DIAPHRAGM AND ITS ACTION. 



485 



fibres are directed inwards, with different degrees of obliquity and length, 

 to the central tendon, but some have a peculiar disposition in the pillars 

 which will be afterwards noted. 



The abdominal surface is concave, and is covered for the most part by 

 the peritoneum. In contact with it on the right side are the liver and the 

 kidney ; and on the opposite side, the stomach, the spleen, and the left 

 kidney: in contact also with the pillars is the pancreas, together with the 

 solar plexus and the semilunar ganglia. The thoracic surface is covered 

 by the pleura of each side and the pericardium, and is convex towards the 

 thorax (p. 343). At the circumference of the midritf the fleshy processes 

 of origin alternate with like parts of the transversalis muscle; but a slight 

 interval separates the slips to the xiphoid cartilage and seventh rib, and a 

 second space exists sometimes between the fibres from the last rib and the 

 arch over the quadratus lumborum muscle. In it are certain apertures for 

 the transmission of parts from the thorax to the abdomen. 



The muscle is convex towards the chest, and concave to the abdomen. 

 Its arch reaches higher on the right than the left side (p. 306), and is con- 



Fte. 170. 



UNDER SURFACE OF THE DIAPHRAGM. 



A. Diaphragm. d. Left, and e, right cms. 



B. Psoas magnus. /. Inner, and g, outer arched ligament. 



c. Quadratus lurnborum. h. Opening for vena cava ; i, for (Esophagus, t, 



a. Left piece of the tendon of the diaphragm ; for aorta, j, for sympathetic nerves. 



6, middle; and c, right piece. 



stantly varying during life in respiration. In forced expiration the muscle 

 ascends, and reaches as high as the upper border of the right fourth rib at 

 the sternum, and the upper edge of the fifth rib on the left side, close to 

 the sternum. In forced inspiration it descends, and its slope would be 

 represented by a line drawn from the middle of the ensiform cartilage to 

 the eleventh rib. 



Action. As the muscle moves up and down during respiration, it is 

 depressed by the contraction of the fleshy fibres which are attached to the 

 ribs and spine, and is raised during their relaxation. 



