389 



high and the clavicular angle should approximate to the adult male 

 type rather than to the adult female. Reference to Column A in the 

 Appendix shows that the reverse is true. The clavicular angle in the 

 child of both sexes is practically the same as that in the adult female 

 (seeFig.IY). I then realised that in the interpretation of the results obtained 

 by measurement of the clavicular angles I had no guarantee that the 

 inner end of the clavicle was a fixed point. As the inner end of 

 the clavicle rests on the thoracic operculum (first rib and manubrium), 

 any variation in position of the anterior end of the first rib relative 

 to the vertebral column will have an effect on the position of the 

 inner end of the clavicle. Thus, should the anterior extremity of the 

 first rib be tilted downwards and the position of the shoulder (outer 

 end of clavicle) be unchanged, the clavicular angle will be increased. 

 If the anterior extremity of the first rib be raised, the shoulder re- 

 maining fixed, the clavicular angle is lessened. 



A very considerable error is thus introduced into the interpre- 

 tation of results recorded in Column A. In order to ascertain the 

 relative mobility of the thoracic operculum (1st ribs and manubrium), 

 I measured the range of movement of the upper border of the manu- 

 brium in quiet and in deep respiration, in adults of both sexes, and 

 in the following positions: — 



(1) Standing 



(2) Sitting 



(3) Stooping 



(4) Lying down. 



The measurements were made on twelve males, of ages varying 

 from 22 to 56, and on twelve females of ages 22 to 63 years. 



The results showed that in quiet respiration the excursion of the 

 upper border of the manubrium is greater in females than in males 

 in quiet respiration, and that in both sexes the respiratory excursion 

 is greater when the patient is lying down than when he or she is 

 standing up. In the sitting and stooping positions the respiratory 

 excursion of the operculum is greater than in the erect position, but less 

 than in the horizontal position. The patients were dressed simply 

 in blankets and thus the effect of corsets or other clothing was 

 eliminated. When the patient is standing up the tonic action of the 

 recti abdominis anchor the sternum and so diminish the respiratory 

 movement of the operculum. In women who have been accustomed 



