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ON THE MODE OF ACTION OF THE PNEUMOGASTRIC NERVE.
15 ON THE
these muscles has not been hitherto, I he-’ lieve, satisfactorily explained. Some ana-
tomists have argued against their existence from their utter uselessness, and others OF THE have merely admitted them to explain some of the phenomena of disease. The followPNEUMOGASTRIC NERVE. ing appears to me the proper explanation of By JAMES CARSON, Jun., M.B.T.C.D., the part which they perform in the mechanism of respiration. Liverpool. The cavity of the lungs into which the A MEMOIR having the above title was air enters may be divided into two parts. published by MM. Breschet and Edwards, If the boundaries of these be not pointed in the 7th volume of the A)-chives Générales out by their anatomical characters, a phvde Médecine. In their paper these physio- siological distinction must be admitted belogists confined themselves to the investi- tween the tubes conveying’ the air and the gation of the influence of the pneumogastric cells in which the changes take place in nerve on the function of digestion. By a that fluid. Around the tubes alone I should series of well-arranged experiments, they suppose the muscular fibres to exist. It is were enabled to reconcile the discrepant to them that the pneumogastric nerves are effects observed, on one side, by Blainville, distributed. Philip, and Hastings, and on the other by I In inspiration these muscles, in concert Magendie, of the section of this nerve. In with the other respiratory muscles, contract. admitting the restoration of the injured They produce the effect of diminishing’ the function when a stream of galvanism was di- cavities of the tubes, while the diaphragm, rected through the nerves, they at the same intercostals, and other inspiratory muscles, time showed that the same restoration was increase the general capacity of the lungs. effected by its mechanical irritation. And The result of these combined motions is a in deprivingthe nerve of its supposed che- dilatation of the cells, and thus a greater mical influence in digestion, they have surface of their lining membrane by which proved that it aids that function, merely the air is changed is exposed to a greater by influencing the muscular motion of the quantity of air. The dilatation produced stomach by which the food is brought in in the cells by this mechanism is greater contact by renewed surfaces, with the digest- than that which would be produced on the ing surfaces of that viscus. Analogy would supposition that the tubes were inert, by lead us to suppose that the function of this the quantity by which the muscles diminerve as it is distributed to the lung was nish the tubes, together with the quantity equally simple. That it is not a chemical by which the latter would have been ininfluence which is exerted by it in the creased in the general dilatation of the which take place in the blood and lungs. If we consider the great proportion the air, may be argued from the fact, that which these tubes form of the capacity of the fibrils of this nerve are distributed over the lungs, the effect produced cannot be inthe whole of the bronchial tubes, whereas considerable. Whatever be the view of these changes are admitted to be effected the mode bv which the changes are induced in the cells or the more minute tubes alone. in the blood by the air, the condition of In the following paper a part of the me- I parts in this way produced is undoubtedly chanism of respiration will be pointed out, the most favourable for effecting them. I believe not hitherto noticed, over which The mixture, moreover, of the fresh with this nerve presides, and whose derange- the polluted air is more thoroughly effected If the ments are sufficient to account for the se- by the mechanism in question. above theory be correct, I think it is not rious results of its section or lesion. In the splendid work which Russessen difficult to explain the function of the pneuhas published on the minute anatomy of the mogastric nerve in the lungs. Distributed lungs, he has depicted a series of muscular to the muscular fibres of the bronchia: fibres investing the bronchial tubes. These through their contraction, it renews the he has represented as not only existing in air, and increases the surfaces of the cells the larger tubes, but also extendingto the by which it is exposed to the blood, permore minute bronchiæ. In the mammalia, forming an analogous function in respiraan evident provision is made for their con- tion to that which MM. Breschet and Edtraction, in the deficiency which exists in wards have shown to be performed by it in the posterior parts of the cartilaginous digestion. The lesions of this nerve will rings of the larger bronchio3. I shall as- be attended with consequences proportioned sume their existence in the smaller tubes, to the importance of the functions over depending on the authority of Russessen, which it presides. Dr. Philip was so struck and on one or two phenomena only explicthe resemblance of the effects of its able on this supposition. The function of" section to asthma, that he did not hesitate
