On the mechanism of respiration / by Francis Sibson.

Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: On the mechanism of respiration / by Francis Sibson. 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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    CI. C 2. While the ohliquity of the vertebral ribs is from behind forwards and downwards, that of the sternal ribs is from before backwards and downwards. The motions of the sternal ribs on the sternujn are precisely the same in principle with the motions of the vertebral ribs on the vertebrae, only they are all reversed. While the distant ends of the latter ribs when raised move forwards from the vertebrae, those of the former move backwards from the sternum ; while the upper edge of each vertebral rib glides backwards in relation to the lower edge of the rib above (§ 6, 7), that of the sternal rib glides forwards. The same holds as to the muscles; while the scalenus or levator costae (1) raises the vertebral rib, the sterno-costalis (3) elevates the first sternal rib; while the ex- ternal intercostals (2) elevate and give the gliding motion to the vertebral ribs (§ 6, 7), the sternal intercostals (4) give the same motions to the sternal ribs ; and while the muscles of the vertebral ribs are directed forwards and downwards, those of the sternal ribs pass backwards and downwards. The two sets of muscles combine in one action to raise the ends by which the two sets of ribs articulate with each other 6, / )• 19. On inspiration, the angles formed by the ribs are more open, the sternum and spinal column more distant. In diagram C 2, inspiration, the angle d.c formed by the articulation of the two ribs is much n»ore open than in diagrani C 1, expiration; in the latter they are bent to a right angle, in the former they are nearly straight. As the costal ends of the ribs are more distant from the sternum and vertebrae in inspiration C 2 than in expiration C ], so, to a double extent, is the distance increased between the sternum and the spinal column ; if the spinal colunm be fixed, the sternum moves forwards to a very great extent.