1872.] 



of the Respiratory Movements in Man. 



13 



Forward. Upward. 



Calculated motion of the end of the 3rd rib 61 160 



Calculated motion of the end of the 5th rib 53 140 



Motion of the Ribs as observed with Stethometer. 



A, when the whole back was supported 



B, when the 3rd and 5th vertebra alone 



were supported 



Extent of forward push of 3rd rib not s 

 Extent of forward push of 5th rib not a 



4. The excess of forward motion is found not to be explained (a) 

 by the genoic-leyeY action of the costal cartilages with the ribs, (b) by the 

 curvature of the spine, (c) by the backward thrust of the angles of the 

 ribs. 



5. It maybe concluded, therefore, that the mechanical conditions of the 

 thoracic machinery would prevent any forward motion to the extent 

 observed, unless it was possible for the ribs themselves either to be inbent 

 or straightened out. 



6. It may be proved that the ribs are capable of being bent (a) by 

 experiments upon freshly separated ribs, (b) upon dead subjects, (c) upon 

 living subjects, (d) by pathological facts. 



7. The means by which an alteration in the chord-lengths of the ribs 

 could be brought about may be discovered in several directions, especially 

 in the intrinsic thoracic muscles. 



8. It may be shown that the hypothesis of either the straightening 

 of the ribs in inspiration, or their previous inbending in expiration, (a) 

 accounts for the extent of the forward indications of the stethometer, (b) 

 their varying amount in the same individual in relation to the upward 

 motion, (c) for the extraordinary extent of these forward indications in 

 women and young children as compared with those of strong men and 

 old people ; (d) it explains the comparatively large extent of forward 

 movement of the upper as compared with the lower ribs ; (e) it is sup- 

 ported by the peculiar stethometric measurements obtained in various 

 Vliseases of the lungs ; (/) by the fact that the excess of forward move- 

 ment is found to increase from the middle to the anterior end of the 

 rib. 



On the Respiratory Motive Powers. — By what means may the inbending 

 or straightening of the ribs be accomplished ? 



That the forces concerned in respiration are sufficiently powerful is 

 proved by several considerations, notably by Hutchinson and Haughton's 

 calculations of muscular power. 



The purely mechanical forces are probably not often brought into 

 action. The effect of the extraordinary or external muscles of respira- 



j 3rd rib . . 135 160 



I 5th rib . . 115 120 



f 3rd rib . . 135 160 



1 5th rib . . 115 120 



ccounted for 0*74 in. 



ccounted for 0*62 



