elastic, Isut its elasticity is inferior even to that of the middle coat, though its toughness considerably exceeds that of the latter. An artery, thus composed of its different layers of coats, is elastic to a considerable degree, but the elasticity does not depend upon muscular fibres. Indeed, such a structure, as unll be pointed out hereafter, would be inconsistent with the functions which these vessels are destined to perform in the animal economy. It may be noticed that the elasticity of the arteries is somewhat greater in the longitudinal than in the circular or transverse direction. ^ ith regard to the veins, they have been deemed almost
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