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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    Plate XXVIII. figure 30, taken from a photograph of a boiled heart, consists, as was shown by Reid, of three convex portions (rst). Each convex portion is directed from above downwards, and from without inwards, and as it unites above with that next to it, the two when taken together form a conical-shaped prominence (#), which is adapted to one of the three triangular-shaped inter- spaces occurring between the segments of the valve (Plate XXVIII. fig. 17 h). The arterial rings are therefore placed obliquely, the under surface, which gives attachment to many of the fibres of the ventricles anteriorly (Plate XXVIII. fig. 30 dd'\ resting on the rounded oblique border of the ventricular walls (Plate XXVIII. fig. 17 e). The ring surrounding the pulmonary artery, as was pointed out by Reid, is broader, but not quite so thick as that surrounding the aorta, and both are admirably adapted for the reception of the large vessels which, as was shown by that author, originate in three festooned borders. These borders, I am inclined to think, consist of two parts,—an outer (Plate XXVIII. fig. 17 r r'), composed of the outer, and a small portion of the central layer of either the aorta or pulmonary artery; and an inner (t), composed principally of the central and inner layers. The outer border (Plate XXVIII. fig. 18 r), which is the thinner of the two, is attached to the superior and outer margin of one or other of the fibrous rings (g), chiefly by the serous membranes; the inner (Plate XXVIII. fig. 17 t), which projects further in a direction from above downwards, and corresponds to the thickened convex border of the seg- ments (s), to the formation of which it contributes, being attached to the inferior and inner margin (g). These points are well seen, when a vertical section is made of the aorta or pulmonary artery between the segments com- posing the semilunar valves. In such a section (Plate XXVIII. fig. 17), the vessels are observed to be thickened in a direction from above downwards, the thickening beginning at the point where the segments meet above (b), and gradually increasing until the vessels bifurcate (r't). The reverse of this holds true of those portions of the vessels which enter into the formation of the sinuses of Valsalva (Plate XXVIII. fig. 18 i), these being unusually thin, particularly where attached (?•)•* As the thickened portions of the vessels correspond to the fixed margins of the segments (Plate XXVIII. figs. 17 and 35 btn), and extend between them in an arched direction above (c), they give the precise boundaries of the sinuses of Valsalva (Plate XXVIII. figs. 17 and 18 d), and furnish the segments with three fibrous frameworks analogous, in some respects, to the thickenings which occur in similar situations in the veins. These frameworks extend for a, short distance into the segments (Plate XXVIII. fig. 17 b, and fig. 36 n), and assist not only in affording the segments * The several points adverted to are seen to advantage in the whale (Physalus antiquorum, Gray), the aorta of which I had an opportunity of dissecting for the Museum of the Royal College of Surgeons of England.