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, John Frederick Halls, 1877-1944.
Date:
[1908?]
Catalogue details

Licence: In copyright

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.

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.

    5/58 (page 163)
    nS* (a) Inspiratory, (h) Expiratory, (c) Muscles of fixation. 3. Larynx, trachea, bronchi, and lungs. “Mammals alone possess a perfect thorax, i.c. a closed cavity for the heart and lungs, with movable walls and a muscular partition, the diaphragm separating the thoracic from the abdominal cavity ” (’’). III. THE MECHANISM OF RESPIRATION IN MAN. “Accurate representations of the exterior and interior of the dead body give no adequate idea of the movements and varying position of those parts during life ” (Sibson). In order clearly to understand the nature of the events which take place during the different phases of the respiratory cycle it is necessary to broaden one’s outlook and to regard the mechanism of respiration as influencing, and, in turn, being influenced by, the whole structure of the organism. Any variation in the contour of the trunk produced by muscular action, or any change in size of the body-cavity, produces a definite and corresponding effect upon respiration. All the other systems influence to some degree the character of the respiratory movements, especially the nervous system in con- scious or subconscious action. No conception has hindered our progress in respiratory mechanics so much as that which for centuries has figured the body-cavity as divided into two compartments by a “transverse septum ”—the diaphragm. This half-truth is more misleading than the worst falsehood. The clearest idea of the mechanism of respiration is probably gained by regarding man from the comparative standpoint, and his abdominal and thoracic cavities as together constituting one coelom; the diaphragm being considered as a structure sub- sequently introduced within the body-cavity, primarily in order to aid the flow of blood, and secondarily to play its part as a respiratory muscle. On reviewing this aspect of the case we see that the influence of respiration prevails in continuity throughout the body-cavity, 'the whole of the contents being acted upon by the movements of breathing, and the regional effects of these being manifest from neck above to perineum below. The study of the mechanism of respiration is essentially difficult inasmuch as fixation of any given portion of the trunk