109 



ation may be represented by a trefoil^ having its 

 stem fixed to the spine. 



The muscular fibres form a border from the 

 edges of the two tendinous side lobes to the lower 

 rim of the chest. They will, of course, stretch the 

 diaphragm, when the ribs turn so as to favor this 

 action, viz., concave surfaces of ribs to the front,, 

 i. e., the outer-bearing. The muscular fibres from 

 the front part of the central lobe going toward the 

 breast bone will complete this stretching, when 

 the heads of the ribs, by turning in a contrary 

 direction, i. e., on their inner-bearing, and sinking 

 back into their sockets shall give a double twist to 

 the ribs. 



So far, the movements of the diaphragm are gov- 

 erned by the secondary section of the anterior loind- 

 ing-line, as to the older bearing, and by the primary 

 section of the j^osterior line as to the inner bearing. 



The primary section of the anterior line simply 

 increases the effect of the secondary ; but the 

 secondary section of the j^osterior line which (§ 25) 

 gives inner bearing to the upper C C of the S S, 

 has its action in stretching the diaphragm, aided by 

 additional muscular fibres. These form two long, 

 thick muscles which, between them, gather to- 

 gether the tendinous fibres from the whole sheet 



