RESPIRATORY MOVEMENTS. 207 



the antero-posterior diameter of the chest, by partially 

 straightening out the angle between the rib and its carti- 

 lage, and thus lengthening the distance between its spinal 

 and sternal attachments (fig. 62, A). In this way, at the 

 same time that the ribs are raised, the sternum is pushed 

 forward. The differences in shape of the upper and lower 

 Fig. 62. 



true ribs, and the more acute angles formed by the junction 

 of the latter with their cartilages, make the effect much 

 greater at the lower than at the upper part of the chest. 



The expansion of the chest in inspiration presents some 

 peculiarities in different persons and circumstances. In 

 young children, it is effected almost entirely by the dia- 

 phragm, which being highly arched in expiration, becomes 

 flatter as it contracts, and, descending, presses on the 

 abdominal viscera, and pushes forward the front walls of 

 the abdomen. The movement of the abdominal walls 

 being here more manifest than that of any other part, it is 

 usual to call this the abdominal mode or type of respiration. 

 In adult men, together with the descent of the diaphragm, 

 and the pushing forward of the front wall of the abdomen, 

 the lower part of the chest and the sternum are subject to 

 a wide movement in inspiration. In women, the move- 