MODE OF ACTION
changes
with
12
ing the violent efforts which the animal to attribute the spasmodic and asthma to a neurosis of this nerve. And makes to inspire, are dilated. if we consider that a constant attendant on This he has explained by supposing an these diseases is a severe fit of dyspepsia, active expansive power in the cells themwe may recognise the lesion of the nerve selves. As I am not aware of any analogous in that of both the functions over which it process in the animal economy, I have less presides. These diseases I should suppose hesitation in suggesting, as a better explato depend on paralysis of the muscular ap-nation, the following:—During inspiration, paratus which L have above explained ; and i all those muscles which are associated in their difference, which is merelv one of this act still contract. Among these are muscles investing the bronchial tubes. degree, depends on the greater or less extent of that paralysis. Cullen has attributed By their contraction a portion of the conthe phenomena of spasmodic asthma to a tents of the tubes, greater in proportion to spasm of the bronchia, to which explana- the violence of the inspiration, will be into the cells, and the dilatation tion .Laennec has acceded, pointing out these muscles :’.s its seat. In favour of this which takes place in these gives the appearof a general dilatation in the whole opinion Dr. Forbes, in his paper on Asthma, published in tlie " Cyclopædia of Medicine," has cited the stethoscopic phenomena. In March, 1832. the paroxysms of this disease the respiratory murmur is not distinguishable. This total absence of sound must depend, on the THE supposition of spasm, on a complete occlusiou of’ the tubes in which the sound is PRELIMINARY DIARRHŒA AND formed, otherwise the diminution of these CONSECUTIVE FEVER alone would be attended with much inOF THE creased sound. But it is well ’known that the sufferers in this disease are MALIGNANT CHOLERA; of the entrance of the air into the lung, and FEATURES ALIKE, OF THAT DISEASE, IN therefore the diminution of the tubes could INDIA AND ENGLAND. not be complete. But suppose the disease to depend on paralysis of these muscles, then the air, instead of passing’ through To the Editor of THE LANCET. diminished tubes, enters into a comparatively free space formed by the dilated SIR,—Observing with surprise, by your tubes, and the resistance to its passage isvreport of the proceedings of the Westminso small as not to excite the least sound. ster Medical Society on Saturday evening the The dyspnoea, arises from the incomplete 10th instant, that an attempt was then made development of the surfaces of the cells, as by a gentleman of so justly-esteemed literary explained in the former part of this paper. reputation as Dr. James Johnson, to foster There are two phenomena which I shall the unaccountable delusion, of late verv cite as proofs of the muscularity of the entertained, that consecutive fever bronchiæ being-, I believe, only explicable , is unnoticed in the published accounts of the on that supposition; viz. puerile respiration(epidemic cholera of india, vou may perhaps and theactive dilatation of the lungs ob-deem it worth while to point the attention of your readers to the following extract from served bv Laennec. Puerile respiration is known to take place the Report of the Bengal Medical Board, when a lung, or part of a lung, is renderedpublished at Calcutta so long since as the I 1819. iml.ervious to air. In the sound lung the vear After giving a minute history of the manrespiratory murmur increases to such a gree as to resemble the sound of breathing ner of attack and general symptoms, the in infants. This lung is said to take on a Report enters into Mi elaborate detail of the compensating action. The proper explana- varieties that the symptoms would occation oiit is this : in order that a larger sur- sionally present, and then gives the followface of the cells of the sound lung’ may be ing luminous description of what ensued exposed to the ntr.:ospLeric influence, the when the system succeeded in rallying tubes are proportionably diminished. It is from the rude shock it had received." to the increased resistance wi ich they op" When the disorder ran its full course, pose to the passage of the air that the sound the following appearances presented themis to be attributed. selves :—What may be termed the cold Laennec has observed, that if the parietes stage, or the state of collapse, usually of the chest be removed in a living animal, lasted from 24 to 48 hours, and was seldom although by this means the mechanism by of more than three complete days’ duration, which inspiration is generally supposed to Throughout the first twenty-four hoars,
continued)
I ’IB
the
thrown I. IB ance lung.
