On the relations, structure, and function of the valves of the vascular system in Vertebrata / by James Bell Pettigrew.

Date:
1864
Catalogue details

Licence: Public Domain Mark

Credit: On the relations, structure, and function of the valves of the vascular system in Vertebrata / by James Bell Pettigrew. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    although a perfect closure may be effected by purely mechanical means in the dead vein, it is more than probable that in the living one, the contraction of the coats of the vessel exercises a regulating influence. Structure of the Arteries and Arterial Valves. The coats of the arteries, as is well known, are thicker than those of the veins, while the layers composing them are more numerous. The external coat, accord- ing to Henle, consists of an outer layer of areolar tissue in which the fibres run obliquely or diagonally round the vessel, and an internal stratum of elastic tissue; the middle coat in the largest arteries, according to Rauschel, being divisible into upwards of forty layers. The layers of the middle coat consist of; pale, soft, flattened fibres, with an admixture of elastic tissue, the fibres and elastic tissue being disposed circularly round the vessel. The internal coat is composed of one or more layers of fibres, so delicate that they constitute a transparent film, the film being perforated at intervals, and lined with epithelium. The arteries, as might be expected from their structure, and as was proved by the admirable ex- periments of John Hunter, whose beautiful preparations I have had an oppor- tunity of examining, possess a high degree of elasticity and vital contractility, and are extensible and retractile both in their length and breadth; the power of recovery, according to that author, being greater in proportion as the vessel is nearer the heart. From this it follows that the pulmonary artery and aorta are most liable to change in dimensions. As, however, any material alteration in the size of the pulmonary artery and aorta might interfere with the proper function of the semilunar valves situated at their orifices, it is curious to note that the great vessels arise from strong and comparatively unyielding fibrous rings. These rings (particularly the aortic one) are so dense as to be almost cartilaginous in consistence, and Professor Donders* has lately discovered, that they contain stellate corpuscles similar in man}' respects to those stellate and spicate corpuscles, found in many forms of cartilaginous tumours. They have been more or less minutely described by Valsalva,! Gerdy4 Dr John Reid,§ and Mr W. S. Savory, || and merit attention because of their important relations to the segments of the semilunar valves. The following description of the aortic and pulmonic fibrous rings, has been drawn up chiefly from the examination of a large number of human hearts. Each ring, as will be seen by a reference to * Onderzockingeu betrekkeligh den bouw van het menchclijke hart, in Nederlandsch Lancet for March and April 1852. f Opera Valsalva, torn. i. p 129. T Journal Complimentaire, torn. x. § Cyc. Anat. and Phy. article Heart, pp. 588, 589. London, 1839. |] Paper read before the Royal Society in December 1851.