287 



ABDOMEN AND PELVIS. 



CHAPTER XVI. 



THE ABDOMEN. 



THE abdominal parietes. Surface anatomy. 

 The degree of prominence of the abdomen varies 

 greatly. The protuberance of the belly in young 

 children is mainly due to the relatively large size of 

 the liver, which occupies a considerable part of 

 the cavity in early life. It also depends upon the 

 small size- of the pelvis, which is not only unable to 

 accommodate any abdominal structure (strictly so- 

 called), but can scarcely provide room for the pelvic 

 organs themselves. Thus in infancy the bladder and 

 a great part of the rectum are virtually abdominal 

 viscera. After long-continued distension, as, for ex- 

 ample, after pregnancy, ascites, etc., the abdomen 

 usually remains unduly prominent and pendulous. 



In examples of prolapse of the mesentery the 

 upper part of the abdomen becomes sunken in and the 

 lower part unduly prominent. (See page 326.) 



In cases of great emaciation it becomes much sunken, 

 and its anterior wall appears to have collapsed. This 

 change is most conspicuous about the upper part of the 

 region. Here the anterior parietes immediately below 

 the line of the costal cartilages, instead of being in the 

 same plane with the anterior thoracic wall, may so sink 

 in as to be almost at right angles with that wall on the 

 one hand, and with the lower part of the abdominal 

 parietes on the other. In such cases the abdominal 

 walls just below the thoracic line may appear to be 

 almost vertical when the patient is in the recumbent 