IB
conscious
IBgenerally
de- I
"
’
be
performed be destroyed, the lungs, dur- nearly all the symptoms ofdeadly opprw
these muscles has not been hitherto, I he-’ lieve, satisfactorily explained. Some ana-
tomists have argued against their existence from their utter uselessness, and others OF THE have merely admitted them to explain some of the phenomena of disease. The followPNEUMOGASTRIC NERVE. ing appears to me the proper explanation of By JAMES CARSON, Jun., M.B.T.C.D., the part which they perform in the mechanism of respiration. Liverpool. The cavity of the lungs into which the A MEMOIR having the above title was air enters may be divided into two parts. published by MM. Breschet and Edwards, If the boundaries of these be not pointed in the 7th volume of the A)-chives Générales out by their anatomical characters, a phvde Médecine. In their paper these physio- siological distinction must be admitted belogists confined themselves to the investi- tween the tubes conveying’ the air and the gation of the influence of the pneumogastric cells in which the changes take place in nerve on the function of digestion. By a that fluid. Around the tubes alone I should series of well-arranged experiments, they suppose the muscular fibres to exist. It is were enabled to reconcile the discrepant to them that the pneumogastric nerves are effects observed, on one side, by Blainville, distributed. Philip, and Hastings, and on the other by I In inspiration these muscles, in concert Magendie, of the section of this nerve. In with the other respiratory muscles, contract. admitting the restoration of the injured They produce the effect of diminishing’ the function when a stream of galvanism was di- cavities of the tubes, while the diaphragm, rected through the nerves, they at the same intercostals, and other inspiratory muscles, time showed that the same restoration was increase the general capacity of the lungs. effected by its mechanical irritation. And The result of these combined motions is a in deprivingthe nerve of its supposed che- dilatation of the cells, and thus a greater mical influence in digestion, they have surface of their lining membrane by which proved that it aids that function, merely the air is changed is exposed to a greater by influencing the muscular motion of the quantity of air. The dilatation produced stomach by which the food is brought in in the cells by this mechanism is greater contact by renewed surfaces, with the digest- than that which would be produced on the ing surfaces of that viscus. Analogy would supposition that the tubes were inert, by lead us to suppose that the function of this the quantity by which the muscles diminerve as it is distributed to the lung was nish the tubes, together with the quantity equally simple. That it is not a chemical by which the latter would have been ininfluence which is exerted by it in the creased in the general dilatation of the which take place in the blood and lungs. If we consider the great proportion the air, may be argued from the fact, that which these tubes form of the capacity of the fibrils of this nerve are distributed over the lungs, the effect produced cannot be inthe whole of the bronchial tubes, whereas considerable. Whatever be the view of these changes are admitted to be effected the mode bv which the changes are induced in the cells or the more minute tubes alone. in the blood by the air, the condition of In the following paper a part of the me- I parts in this way produced is undoubtedly chanism of respiration will be pointed out, the most favourable for effecting them. I believe not hitherto noticed, over which The mixture, moreover, of the fresh with this nerve presides, and whose derange- the polluted air is more thoroughly effected If the ments are sufficient to account for the se- by the mechanism in question. above theory be correct, I think it is not rious results of its section or lesion. In the splendid work which Russessen difficult to explain the function of the pneuhas published on the minute anatomy of the mogastric nerve in the lungs. Distributed lungs, he has depicted a series of muscular to the muscular fibres of the bronchia: fibres investing the bronchial tubes. These through their contraction, it renews the he has represented as not only existing in air, and increases the surfaces of the cells the larger tubes, but also extendingto the by which it is exposed to the blood, permore minute bronchiæ. In the mammalia, forming an analogous function in respiraan evident provision is made for their con- tion to that which MM. Breschet and Edtraction, in the deficiency which exists in wards have shown to be performed by it in the posterior parts of the cartilaginous digestion. The lesions of this nerve will rings of the larger bronchio3. I shall as- be attended with consequences proportioned sume their existence in the smaller tubes, to the importance of the functions over depending on the authority of Russessen, which it presides. Dr. Philip was so struck and on one or two phenomena only explicthe resemblance of the effects of its able on this supposition. The function of" section to asthma, that he did not hesitate
