On the arrangement of the muscular fibres in the ventricles of the vertebrate heart : with physiological remarks / by James Bell Pettigrew.

Date:
1864
Catalogue details

Licence: Public Domain Mark

Credit: On the arrangement of the muscular fibres in the ventricles of the vertebrate heart : with physiological remarks / 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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    when explaining the construction of the right ventricle of the mammal, to discuss at length the peculiar fleshy valve which in the bird occupies the right auriculo-ventri- cular orifice. This valve constitutes, I may remark, the distinguishing feature between the ventricles of the bird and mammal. VENTRICLES OF THE MAMMAL. The ventricles in the mammal are subject to considerable variation as regards shape. In the porpoise they have their dorsal or posterior surface flattened, and their anterior surface very slightly rounded, as in the higher reptiles. In the mysticetus the ventricles are compressed laterally, and so resemble those of the higher fishes. In the dugong and rhytina, they are characterized by having two very distinct and widely separated apices, as shown in Plate XIV. fig. 42. The general appearance presented by the ventricles of the mammal is familiar to all, it being that of an irregular cone slightly twisted upon itself. The posterior surface of the cone is flattened, as in the ventricle of the fish and reptile, and on account of the obliquity of the base is shorter than the anterior surface. The anterior surface, which is divided into two by an oblique sulcus or furrow, is, on the contrary, rounded and prominent, and presents a characteristic convex outline. Two margins or borders are usually described—a right inferior or acute margin (margo acutus), and a left superior or obtuse one (margo obtusus). As, however, these margins vary somewhat in different hearts, no general description concerning them can be strictly applicable. In the hearts of the ass, American elk, and deer tribe generally, the ventricles are rounded and taper towards the apex, so that the right margin appears almost as obtuse as the left; while in those of the armadillo and carnivora, the ventricles, which are not taper but purse- shaped, have likewise the right side very obtuse*. The idea therefore of an acute margin ought perhaps to be confined to the right side of the human heart and a few others, such as the heart of the seal and hog, both of which bear a considerable resem- blance to that of man. The base of the cone formed by the ventricles of the mammal, as is well known, is perforated by four openings. These openings are surrounded by fibrous rings, and con- duct to conical-shaped spiral cavities f, which vary somewhat in size according as the earner columnar are absent % or present, and the musculi papillares feebly or fully developed. Considered as a muscle, the heart, and especially the ventricular portion of it, is peculiar. Being in the strictest acceptation of the term an involuntary muscle, its fibres nevertheless possess the dark colour, and transverse markings, which are charac- * Between these extremes in shape may be ranked the ventricles of the camel, horse, ox, giraffe, calf, hare, rabbit, &c. t See photograph of a wax cast of the interior of the ventricles of a deer's heart, Plate XII. figs. 16 & 17, and transverse sections, Plate XV. figs. 49 to 53 inclusive. X The ventricles of the American elk are devoid of carneae columnse, as are likewise those of the red deer (Plate XV. fig. 48).