RESPIRATION IN MAN 205 



vex ovoid facet, and fits into a corresponding hollow facet on the 

 transverse process unlike the flat facets of the lower rib. Each 

 transverse process from above downwards is tilted a little more 

 backwards than the one above, so that the angle at which the ribs 

 are set to the spine increases as one passes down the series. The 

 double articulation of each rib to the spine by its head and by its 

 tubercle prevents any rotation of the rib round a sterno-spinal axis. 

 There can be no " bucket-handle " movement. The axis on which 

 the upper ribs move corresponds to their necks. The only part of 

 the erector spinae which can influence their movement is the acces- 

 sorius. The series of slips included in this muscle rises from the 

 lower set and is inserted into the upper set of ribs. It is 

 physically possible for this muscle to act on the upper set during 

 expiration. The muscles named levatores costarum increase in 

 size from first to twelfth, being thus largest to the rib which is in 

 least need of elevation ; they are so inserted to the ribs as to be 

 unable to influence the movements of the ribs ; they are not con- 

 cerned in respiration but in lateral movements of the spine. 



One can see from the shape of the upper ribs that their 

 mechanism is totally different to the lower set. The ribs of the 

 upper set have a concave upper margin, the lower convex ; the 

 upper ribs are shaped like the blade of a sickle ; each successive 

 rib from second to fifth making a greater lateral and forward 

 sweep than the rib above it. The ribs of the lower set form a 

 vertical series, the one situated vertically above the other. The 

 upper set is designed for the expansion of the conical upper lobe, 

 the lower set for the expansion of the lower lobe which is a segment 

 of a cylinder. 



Recently Dally has again directed attention to extension of 

 the spine as a normal means of expanding the thorax. He has 

 studied the spinal movements by means of the othodiascope. 

 Hutchinson and Hasse have each demonstrated a normal in- 

 spiratory extension of the spine. Extension of the spine causes 

 an increase in all three diameters of the thorax. 



It would carry this article to an undue length were the writer 

 to deal fully with other matters connected with the mechanism 

 of respiration, such as its influence on the circulation (eee Wencke- 

 bach and T. Lewis) ; with the changes which set in soon after 

 adult life and gradually increase until old age (see Mehnert). He 

 feels he has scarcely done justice in his review to the articles of 