MODE OF ACTION
changes
with
12
ing the violent efforts which the animal to attribute the spasmodic and asthma to a neurosis of this nerve. And makes to inspire, are dilated. if we consider that a constant attendant on This he has explained by supposing an these diseases is a severe fit of dyspepsia, active expansive power in the cells themwe may recognise the lesion of the nerve selves. As I am not aware of any analogous in that of both the functions over which it process in the animal economy, I have less presides. These diseases I should suppose hesitation in suggesting, as a better explato depend on paralysis of the muscular ap-nation, the following:—During inspiration, paratus which L have above explained ; and i all those muscles which are associated in their difference, which is merelv one of this act still contract. Among these are muscles investing the bronchial tubes. degree, depends on the greater or less extent of that paralysis. Cullen has attributed By their contraction a portion of the conthe phenomena of spasmodic asthma to a tents of the tubes, greater in proportion to spasm of the bronchia, to which explana- the violence of the inspiration, will be into the cells, and the dilatation tion .Laennec has acceded, pointing out these muscles :’.s its seat. In favour of this which takes place in these gives the appearof a general dilatation in the whole opinion Dr. Forbes, in his paper on Asthma, published in tlie " Cyclopædia of Medicine," has cited the stethoscopic phenomena. In March, 1832. the paroxysms of this disease the respiratory murmur is not distinguishable. This total absence of sound must depend, on the THE supposition of spasm, on a complete occlusiou of’ the tubes in which the sound is PRELIMINARY DIARRHŒA AND formed, otherwise the diminution of these CONSECUTIVE FEVER alone would be attended with much inOF THE creased sound. But it is well ’known that the sufferers in this disease are MALIGNANT CHOLERA; of the entrance of the air into the lung, and FEATURES ALIKE, OF THAT DISEASE, IN therefore the diminution of the tubes could INDIA AND ENGLAND. not be complete. But suppose the disease to depend on paralysis of these muscles, then the air, instead of passing’ through To the Editor of THE LANCET. diminished tubes, enters into a comparatively free space formed by the dilated SIR,—Observing with surprise, by your tubes, and the resistance to its passage isvreport of the proceedings of the Westminso small as not to excite the least sound. ster Medical Society on Saturday evening the The dyspnoea, arises from the incomplete 10th instant, that an attempt was then made development of the surfaces of the cells, as by a gentleman of so justly-esteemed literary explained in the former part of this paper. reputation as Dr. James Johnson, to foster There are two phenomena which I shall the unaccountable delusion, of late verv cite as proofs of the muscularity of the entertained, that consecutive fever bronchiæ being-, I believe, only explicable , is unnoticed in the published accounts of the on that supposition; viz. puerile respiration(epidemic cholera of india, vou may perhaps and theactive dilatation of the lungs ob-deem it worth while to point the attention of your readers to the following extract from served bv Laennec. Puerile respiration is known to take place the Report of the Bengal Medical Board, when a lung, or part of a lung, is renderedpublished at Calcutta so long since as the I 1819. iml.ervious to air. In the sound lung the vear After giving a minute history of the manrespiratory murmur increases to such a gree as to resemble the sound of breathing ner of attack and general symptoms, the in infants. This lung is said to take on a Report enters into Mi elaborate detail of the compensating action. The proper explana- varieties that the symptoms would occation oiit is this : in order that a larger sur- sionally present, and then gives the followface of the cells of the sound lung’ may be ing luminous description of what ensued exposed to the ntr.:ospLeric influence, the when the system succeeded in rallying tubes are proportionably diminished. It is from the rude shock it had received." to the increased resistance wi ich they op" When the disorder ran its full course, pose to the passage of the air that the sound the following appearances presented themis to be attributed. selves :—What may be termed the cold Laennec has observed, that if the parietes stage, or the state of collapse, usually of the chest be removed in a living animal, lasted from 24 to 48 hours, and was seldom although by this means the mechanism by of more than three complete days’ duration, which inspiration is generally supposed to Throughout the first twenty-four hoars,
continued)
I ’IB
the
thrown I. IB ance lung.
IB
conscious
IBgenerally
de- I
"
’
be
performed be destroyed, the lungs, dur- nearly all the symptoms ofdeadly opprw