The diaphragm in man : a record of our present knowledge of its development, relationships, structure and mode of action / by J.F. Halls Dally.

  • Dally, J. F. Halls (John Frederick Halls), 1877-
Date:
[1908?]
Catalogue details

Licence: Public Domain Mark

Credit: The diaphragm in man : a record of our present knowledge of its development, relationships, structure and mode of action / by J.F. Halls Dally. Source: Wellcome Collection.

    11/56 page 171
    relationship of the diaphragm with the pulmonary roots sug- gested an idea, found later to be only partially true, that the diaphragm appeared first, not as a partition, but as muscular bands which acted directly on the roots of the lungs, pulling them during inspiration downwards and forwards. Investi- gation in infants shows that the diaphragm must originate within the layers of mesentery which separate the right from the left half of the ccelom, since the diaphragm lies between the pleuro-peritoneal openings. Probably in the ancestry of the mammalia the whole insertion of the dorsal part of the amphibian diaphragm was transferred to the mesentery of the fore-gut, and, within that structure, reached the pericardium, not on the lateral aspect of the lungs, but on their mesial aspect. Hvidence derived from the nerve-supply predicates two distinct muscular elements in the diaphragm. ‘It is impossible to conceive that the mammalian diaphragm arose from any structure found in extant birds or reptiles,” and, on reviewing the latter-day amphibia, homologues were discovered amongst Anura which functionally correspond with the mam- malian diaphragm in regard to its primary and most important faculty of filling the heart with blood. As exemplified by its primitive arrangement in fishes, the septum transversum 1s correlated in function with the amphibian diaphragm for the same circulatory object, serving, as it does, to separate two cavities in which the conditions of circulation are at variance. Further developmental evidence shows that the origin of the mammalian diaphragm must be sought in that of the tailed amphibia, until finally one reaches the conclusion that the mammalian diaphragm represents the cervical wall or dia- phragm of the amphibian abdominal cavity which is perforated and displaced by the development of the lungs, the point of perforation becoming the pleuro-peritoneal aperture. In 1895, in a paper on the anatomy of the Surinam toad (Pipa Americana), F, E. Beddard (*?) directed attention to a narrow muscular sheet, which, arising close to the rectus femoris, expands fan-wise as it proceeds forwards, and gains insertion into the dorsal aspect of the cesophagus, root of lung, and a fibrous expansion which, investing the liver and con- tinuous with the pericardium, constitutes the cervical aponeu- rosis of the abdominal cavity. This structure Beddard regarded as homologous with the mammalian diaphragm, and compared it with the rudimentary diaphragm of Rana, which he con- sidered to represent the anterior portion of obliquus internus. A special muscle running from ilium to lung and cesophagus corresponding with that found in Pipa was found, too, in the
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