384 



ABDOMEN 



R.P. 



it descends behind the peritoneum, from which it is partial!] 

 separated by the right internal spermatic or ovarian vessels, 

 the right colic and the ileo-colic vessels, and the terminal parts 

 of the superior mesenteric artery and vein. The whole of 

 the abdominal portion of the left ureter is in relation, in 

 front, with the peritoneum, except that it is crossed anteriorly, 

 behind the peritoneum, by the left internal spermatic or 

 ovarian vessels, the left colic vessels, and the sigmoid vessels. 



Dissection. Having now studied all the viscera within the 

 cavity of the abdomen proper, the student should, in the next 

 place, direct his attention to the dia- 

 phragm the great muscle which con- 

 stitutes a movable partition between the 

 thoracic and abdominal cavities. Strip 

 the peritoneum from its lower, concave 

 surface ; clean the muscular fibres and 

 the central tendinous expansion towards 

 which they ascend, but be careful to 

 preserve the inferior phrenic arteries, 

 which ramify upon the inferior aspect 

 of the diaphragm, and also the nerves 

 which accompany them. 



Diaphragma. The diaphragm, after 

 the heart, is the rriost important muscle 

 in the body. It forms the dome-shaped 

 roof of the abdomen, and the highly 

 arched and convex floor of the thorax. 

 It is the chief muscle of respiration. 

 Each respiratory act is accompanied by 

 c. Cut edgeTf a calyx ^ ts descent and ascent, and in that way 

 >f the pelvis of the ureter. the capacity of the thoracic cavity is 

 alternately increased and decreased in 



the vertical direction. The vault or cupola of the diaphragm 

 is higher on the right side than on the left side of the body. 

 In forced expiration it may rise, on the right side, as high as 

 the upper margin of the fourth rib, in the right lateral line ; 

 whereas, on the left side, it reaches only as high a.s the upper 

 border of the fifth rib (Fig. 36). 



The central portion of the diaphragm is tendinous. From 

 the tendon the fleshy fibres radiate, and at the same time 

 arch downwards, to obtain attachment to the circumference 

 of the lower aperture or outlet of the thorax. Anteriorly, 

 the diaphragm takes origin from the posterior surface of the 

 xiphoid process ; laterally, it arises from the lower six costal 



FIG. 182. Diagram of 

 two Renal Papillae. 



R.P. Renal papilla. 



