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.

    47/70 page 43
    other. Diagram C 1.2, figs. VI.a.b. § 18. On inspiration, the angles between the ver- tebral and sternal ribs become more open ; the sternum moves forwards and the spinal column slightly backwards, and the chest is slightly expanded. These move- ments are effected by the combined action of the scaleni and sterno-costal muscles on the first vertebral and first sternal ribs respectively; of the levatores costarum and external intercostals on all the lower vertebral ribs ; and of the sternal intercbstals on all the lower sternal ribs. §§ 19. 20. 23. 24. fig. VI. b. diagram C 2. On expiration, the movements are reversed by the internal intercostals, the external and internal oblique, recti, transversales, and other muscles. § 26, fig.VI.a. diagram C1. In the Mammalia (§§ 28-100. Plates XXVI.-XXIX. figs. VII.-XV*.) the addition of a large and efficient diaphragm—that in the Bird is small—modifies the form and varies the movements of the ribs and actions of the muscles in different parts. The ribs articulate with a dorsal arch (§ 31. X. c.) ; they vary in length, those hinging on the centre of the dorsal arch are the longest; while those on the superior curve gra- dually shorten from below upwards ; those on the inferior curve shorten from above downwards. Diagram D 1.2. O. 1.2. figs. XIV. a.b. §§ 31. 32. 33. By virtue of this arrangement, the ribs, articulating with the superior curve, when they are raised, approach each other anteriorly. These ribs have each a cartilage articulating with the sternum, that is analogous to the sternal rib of birds ; they comprise the thoracic set. § 34. 35 Ass, §§ 67 Dog, 79 Man. The ribs that hinge on the inferior curve of the dorsal arch, when raised, recede from each other; they have floating cartilages, and are the diaphragmatic set of ribs. §§ 34. 35. 67. 79. Intermediate are the longest ribs connected with the dorsal arch ; their cartilages are usually linked together and articulate with the lower end of the sternum ; they, when raised, usually recede slightly from each other. Diagram N2, fig. XIII. b. All the ribs recede from each other behind (Diagram M2, fig. XV. b.). The anterior por- tions of the ribs move forwards and upwards, and carry with them the costal carti- lages and the sternum (O. 2. fig. XIV. b). The posterior portions of the ribs move backwards, push backwards the vertebrae, and deepen the dorsal arch. Diagram O, fig. XIV. b. The scaleni invariably act during the whole time of an inspiration (§§ 47. 58. 82); and in Man and the Porpoise they expand the portion of lung in the neck (§§71- 83), assisted in Man by the pleural scalenus (§ 84). They do not draw the cervical ver- tebrae to either side, but they draw them, during inspiration, forwards and downwards (§§ 72. 82). The external intercostals between the thoracic set of ribs are throughout inspiratory (§§ 48. 60. 85); those portions between their cartilages are expiratory (§ 60); between the diaphragmatic set of ribs they are inspiratory behind, expiratory to the side and in * And numerous additional drawings in the Archives of the Royal Society.
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