Mechanism of reflex nervous action in normal respiration / by Austin Flint, jr. ; [phonographically reported by Geo. W. Wells].

  • Flint, Austin, 1836-1915.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Mechanism of reflex nervous action in normal respiration / by Austin Flint, jr. ; [phonographically reported by Geo. W. Wells]. 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.

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    in 1664, is very instructive. It consisted in introducing a bellows into the trachea of a dog, making an opening into the chest, cutting off a portion of the lungs, and forcing air through them ; and it was found that, so long as air was forced through the lungs in this way, the animal, though sensible, made no efforts at respiration. I may here anticipate enough to say that I shall assume that, in this experiment, while air was sup- plied to the system, the animal felt no want of it, had no in- clination to respire, and consequently did not respire. In studying the subject of the reflex nervous action in res- piration, we are immediately struck with the anatomical rela- tions of the pneumogastric nerves to the respiratory apparatus; and it is all the more important to study the relations of these nerves to the process of respiration, as they arise near that point in the medulla oblongata where the so-called “vital knot,” or the respiratory nervous centre, is supposed to be situated. It might be opportune, perhaps, to rapidly sketch the con- dition of our knowledge respecting the influence of the pneu- mogastric nerve upon respiration. As you all know, the pneumogastric nerve is one of im- mensely wide distribution, and is connected with various dis- tinct functions. The branches that are distributed to the respiratory organs are the following: The superior laryngeals, which are distributed to the mu- cous membrane of the larynx and the membrane covering the top of the larynx, sending off’ a branch on either side to the crico-thyroid muscle, this branch being a mixed nerve. Next in order, we have the inferior, or recurrent laryngeal nerves, which are distributed to all the intrinsic muscles of the larynx, except the crico-thyroid. These nerves are composed entirely of motor fllaments, and are derived from a variety of sources. The experiments of Bernard, which have been so often repeated by Dr. Dalton, myself, and others, of extirpa- ting the spinal accessory nerves, or the section of the com- municating branches to the pneumogastrics, show that this is the nerve of phonation ; and the filaments that preside over the voice pass to the larynx through the recurrent laryngeals. Then we have, distributed to the lungs themselves, the an- terior and posterior pulmonary branches, which go, almost ex-