Observations on certain parts of the animal oeconomy : inclusive of several papers from the Philosophical transactions, etc. / by John Hunter ... ; with notes by Richard Owen.
- John Hunter
- Date:
- 1840
Licence: Public Domain Mark
Credit: Observations on certain parts of the animal oeconomy : inclusive of several papers from the Philosophical transactions, etc. / by John Hunter ... ; with notes by Richard Owen. Source: Wellcome Collection.
Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)
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![muscles of respiration are the active part in emptying the lungs, and can act both naturally and preternaturally. The muscles of the thorax and abdomen do not act naturally on the contents of the abdomen, but often act preternaturally, producing an evacua- tion from its viscera. There is this difference in the action of the parts in coughing and vomiting: the cough is performed by the proper muscles of respiration, which are those of expansion, supported by the abdo- minal, while the diaphragm is passive. Vomiting is performed by the abdominal muscles and diaphragm, while those of inspiration are supporting this action. In coughing the ribs are suddenly depressed, which diminishes the capacity of the thorax; and that the diaphragm may not be allowed to sink down and increase the capacity of the thorax, which would counteract the depressors of the ribs, the abdominal muscles at the same time act, which supports the diaphragm in its place, and probably may by this action assist in bringing down the ribs. To give as much force to this action as possible, the glottis is shut till the action is begun, and then the glottis open instan- taneously, which obliges the depressors of the ribs to begin the effort with their full action. The proper muscles of inspiration do not tire so soon in this action as the abdominal, for in violent coughing the muscles of the abdomen become sore. In vomiting these actions are reversed. The muscles of the cavity of the abdomen act, in which is to be included the diaphragm; so that the capacity of the abdomen is lessened, and the action of the diaphragm rather raises the ribs; and there is also an attempt to raise them by their proper muscles, to make a kind of vacuum in the thorax, that the oesophagus may be rather opened than shut, while the glottis is shut so as to let no air enter the lungs. The muscles of the throat and fauces act to dilate the fauces, which is easily felt by the hand, making there a vacuum, or what is com- monly called a suction ; so that when all these actions take place together, the stomach is immediately emptied. In violent coughing we find that a kind of mixed action takes place; for although the diaphragm has not acted, yet the stomach is so much squeezed as to discharge its contents; and it affects the diaphragm, which is often thrown into action, and brings on vomit- ing at the same time; therefore violent coughing palls the stomach. There is reason to believe that the natural motion in all stomachs vulsive de l'estomac, &c; and then goes on to detail his notorious experiment on the dog, for whose stomach he substituted a pig's bladder; by which he proved, that when rilled with fluid and put into a situation to be pressed upon, the contents of the bladder would flow out. By dividing the phrenic nerves, and paralysing the diaphragm, Majendie also proved that°the abdominal muscles alone were capable of producing vomiting ; and by another experiment, he satis- fied himself that the diaphragm alone was sufficient for that act when all the abdominal muscles had been dissected off, and the peritoneum left entire.]](https://iiif.wellcomecollection.org/image/b21131545_0088.jp2/full/800%2C/0/default.jpg)
