Report on the progress of human anatomy and physiology in the year 1842-3 / [Sir James Paget].

  • James Paget
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1842-3 / [Sir James Paget]. Source: Wellcome Collection.

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    the intercostal spaces may be reduced to considerably less than it is in ordinary expiration. MM. Beau and Maissiat investigated also at great length the actions of the respiratory muscles, both by feeling and looking at them while in action, and by vivisections of dogs. Their conclusions, so far as the muscles are concerned in respiration, are briefly as follows, and many of them may be confirmed by observa¬ tion on one’s own person. Intercostals : In inspiration, they are elongated, and become hard and concave on their outer surface ; in quiet expiration, they are mode¬ rately shortened, and become less hard and flat; in complex and forcible expira¬ tion, they become prominent and very short and hard. They are therefore muscles for forcible expiration, like their analogues, the oblique muscles of the abdomen ; their hardness in inspiration is due to their being stretched; but their contraction (except by their elasticity) is only seen in forced expirations or in efforts. [For many reasons, this conclusion must be considered very doubtful. The experi¬ ment on which the authors chiefly found their belief that the intercostals cannot raise the ribs, consisted in cutting through the pectoral muscles and the whole length of the intercostals between the sixth and seventh ribs on both sides: after this was done the lower ribs were still raised in inspiration (as they suppose) by the diaphragm. Perhaps no conclusion ought to be drawn from the results of such mutilation; but M. Debrou (Gazette Medicale, Jan. 3, 1843,) having re¬ peated the experiment, with the addition of cutting the diaphragm from the ribs, and having found that the ribs were still raised in inspiration, maintains that the five lower ribs are thus raised by their intercostal muscles, and that the sixth, from which the intercostals above were cut away, is pushed up by the fifth. The fol¬ lowing arguments appear to me conclusive in favour of the usually inspiratory action of the intercostals. 1. When the spinal cord is injured below the origins of the phrenic nerves and above those of the intercostal nerves, the ribs are very nearly motionless in respiration, for the intercostal muscles are paralysed though the diaphragm is active. 2. The upper ribs are chiefly moved in the superior costal respiration, though the diaphragm cannot act upon them. 3. The levatores costarum, which can act in inspiration alone, have an arrange¬ ment exactly analogous to that of the external intercostal muscles. 4. Whenever the intercostal muscles are affected by diseases in which the pain is increased by muscular contraction, there is an increase of pain in inspiration.] The authors believe also (and with more probability, for whatever be their ordinary action, the intercostals may in extraordinary circumstances, act in either direction,) that, in forcible expiration they serve to make the whole walls of the chest rigid and resisting, so that they may not be distended by the eccentric impulse of the lungs, which are compressed on every side, and especially by the diaphragm. Levatores costarum : supposed (but improba¬ bly) to be not concerned in respiration, but to serve for maintaining the spine erect. Infra costales : probably muscles for forcible expiration, like the internal intercostals. (?) Triangularis sterni: a muscle of expiration, by drawing together the sternum and the costal cartilages. Scaleni: muscles of inspiration, especially in the superior costal type of movements, but chiefly flexors of the head. Sterno- mastoid: auxiliary to the scaleni in forcible inspiration. Trapezius: its upper border assists in forcible inspiration, its longer border in forcible expiration. Leva¬ tor anguli scapul-x : acts with the upper part of the trapezius in violent inspiration. Subclavius, depressor of the clavicle after forcible inspiration. (?) Latissimus dorsi: its lower border acts in forcible expiration, as one may find by feeling the posterior wall of the axilla while coughing; at the same time it makes rigid those parts of the walls of the chest and abdomen on which it lies, and it presses in the lower ribs. Serratus magnus: acts in forcible inspiration, but chiefly (as was shown in a patient in whom it alone was paralysed,) it serves, by cooperating with the deltoid, in raising the arm. Serratus posticus superior: not a respira¬ tory muscle, (?) but an extensor of the neck. Serratus posticus inferior: expi¬ ratory. Pectoralis major : its lower quarter is a muscle of inspiration, its upper three fourths form one of expiration, but it does not act except in dyspnoea. Pectoralis minor: its lower half acts habitually (?) as a muscle of inspiration.