On the mechanism of respiration / by Francis Sibson, Esq.

  • Francis Sibson
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: On the mechanism of respiration / by Francis Sibson, Esq. Source: Wellcome Collection.

    46/70 page 42
    If any part contiguous to the ribs, on one side, would be injured by the respiratory motion of those ribs, then that side of the chest is often motionless, though the lung be sound. If the air-cells be dilated, the whole chest takes on permanently the form that it has on a deep inspiration. These instances show the practical value of a thorough knowledge of the healthy respiratory movements of each portion of the chest; the attention is at once called to any point that, owing to disease, has not its due motion. The above paper relates almost exclusively to the mode in which the movements of the ribs expand and contract the chest in respiration ; the diaphragm is only treated of incidentally. The remarkable series of respiratory movements that take place in the nostrils, lips, mouth, palate and tongue, in the larynx and pharynx, and in the cervical fasciae, are not even mentioned. On a future occasion I hope to investigate those parts of the mechanism of respi- ration that are here only briefly alluded to, or altogether omitted. SUMMARY. Demonstrative proof of the statements in the following summary is, I believe, ad- vanced in the preceding paper and its accompanying drawings. The Snake (§§ 3-11. Plate XXIII. figs. 1. II.) has the most elementary form of ribs. They are all alike, and are only attached at their vertebral end, their anterior ends being free (§ 4). There are neither sternum nor costal cartilages. When the lungs are expanded, the levatores costarum, and the external intercostals raise the ribs, widen the spaces between them, make their anterior ends move for- wards, and cause the upper edge of one rib to glide backwards in relation to the lower edge of the rib above it. Diagram A 1.2, fig. I. a.b. §§ 4. 6.7- 10. The scalenus acts on the first rib. The levatores costarum draw the ribs backwards behind, outwards to the side. Diagram B 2, § 9. When the lungs are emptied the movements of the ribs are exactly reversed by the long depressors of the ribs, and by the internal intercostals and the transversalis. Diagram A1, B1, §§ 6, 11. In Birds (§§ 17-27- Plate XXIV. XXV. figs. III.-VI.) a sternum and sternal ribs are coupled with the vertebral ribs and vertebrae to complete the circuit of the chest (^17). The respiratory movements, and the muscles exciting the movements of the sternal ribs on the sternum and on each other, are exactly the same in principle, though reversed in direction with those of the vertebral ribs on the vertebrae and on each
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